Merge pull request #3398 from babel/revert-rm-flow

Revert "Remove flow"

packages/babel-cli/src/babel-doctor/index.js

@@ -36,7 +36,7 @@ while (nodeModulesDirectories.length) {
   let loc = nodeModulesDirectories.shift();
   if (!fs.existsSync(loc)) continue;
 
-  let packagesNames = fs.readdirSync(loc);
+  let packagesNames: Array<string> = fs.readdirSync(loc);
 
   for (let packageName of packagesNames) {
     if (packageName[0] === ".") continue;

packages/babel-code-frame/src/index.js

@@ -61,7 +61,7 @@ function getTokenType(match) {
  * Highlight `text`.
  */
 
-function highlight(text) {
+function highlight(text: string) {
   return text.replace(jsTokens, function (...args) {
     let type = getTokenType(args);
     let colorize = defs[type];
@@ -77,7 +77,12 @@ function highlight(text) {
  * Create a code frame, adding line numbers, code highlighting, and pointing to a given position.
  */
 
-export default function (rawLines, lineNumber, colNumber, opts = {}) {
+export default function (
+  rawLines: string,
+  lineNumber: number,
+  colNumber: number,
+  opts: Object = {},
+): string {
   colNumber = Math.max(colNumber, 0);
 
   let highlighted = opts.highlightCode && chalk.supportsColor;

packages/babel-core/src/api/browser.js

@@ -4,11 +4,11 @@
 import { transform } from "./node";
 export * from "./node";
 
-export function run(code, opts = {}) {
+export function run(code: string, opts: Object = {}): any {
   return new Function(transform(code, opts).code)();
 }
 
-export function load(url, callback, opts = {}, hold) {
+export function load(url: string, callback: Function, opts: Object = {}, hold?: boolean) {
   opts.filename = opts.filename || url;
 
   let xhr = global.ActiveXObject ? new global.ActiveXObject("Microsoft.XMLHTTP") : new global.XMLHttpRequest();
@@ -32,7 +32,7 @@ export function load(url, callback, opts = {}, hold) {
 }
 
 function runScripts() {
-  let scripts = [];
+  let scripts: Array<Array<any> | Object> = [];
   let types   = ["text/ecmascript-6", "text/6to5", "text/babel", "module"];
   let index   = 0;
 
@@ -53,7 +53,7 @@ function runScripts() {
    * Load, transform, and execute all scripts.
    */
 
-  function run(script, i) {
+  function run(script: Object, i: number) {
     let opts = {};
 
     if (script.src) {

packages/babel-core/src/api/node.js

@@ -42,7 +42,7 @@ export let transformFromAst = pipeline.transformFromAst.bind(pipeline);
 
 //
 
-export function transformFile(filename, opts, callback) {
+export function transformFile(filename: string, opts?: Object, callback: Function) {
   if (isFunction(opts)) {
     callback = opts;
     opts = {};
@@ -69,7 +69,7 @@ export function transformFile(filename, opts, callback) {
   });
 }
 
-export function transformFileSync(filename, opts = {}) {
+export function transformFileSync(filename: string, opts?: Object = {}): string {
   opts.filename = filename;
   return transform(fs.readFileSync(filename, "utf8"), opts);
 }

packages/babel-core/src/helpers/merge.js

@@ -1,8 +1,6 @@
-
-
 import merge from "lodash/object/merge";
 
-export default function (dest, src) {
+export default function (dest?: Object, src?: Object): ?Object {
   if (!dest || !src) return;
 
   return merge(dest, src, function (a, b) {

packages/babel-core/src/helpers/normalize-ast.js

@@ -1,4 +1,3 @@
-
 import * as t from "babel-types";
 
 /**
@@ -7,7 +6,11 @@ import * as t from "babel-types";
  * - Wrap `Program` node with a `File` node.
  */
 
-export default function (ast, comments, tokens) {
+export default function (
+  ast: Object,
+  comments?: Array<Object>,
+  tokens?: Array<Object>,
+) {
   if (ast) {
     if (ast.type === "Program") {
       return t.file(ast, comments || [], tokens || []);

packages/babel-core/src/helpers/resolve.js

@@ -3,7 +3,7 @@ import path from "path";
 
 let relativeModules = {};
 
-export default function (loc, relative = process.cwd()) {
+export default function (loc: string, relative: string = process.cwd()): ?string {
   // we're in the browser, probably
   if (typeof Module === "object") return null;
 

packages/babel-core/src/store.js

@@ -4,11 +4,13 @@ export default class Store extends Map {
     this.dynamicData = {};
   }
 
+  dynamicData: Object;
+
   setDynamic(key, fn) {
     this.dynamicData[key] = fn;
   }
 
-  get(key) {
+  get(key: string): any {
     if (this.has(key)) {
       return super.get(key);
     } else {

packages/babel-core/src/tools/build-external-helpers.js

@@ -82,7 +82,10 @@ function buildHelpers(body, namespace, whitelist) {
     ));
   });
 }
-export default function (whitelist, outputType = "global") {
+export default function (
+  whitelist?: Array<string>,
+  outputType: "global" | "umd" | "var" = "global",
+) {
   let namespace = t.identifier("babelHelpers");
 
   let builder = function (body) {

packages/babel-core/src/transformation/file/index.js

@@ -1,13 +1,14 @@
+/* global BabelFileResult, BabelParserOptions, BabelFileMetadata */
 /* eslint max-len: 0 */
 
 import getHelper from "babel-helpers";
 import * as metadataVisitor from "./metadata";
 import convertSourceMap from "convert-source-map";
 import OptionManager from "./options/option-manager";
-
+import type Pipeline from "../pipeline";
 import PluginPass from "../plugin-pass";
 import shebangRegex from "shebang-regex";
-import { NodePath, Hub } from "babel-traverse";
+import { NodePath, Hub, Scope } from "babel-traverse";
 import sourceMap from "source-map";
 import generate from "babel-generator";
 import codeFrame from "babel-code-frame";
@@ -39,7 +40,7 @@ let errorVisitor = {
 };
 
 export default class File extends Store {
-  constructor(opts = {}, pipeline) {
+  constructor(opts: Object = {}, pipeline: Pipeline) {
     super();
 
     this.pipeline = pipeline;
@@ -100,9 +101,30 @@ export default class File extends Store {
     this.hub = new Hub(this);
   }
 
+  static helpers: Array<string>;
+
+  pluginVisitors: Array<Object>;
+  pluginPasses: Array<PluginPass>;
+  pipeline: Pipeline;
+  parserOpts: BabelParserOptions;
+  log: Logger;
+  opts: Object;
+  dynamicImportTypes: Object;
+  dynamicImportIds: Object;
+  dynamicImports: Array<Object>;
+  declarations: Object;
+  usedHelpers: Object;
+  path: NodePath;
+  ast: Object;
+  scope: Scope;
+  metadata: BabelFileMetadata;
+  hub: Hub;
+  code: string;
+  shebang: string;
+
   getMetadata() {
     let has = false;
-    for (let node of this.ast.program.body) {
+    for (let node of (this.ast.program.body: Array<Object>)) {
       if (t.isModuleDeclaration(node)) {
         has = true;
         break;
@@ -157,7 +179,7 @@ export default class File extends Store {
       return;
     }
 
-    let plugins = opts.plugins.concat(INTERNAL_PLUGINS);
+    let plugins: Array<[PluginPass, Object]> = opts.plugins.concat(INTERNAL_PLUGINS);
     let currentPluginVisitors = [];
     let currentPluginPasses = [];
 
@@ -177,7 +199,7 @@ export default class File extends Store {
     this.pluginPasses.push(currentPluginPasses);
   }
 
-  getModuleName() {
+  getModuleName(): ?string {
     let opts = this.opts;
     if (!opts.moduleIds) {
       return null;
@@ -221,13 +243,13 @@ export default class File extends Store {
     }
   }
 
-  resolveModuleSource(source) {
+  resolveModuleSource(source: string): string {
     let resolveModuleSource = this.opts.resolveModuleSource;
     if (resolveModuleSource) source = resolveModuleSource(source, this.opts.filename);
     return source;
   }
 
-  addImport(source, imported, name = imported) {
+  addImport(source: string, imported: string, name?: string = imported): Object {
     let alias = `${source}:${imported}`;
     let id = this.dynamicImportIds[alias];
 
@@ -254,7 +276,7 @@ export default class File extends Store {
     return id;
   }
 
-  addHelper(name) {
+  addHelper(name: string): Object {
     let declar = this.declarations[name];
     if (declar) return declar;
 
@@ -293,7 +315,11 @@ export default class File extends Store {
     return uid;
   }
 
-  addTemplateObject(helperName, strings, raw) {
+  addTemplateObject(
+    helperName: string,
+    strings: Array<Object>,
+    raw: Object,
+  ): Object {
     // Generate a unique name based on the string literals so we dedupe
     // identical strings used in the program.
     let stringIds = raw.elements.map(function(string) {
@@ -317,7 +343,7 @@ export default class File extends Store {
     return uid;
   }
 
-  buildCodeFrameError(node, msg, Error = SyntaxError) {
+  buildCodeFrameError(node: Object, msg: string, Error: typeof Error = SyntaxError): Error {
     let loc = node && (node.loc || node._loc);
 
     let err = new Error(msg);
@@ -339,7 +365,7 @@ export default class File extends Store {
     return err;
   }
 
-  mergeSourceMap(map) {
+  mergeSourceMap(map: Object) {
     let inputMap = this.opts.inputSourceMap;
 
     if (inputMap) {
@@ -383,7 +409,7 @@ export default class File extends Store {
     }
   }
 
-  parse(code) {
+  parse(code: string) {
     this.log.debug("Parse start");
     let ast = parse(code, this.parserOpts);
     this.log.debug("Parse stop");
@@ -409,7 +435,7 @@ export default class File extends Store {
     this.log.debug("End set AST");
   }
 
-  transform() {
+  transform(): BabelFileResult {
     // In the "pass per preset" mode, we have grouped passes.
     // Otherwise, there is only one plain pluginPasses array.
     this.pluginPasses.forEach((pluginPasses, index) => {
@@ -423,7 +449,7 @@ export default class File extends Store {
     return this.generate();
   }
 
-  wrap(code, callback) {
+  wrap(code: string, callback: Function): BabelFileResult {
     code = code + "";
 
     try {
@@ -462,7 +488,7 @@ export default class File extends Store {
     }
   }
 
-  addCode(code) {
+  addCode(code: string) {
     code = (code || "") + "";
     code = this.parseInputSourceMap(code);
     this.code = code;
@@ -479,7 +505,7 @@ export default class File extends Store {
     return util.shouldIgnore(opts.filename, opts.ignore, opts.only);
   }
 
-  call(key, pluginPasses) {
+  call(key: "pre" | "post", pluginPasses: Array<PluginPass>) {
     for (let pass of pluginPasses) {
       let plugin = pass.plugin;
       let fn = plugin[key];
@@ -487,7 +513,7 @@ export default class File extends Store {
     }
   }
 
-  parseInputSourceMap(code) {
+  parseInputSourceMap(code: string): string {
     let opts = this.opts;
 
     if (opts.inputSourceMap !== false) {
@@ -509,7 +535,7 @@ export default class File extends Store {
     }
   }
 
-  makeResult({ code, map, ast, ignored }) {
+  makeResult({ code, map, ast, ignored }: BabelFileResult): BabelFileResult {
     let result = {
       metadata: null,
       options:  this.opts,
@@ -534,11 +560,11 @@ export default class File extends Store {
     return result;
   }
 
-  generate() {
+  generate(): BabelFileResult {
     let opts = this.opts;
     let ast  = this.ast;
 
-    let result = { ast };
+    let result: BabelFileResult = { ast };
     if (!opts.code) return this.makeResult(result);
 
     this.log.debug("Generation start");

packages/babel-core/src/transformation/file/logger.js

@@ -1,3 +1,4 @@
+import type File from "./index";
 import buildDebug from "debug/node";
 
 let verboseDebug = buildDebug("babel:verbose");
@@ -6,26 +7,29 @@ let generalDebug = buildDebug("babel");
 let seenDeprecatedMessages = [];
 
 export default class Logger {
-  constructor(file, filename) {
+  constructor(file: File, filename: string) {
     this.filename = filename;
     this.file     = file;
   }
 
-  _buildMessage(msg) {
+  filename: string;
+  file: File;
+
+  _buildMessage(msg: string): string {
     let parts = `[BABEL] ${this.filename}`;
     if (msg) parts += `: ${msg}`;
     return parts;
   }
 
-  warn(msg) {
+  warn(msg: string) {
     console.warn(this._buildMessage(msg));
   }
 
-  error(msg, Constructor = Error) {
+  error(msg: string, Constructor: typeof Error = Error): Error {
     throw new Constructor(this._buildMessage(msg));
   }
 
-  deprecate(msg) {
+  deprecate(msg: string) {
     if (this.file.opts && this.file.opts.suppressDeprecationMessages) return;
 
     msg = this._buildMessage(msg);
@@ -39,15 +43,15 @@ export default class Logger {
     console.error(msg);
   }
 
-  verbose(msg) {
+  verbose(msg: string) {
     if (verboseDebug.enabled) verboseDebug(this._buildMessage(msg));
   }
 
-  debug(msg) {
+  debug(msg: string) {
     if (generalDebug.enabled) generalDebug(this._buildMessage(msg));
   }
 
-  deopt(node, msg) {
+  deopt(node: Object, msg: string) {
     this.debug(msg);
   }
 }

packages/babel-core/src/transformation/file/metadata.js

@@ -21,7 +21,7 @@ export let ImportDeclaration = {
       specifiers
     });
 
-    for (let specifier of path.get("specifiers")) {
+    for (let specifier of (path.get("specifiers"): Array<Object>)) {
       let local = specifier.node.local.name;
 
       if (specifier.isImportDefaultSpecifier()) {
@@ -77,7 +77,7 @@ export function ExportDeclaration(path, file) {
   }
 
   if (path.isExportNamedDeclaration() && node.specifiers) {
-    for (let specifier of node.specifiers) {
+    for (let specifier of (node.specifiers: Array<Object>)) {
       let exported = specifier.exported.name;
       exports.exported.push(exported);
 

packages/babel-core/src/transformation/file/options/index.js

@@ -1,10 +1,9 @@
-
 import * as parsers from "./parsers";
 import config from "./config";
 
 export { config };
 
-export function normaliseOptions(options = {}) {
+export function normaliseOptions(options: Object = {}): Object {
   for (let key in options) {
     let val = options[key];
     if (val == null) continue;

packages/babel-core/src/transformation/file/options/option-manager.js

@@ -1,6 +1,7 @@
 /* eslint max-len: 0 */
 
 import * as context from "../../../api/node";
+import type Logger from "../logger";
 import Plugin from "../../plugin";
 import * as messages from "babel-messages";
 import { normaliseOptions } from "./index";
@@ -32,19 +33,49 @@ function exists(filename) {
   }
 }
 
+type PluginObject = {
+  pre?: Function;
+  post?: Function;
+  manipulateOptions?: Function;
+
+  visitor: ?{
+    [key: string]: Function | {
+      enter?: Function | Array<Function>;
+      exit?: Function | Array<Function>;
+    }
+  };
+};
+
+type MergeOptions = {
+  options?: Object,
+  extending?: Object,
+  alias: string,
+  loc?: string,
+  dirname?: string
+};
+
 export default class OptionManager {
-  constructor(log) {
+  constructor(log?: Logger) {
     this.resolvedConfigs = [];
     this.options = OptionManager.createBareOptions();
     this.log = log;
   }
 
+  resolvedConfigs: Array<string>;
+  options: Object;
+  log: ?Logger;
+
+  static memoisedPlugins: Array<{
+    container: Function;
+    plugin: Plugin;
+  }>;
+
   static memoisePluginContainer(fn, loc, i, alias) {
-    for (let cache of OptionManager.memoisedPlugins) {
+    for (let cache of (OptionManager.memoisedPlugins: Array<Object>)) {
       if (cache.container === fn) return cache.plugin;
     }
 
-    let obj;
+    let obj: ?PluginObject;
 
     if (typeof fn === "function") {
       obj = fn(context);
@@ -125,7 +156,7 @@ export default class OptionManager {
     });
   }
 
-  addConfig(loc, key, json = json5) {
+  addConfig(loc: string, key?: string, json = json5): boolean {
     if (this.resolvedConfigs.indexOf(loc) >= 0) {
       return false;
     }
@@ -167,7 +198,7 @@ export default class OptionManager {
     alias,
     loc,
     dirname
-  }) {
+  }: MergeOptions) {
     alias = alias || "foreign";
     if (!rawOpts) return;
 
@@ -272,7 +303,7 @@ export default class OptionManager {
    * Merges all presets into the main options in case we are not in the
    * "pass per preset" mode. Otherwise, options are calculated per preset.
    */
-  mergePresets(presets, dirname) {
+  mergePresets(presets: Array<string | Object>, dirname: string) {
     this.resolvePresets(presets, dirname, (presetOpts, presetLoc) => {
       this.mergeOptions({
         options: presetOpts,
@@ -287,7 +318,7 @@ export default class OptionManager {
    * Resolves presets options which can be either direct object data,
    * or a module name to require.
    */
-  resolvePresets(presets, dirname, onResolve) {
+  resolvePresets(presets: Array<string | Object>, dirname: string, onResolve?) {
     return presets.map((val) => {
       if (typeof val === "string") {
         let presetLoc = resolve(`babel-preset-${val}`, dirname) || resolve(val, dirname);
@@ -376,7 +407,7 @@ export default class OptionManager {
     }
   }
 
-  init(opts = {}) {
+  init(opts: Object = {}): Object {
     let filename = opts.filename;
 
     // resolve all .babelrc files

packages/babel-core/src/transformation/file/options/parsers.js

@@ -1,18 +1,16 @@
-
-
 import slash from "slash";
 import * as util from "../../../util";
 
 export let filename = slash;
 
-export function boolean(val) {
+export function boolean(val: any): boolean {
   return !!val;
 }
 
-export function booleanString(val) {
+export function booleanString(val: any): boolean | any {
   return util.booleanify(val);
 }
 
-export function list(val) {
+export function list(val: any): Array<string> {
   return util.list(val);
 }

packages/babel-core/src/transformation/internal-plugins/block-hoist.js

@@ -1,4 +1,3 @@
-
 import Plugin from "../plugin";
 import sortBy from "lodash/collection/sortBy";
 

packages/babel-core/src/transformation/pipeline.js

@@ -1,15 +1,16 @@
+/* global BabelFileResult, BabelFileMetadata */
 import normalizeAst from "../helpers/normalize-ast";
 import Plugin from "./plugin";
 import File from "./file";
 
 export default class Pipeline {
-  lint(code, opts = {}) {
+  lint(code: string, opts?: Object = {}): BabelFileResult {
     opts.code = false;
     opts.mode = "lint";
     return this.transform(code, opts);
   }
 
-  pretransform(code, opts) {
+  pretransform(code: string, opts?: Object): BabelFileResult {
     let file = new File(opts, this);
     return file.wrap(code, function () {
       file.addCode(code);
@@ -18,7 +19,7 @@ export default class Pipeline {
     });
   }
 
-  transform(code, opts) {
+  transform(code: string, opts?: Object): BabelFileResult {
     let file = new File(opts, this);
     return file.wrap(code, function () {
       file.addCode(code);
@@ -27,7 +28,7 @@ export default class Pipeline {
     });
   }
 
-  analyse(code, opts = {}, visitor) {
+  analyse(code: string, opts: Object = {}, visitor?: Object): ?BabelFileMetadata {
     opts.code = false;
     if (visitor) {
       opts.plugins = opts.plugins || [];
@@ -36,7 +37,7 @@ export default class Pipeline {
     return this.transform(code, opts).metadata;
   }
 
-  transformFromAst(ast, code, opts) {
+  transformFromAst(ast: Object, code: string, opts: Object): BabelFileResult {
     ast = normalizeAst(ast);
 
     let file = new File(opts, this);

packages/babel-core/src/transformation/plugin-pass.js

@@ -1,14 +1,20 @@
+import type Plugin from "./plugin";
 import Store from "../store";
 import traverse from "babel-traverse";
+import File from "./file";
 
 export default class PluginPass extends Store {
-  constructor(file, plugin, options = {}) {
+  constructor(file: File, plugin: Plugin, options: Object = {}) {
     super();
     this.plugin = plugin;
     this.file   = file;
     this.opts   = options;
   }
 
+  plugin: Plugin;
+  file: File;
+  opts: Object;
+
   transform() {
     let file = this.file;
     file.log.debug(`Start transformer ${this.key}`);

packages/babel-core/src/transformation/plugin.js

@@ -10,7 +10,7 @@ import clone from "lodash/lang/clone";
 const GLOBAL_VISITOR_PROPS = ["enter", "exit"];
 
 export default class Plugin extends Store {
-  constructor(plugin, key) {
+  constructor(plugin: Object, key?: string) {
     super();
 
     this.initialized = false;
@@ -23,6 +23,13 @@ export default class Plugin extends Store {
     this.visitor           = this.normaliseVisitor(clone(this.take("visitor")) || {});
   }
 
+  initialized: boolean;
+  raw: Object;
+  manipulateOptions: ?Function;
+  post: ?Function;
+  pre: ?Function;
+  visitor: Object;
+
   take(key) {
     let val = this.raw[key];
     delete this.raw[key];
@@ -33,7 +40,7 @@ export default class Plugin extends Store {
     if (!target[key]) return this[key];
     if (!this[key]) return target[key];
 
-    let fns = [target[key], this[key]];
+    let fns: Array<?Function> = [target[key], this[key]];
 
     return function (...args) {
       let val;
@@ -47,7 +54,7 @@ export default class Plugin extends Store {
     };
   }
 
-  maybeInherit(loc) {
+  maybeInherit(loc: string) {
     let inherits = this.take("inherits");
     if (!inherits) return;
 
@@ -64,7 +71,7 @@ export default class Plugin extends Store {
    * position on disk and how it was specified.
    */
 
-  init(loc, i) {
+  init(loc: string, i: number) {
     if (this.initialized) return;
     this.initialized = true;
 
@@ -75,7 +82,7 @@ export default class Plugin extends Store {
     }
   }
 
-  normaliseVisitor(visitor) {
+  normaliseVisitor(visitor: Object): Object {
     for (let key of GLOBAL_VISITOR_PROPS) {
       if (visitor[key]) {
         throw new Error("Plugins aren't allowed to specify catch-all enter/exit handlers. Please target individual nodes.");

packages/babel-core/src/util.js

@@ -1,4 +1,3 @@
-
 import escapeRegExp from "lodash/string/escapeRegExp";
 import startsWith from "lodash/string/startsWith";
 import isBoolean from "lodash/lang/isBoolean";
@@ -15,7 +14,7 @@ export { inherits, inspect } from "util";
  * Test if a filename ends with a compilable extension.
  */
 
-export function canCompile(filename, altExts) {
+export function canCompile(filename: string, altExts?: Array<string>): boolean {
   let exts = altExts || canCompile.EXTENSIONS;
   let ext = path.extname(filename);
   return contains(exts, ext);
@@ -31,7 +30,7 @@ canCompile.EXTENSIONS = [".js", ".jsx", ".es6", ".es"];
  * Create an array from any value, splitting strings by ",".
  */
 
-export function list(val) {
+export function list(val?: string): Array<string> {
   if (!val) {
     return [];
   } else if (Array.isArray(val)) {
@@ -47,7 +46,7 @@ export function list(val) {
  * Create a RegExp from a string, array, or regexp.
  */
 
-export function regexify(val) {
+export function regexify(val: any): RegExp {
   if (!val) {
     return new RegExp(/.^/);
   }
@@ -79,7 +78,7 @@ export function regexify(val) {
  * Create an array from a boolean, string, or array, mapped by and optional function.
  */
 
-export function arrayify(val, mapFn) {
+export function arrayify(val: any, mapFn?: Function): Array<any> {
   if (!val) return [];
   if (isBoolean(val)) return arrayify([val], mapFn);
   if (isString(val)) return arrayify(list(val), mapFn);
@@ -96,7 +95,7 @@ export function arrayify(val, mapFn) {
  * Makes boolean-like strings into booleans.
  */
 
-export function booleanify(val) {
+export function booleanify(val: any): boolean | any {
   if (val === "true" || val == 1) {
     return true;
   }
@@ -112,7 +111,11 @@ export function booleanify(val) {
  * Tests if a filename should be ignored based on "ignore" and "only" options.
  */
 
-export function shouldIgnore(filename, ignore = [], only) {
+export function shouldIgnore(
+  filename: string,
+  ignore: Array<RegExp | Function> = [],
+  only?: Array<RegExp | Function>,
+): boolean {
   filename = slash(filename);
 
   if (only) {
@@ -134,7 +137,7 @@ export function shouldIgnore(filename, ignore = [], only) {
  * Otherwise returns result of matching pattern Regex with filename.
  */
 
-function _shouldIgnore(pattern, filename) {
+function _shouldIgnore(pattern: Function | RegExp, filename: string) {
   if (typeof pattern === "function") {
     return pattern(filename);
   } else {

packages/babel-generator/src/buffer.js

@@ -1,4 +1,4 @@
-
+import type Position from "./position";
 import repeating from "repeating";
 import trimRight from "trim-right";
 
@@ -7,7 +7,7 @@ import trimRight from "trim-right";
  */
 
 export default class Buffer {
-  constructor(position, format) {
+  constructor(position: Position, format: Object) {
     this.printedCommentStarts = {};
     this.parenPushNewlineState = null;
     this.position = position;
@@ -21,11 +21,19 @@ export default class Buffer {
     this.last = "";
   }
 
+  printedCommentStarts: Object;
+  parenPushNewlineState: ?Object;
+  position: Position;
+  _indent: number;
+  format: Object;
+  buf: string;
+  last: string;
+
   /**
    * Description
    */
 
-  catchUp(node) {
+  catchUp(node: Object) {
     // catch up to this nodes newline if we're behind
     if (node.loc && this.format.retainLines && this.buf) {
       while (this.position.line < node.loc.start.line) {
@@ -38,7 +46,7 @@ export default class Buffer {
    * Get the current trimmed buffer.
    */
 
-  get() {
+  get(): string {
     return trimRight(this.buf);
   }
 
@@ -46,7 +54,7 @@ export default class Buffer {
    * Get the current indent.
    */
 
-  getIndent() {
+  getIndent(): string {
     if (this.format.compact || this.format.concise) {
       return "";
     } else {
@@ -58,7 +66,7 @@ export default class Buffer {
    * Get the current indent size.
    */
 
-  indentSize() {
+  indentSize(): number {
     return this.getIndent().length;
   }
 
@@ -110,7 +118,7 @@ export default class Buffer {
    * Add a keyword to the buffer.
    */
 
-  keyword(name) {
+  keyword(name: string) {
     this.push(name);
     this.space();
   }
@@ -119,7 +127,7 @@ export default class Buffer {
    * Add a space to the buffer unless it is compact (override with force).
    */
 
-  space(force) {
+  space(force?: boolean) {
     if (!force && this.format.compact) return;
 
     if (force || this.buf && !this.isLast(" ") && !this.isLast("\n")) {
@@ -131,12 +139,12 @@ export default class Buffer {
    * Remove the last character.
    */
 
-  removeLast(cha) {
+  removeLast(cha: string) {
     if (this.format.compact) return;
     return this._removeLast(cha);
   }
 
-  _removeLast(cha) {
+  _removeLast(cha: string) {
     if (!this._isLast(cha)) return;
     this.buf = this.buf.slice(0, -1);
     this.last = this.buf[this.buf.length - 1];
@@ -159,7 +167,7 @@ export default class Buffer {
    *  `undefined` will be returned and not `foo` due to the terminator.
    */
 
-  startTerminatorless() {
+  startTerminatorless(): Object {
     return this.parenPushNewlineState = {
       printed: false
     };
@@ -169,7 +177,7 @@ export default class Buffer {
    * Print an ending parentheses if a starting one has been printed.
    */
 
-  endTerminatorless(state) {
+  endTerminatorless(state: Object) {
     if (state.printed) {
       this.dedent();
       this.newline();
@@ -182,7 +190,7 @@ export default class Buffer {
    * Strips multiple newlines if removeLast is true.
    */
 
-  newline(i, removeLast) {
+  newline(i?: boolean | number, removeLast?: boolean) {
     if (this.format.retainLines || this.format.compact) return;
 
     if (this.format.concise) {
@@ -226,7 +234,7 @@ export default class Buffer {
    * Push a string to the buffer, maintaining indentation and newlines.
    */
 
-  push(str, noIndent) {
+  push(str: string, noIndent?: boolean) {
     if (!this.format.compact && this._indent && !noIndent && str !== "\n") {
       // we have an indent level and we aren't pushing a newline
       let indent = this.getIndent();
@@ -245,7 +253,7 @@ export default class Buffer {
    * Push a string to the buffer.
    */
 
-  _push(str) {
+  _push(str: string): void {
     // see startTerminatorless() instance method
     let parenPushNewlineState = this.parenPushNewlineState;
     if (parenPushNewlineState) {
@@ -278,7 +286,7 @@ export default class Buffer {
    * Test if the buffer ends with a string.
    */
 
-  endsWith(str) {
+  endsWith(str: string): boolean {
     if (str.length === 1) {
       return this.last === str;
     } else {
@@ -290,12 +298,12 @@ export default class Buffer {
    * Test if a character is last in the buffer.
    */
 
-  isLast(cha) {
+  isLast(cha: string): boolean {
     if (this.format.compact) return false;
     return this._isLast(cha);
   }
 
-  _isLast(cha) {
+  _isLast(cha: string): boolean {
     let last = this.last;
 
     if (Array.isArray(cha)) {

packages/babel-generator/src/generators/base.js

@@ -1,9 +1,8 @@
-
-export function File(node) {
+export function File(node: Object) {
   this.print(node.program, node);
 }
 
-export function Program(node) {
+export function Program(node: Object) {
   this.printInnerComments(node, false);
 
   this.printSequence(node.directives, node);
@@ -12,7 +11,7 @@ export function Program(node) {
   this.printSequence(node.body, node);
 }
 
-export function BlockStatement(node) {
+export function BlockStatement(node: Object) {
   this.push("{");
   this.printInnerComments(node);
   if (node.body.length) {
@@ -31,11 +30,11 @@ export function BlockStatement(node) {
 
 export function Noop() {}
 
-export function Directive(node) {
+export function Directive(node: Object) {
   this.print(node.value, node);
   this.semicolon();
 }
 
-export function DirectiveLiteral(node) {
+export function DirectiveLiteral(node: Object) {
   this.push(this._stringLiteral(node.value));
 }

packages/babel-generator/src/generators/classes.js

@@ -1,5 +1,4 @@
-
-export function ClassDeclaration(node) {
+export function ClassDeclaration(node: Object) {
   this.printJoin(node.decorators, node, { separator: "" });
   this.push("class");
 
@@ -27,7 +26,7 @@ export function ClassDeclaration(node) {
 
 export { ClassDeclaration as ClassExpression };
 
-export function ClassBody(node) {
+export function ClassBody(node: Object) {
   this.push("{");
   this.printInnerComments(node);
   if (node.body.length === 0) {
@@ -43,7 +42,7 @@ export function ClassBody(node) {
   }
 }
 
-export function ClassProperty(node) {
+export function ClassProperty(node: Object) {
   this.printJoin(node.decorators, node, { separator: "" });
 
   if (node.static) this.push("static ");
@@ -58,7 +57,7 @@ export function ClassProperty(node) {
   this.semicolon();
 }
 
-export function ClassMethod(node) {
+export function ClassMethod(node: Object) {
   this.printJoin(node.decorators, node, { separator: "" });
 
   if (node.static) {

packages/babel-generator/src/generators/expressions.js

@@ -9,7 +9,7 @@ const SCIENTIFIC_NOTATION = /e/i;
 const ZERO_DECIMAL_INTEGER = /\.0+$/;
 const NON_DECIMAL_LITERAL = /^0[box]/;
 
-export function UnaryExpression(node) {
+export function UnaryExpression(node: Object) {
   let needsSpace = /[a-z]$/.test(node.operator);
   let arg = node.argument;
 
@@ -26,19 +26,19 @@ export function UnaryExpression(node) {
   this.print(node.argument, node);
 }
 
-export function DoExpression(node) {
+export function DoExpression(node: Object) {
   this.push("do");
   this.space();
   this.print(node.body, node);
 }
 
-export function ParenthesizedExpression(node) {
+export function ParenthesizedExpression(node: Object) {
   this.push("(");
   this.print(node.expression, node);
   this.push(")");
 }
 
-export function UpdateExpression(node) {
+export function UpdateExpression(node: Object) {
   if (node.prefix) {
     this.push(node.operator);
     this.print(node.argument, node);
@@ -48,7 +48,7 @@ export function UpdateExpression(node) {
   }
 }
 
-export function ConditionalExpression(node) {
+export function ConditionalExpression(node: Object) {
   this.print(node.test, node);
   this.space();
   this.push("?");
@@ -60,7 +60,7 @@ export function ConditionalExpression(node) {
   this.print(node.alternate, node);
 }
 
-export function NewExpression(node, parent) {
+export function NewExpression(node: Object, parent: Object) {
   this.push("new ");
   this.print(node.callee, node);
   if (node.arguments.length === 0 && this.format.minified &&
@@ -73,7 +73,7 @@ export function NewExpression(node, parent) {
   this.push(")");
 }
 
-export function SequenceExpression(node) {
+export function SequenceExpression(node: Object) {
   this.printList(node.expressions, node);
 }
 
@@ -85,13 +85,13 @@ export function Super() {
   this.push("super");
 }
 
-export function Decorator(node) {
+export function Decorator(node: Object) {
   this.push("@");
   this.print(node.expression, node);
   this.newline();
 }
 
-export function CallExpression(node) {
+export function CallExpression(node: Object) {
   this.print(node.callee, node);
   if (node.loc) this.printAuxAfterComment();
 
@@ -116,8 +116,8 @@ export function CallExpression(node) {
   this.push(")");
 }
 
-function buildYieldAwait(keyword) {
-  return function (node) {
+function buildYieldAwait(keyword: string) {
+  return function (node: Object) {
     this.push(keyword);
 
     if (node.delegate) {
@@ -141,12 +141,12 @@ export function EmptyStatement() {
   this.semicolon();
 }
 
-export function ExpressionStatement(node) {
+export function ExpressionStatement(node: Object) {
   this.print(node.expression, node);
   this.semicolon();
 }
 
-export function AssignmentPattern(node) {
+export function AssignmentPattern(node: Object) {
   this.print(node.left, node);
   this.space();
   this.push("=");
@@ -154,7 +154,7 @@ export function AssignmentPattern(node) {
   this.print(node.right, node);
 }
 
-export function AssignmentExpression(node, parent) {
+export function AssignmentExpression(node: Object, parent: Object) {
   // Somewhere inside a for statement `init` node but doesn't usually
   // needs a paren except for `in` expressions: `for (a in b ? a : b;;)`
   let parens = this._inForStatementInitCounter && node.operator === "in" &&
@@ -195,7 +195,7 @@ export function AssignmentExpression(node, parent) {
   }
 }
 
-export function BindExpression(node) {
+export function BindExpression(node: Object) {
   this.print(node.object, node);
   this.push("::");
   this.print(node.callee, node);
@@ -206,7 +206,7 @@ export {
   AssignmentExpression as LogicalExpression
 };
 
-export function MemberExpression(node) {
+export function MemberExpression(node: Object) {
   this.print(node.object, node);
 
   if (!node.computed && t.isMemberExpression(node.property)) {
@@ -239,7 +239,7 @@ export function MemberExpression(node) {
   }
 }
 
-export function MetaProperty(node) {
+export function MetaProperty(node: Object) {
   this.print(node.meta, node);
   this.push(".");
   this.print(node.property, node);

packages/babel-generator/src/generators/flow.js

@@ -6,7 +6,7 @@ export function AnyTypeAnnotation() {
   this.push("any");
 }
 
-export function ArrayTypeAnnotation(node) {
+export function ArrayTypeAnnotation(node: Object) {
   this.print(node.elementType, node);
   this.push("[");
   this.push("]");
@@ -16,7 +16,7 @@ export function BooleanTypeAnnotation() {
   this.push("bool");
 }
 
-export function BooleanLiteralTypeAnnotation(node) {
+export function BooleanLiteralTypeAnnotation(node: Object) {
   this.push(node.value ? "true" : "false");
 }
 
@@ -24,36 +24,36 @@ export function NullLiteralTypeAnnotation() {
   this.push("null");
 }
 
-export function DeclareClass(node) {
+export function DeclareClass(node: Object) {
   this.push("declare class ");
   this._interfaceish(node);
 }
 
-export function DeclareFunction(node) {
+export function DeclareFunction(node: Object) {
   this.push("declare function ");
   this.print(node.id, node);
   this.print(node.id.typeAnnotation.typeAnnotation, node);
   this.semicolon();
 }
 
-export function DeclareInterface(node) {
+export function DeclareInterface(node: Object) {
   this.push("declare ");
   this.InterfaceDeclaration(node);
 }
 
-export function DeclareModule(node) {
+export function DeclareModule(node: Object) {
   this.push("declare module ");
   this.print(node.id, node);
   this.space();
   this.print(node.body, node);
 }
 
-export function DeclareTypeAlias(node) {
+export function DeclareTypeAlias(node: Object) {
   this.push("declare ");
   this.TypeAlias(node);
 }
 
-export function DeclareVariable(node) {
+export function DeclareVariable(node: Object) {
   this.push("declare var ");
   this.print(node.id, node);
   this.print(node.id.typeAnnotation, node);
@@ -64,7 +64,7 @@ export function ExistentialTypeParam() {
   this.push("*");
 }
 
-export function FunctionTypeAnnotation(node, parent) {
+export function FunctionTypeAnnotation(node: Object, parent: Object) {
   this.print(node.typeParameters, node);
   this.push("(");
   this.printList(node.params, node);
@@ -92,7 +92,7 @@ export function FunctionTypeAnnotation(node, parent) {
   this.print(node.returnType, node);
 }
 
-export function FunctionTypeParam(node) {
+export function FunctionTypeParam(node: Object) {
   this.print(node.name, node);
   if (node.optional) this.push("?");
   this.push(":");
@@ -100,14 +100,14 @@ export function FunctionTypeParam(node) {
   this.print(node.typeAnnotation, node);
 }
 
-export function InterfaceExtends(node) {
+export function InterfaceExtends(node: Object) {
   this.print(node.id, node);
   this.print(node.typeParameters, node);
 }
 
 export { InterfaceExtends as ClassImplements, InterfaceExtends as GenericTypeAnnotation };
 
-export function _interfaceish(node) {
+export function _interfaceish(node: Object) {
   this.print(node.id, node);
   this.print(node.typeParameters, node);
   if (node.extends.length) {
@@ -122,12 +122,12 @@ export function _interfaceish(node) {
   this.print(node.body, node);
 }
 
-export function InterfaceDeclaration(node) {
+export function InterfaceDeclaration(node: Object) {
   this.push("interface ");
   this._interfaceish(node);
 }
 
-export function IntersectionTypeAnnotation(node) {
+export function IntersectionTypeAnnotation(node: Object) {
   this.printJoin(node.types, node, { separator: " & " });
 }
 
@@ -135,7 +135,7 @@ export function MixedTypeAnnotation() {
   this.push("mixed");
 }
 
-export function NullableTypeAnnotation(node) {
+export function NullableTypeAnnotation(node: Object) {
   this.push("?");
   this.print(node.typeAnnotation, node);
 }
@@ -146,7 +146,7 @@ export function NumberTypeAnnotation() {
   this.push("number");
 }
 
-export function StringLiteralTypeAnnotation(node) {
+export function StringLiteralTypeAnnotation(node: Object) {
   this.push(this._stringLiteral(node.value));
 }
 
@@ -158,18 +158,18 @@ export function ThisTypeAnnotation() {
   this.push("this");
 }
 
-export function TupleTypeAnnotation(node) {
+export function TupleTypeAnnotation(node: Object) {
   this.push("[");
   this.printJoin(node.types, node, { separator: ", " });
   this.push("]");
 }
 
-export function TypeofTypeAnnotation(node) {
+export function TypeofTypeAnnotation(node: Object) {
   this.push("typeof ");
   this.print(node.argument, node);
 }
 
-export function TypeAlias(node) {
+export function TypeAlias(node: Object) {
   this.push("type ");
   this.print(node.id, node);
   this.print(node.typeParameters, node);
@@ -180,18 +180,18 @@ export function TypeAlias(node) {
   this.semicolon();
 }
 
-export function TypeAnnotation(node) {
+export function TypeAnnotation(node: Object) {
   this.push(":");
   this.space();
   if (node.optional) this.push("?");
   this.print(node.typeAnnotation, node);
 }
 
-export function TypeParameterInstantiation(node) {
+export function TypeParameterInstantiation(node: Object) {
   this.push("<");
   this.printJoin(node.params, node, {
     separator: ", ",
-    iterator: (node) => {
+    iterator: (node: Object) => {
       this.print(node.typeAnnotation, node);
     }
   });
@@ -200,7 +200,7 @@ export function TypeParameterInstantiation(node) {
 
 export { TypeParameterInstantiation as TypeParameterDeclaration };
 
-export function ObjectTypeAnnotation(node) {
+export function ObjectTypeAnnotation(node: Object) {
   this.push("{");
   let props = node.properties.concat(node.callProperties, node.indexers);
 
@@ -224,12 +224,12 @@ export function ObjectTypeAnnotation(node) {
   this.push("}");
 }
 
-export function ObjectTypeCallProperty(node) {
+export function ObjectTypeCallProperty(node: Object) {
   if (node.static) this.push("static ");
   this.print(node.value, node);
 }
 
-export function ObjectTypeIndexer(node) {
+export function ObjectTypeIndexer(node: Object) {
   if (node.static) this.push("static ");
   this.push("[");
   this.print(node.id, node);
@@ -242,7 +242,7 @@ export function ObjectTypeIndexer(node) {
   this.print(node.value, node);
 }
 
-export function ObjectTypeProperty(node) {
+export function ObjectTypeProperty(node: Object) {
   if (node.static) this.push("static ");
   this.print(node.key, node);
   if (node.optional) this.push("?");
@@ -253,17 +253,17 @@ export function ObjectTypeProperty(node) {
   this.print(node.value, node);
 }
 
-export function QualifiedTypeIdentifier(node) {
+export function QualifiedTypeIdentifier(node: Object) {
   this.print(node.qualification, node);
   this.push(".");
   this.print(node.id, node);
 }
 
-export function UnionTypeAnnotation(node) {
+export function UnionTypeAnnotation(node: Object) {
   this.printJoin(node.types, node, { separator: " | " });
 }
 
-export function TypeCastExpression(node) {
+export function TypeCastExpression(node: Object) {
   this.push("(");
   this.print(node.expression, node);
   this.print(node.typeAnnotation, node);

packages/babel-generator/src/generators/jsx.js

@@ -1,6 +1,4 @@
-
-
-export function JSXAttribute(node) {
+export function JSXAttribute(node: Object) {
   this.print(node.name, node);
   if (node.value) {
     this.push("=");
@@ -8,45 +6,45 @@ export function JSXAttribute(node) {
   }
 }
 
-export function JSXIdentifier(node) {
+export function JSXIdentifier(node: Object) {
   this.push(node.name);
 }
 
-export function JSXNamespacedName(node) {
+export function JSXNamespacedName(node: Object) {
   this.print(node.namespace, node);
   this.push(":");
   this.print(node.name, node);
 }
 
-export function JSXMemberExpression(node) {
+export function JSXMemberExpression(node: Object) {
   this.print(node.object, node);
   this.push(".");
   this.print(node.property, node);
 }
 
-export function JSXSpreadAttribute(node) {
+export function JSXSpreadAttribute(node: Object) {
   this.push("{...");
   this.print(node.argument, node);
   this.push("}");
 }
 
-export function JSXExpressionContainer(node) {
+export function JSXExpressionContainer(node: Object) {
   this.push("{");
   this.print(node.expression, node);
   this.push("}");
 }
 
-export function JSXText(node) {
+export function JSXText(node: Object) {
   this.push(node.value, true);
 }
 
-export function JSXElement(node) {
+export function JSXElement(node: Object) {
   let open = node.openingElement;
   this.print(open, node);
   if (open.selfClosing) return;
 
   this.indent();
-  for (let child of node.children) {
+  for (let child of (node.children: Array<Object>)) {
     this.print(child, node);
   }
   this.dedent();
@@ -54,7 +52,7 @@ export function JSXElement(node) {
   this.print(node.closingElement, node);
 }
 
-export function JSXOpeningElement(node) {
+export function JSXOpeningElement(node: Object) {
   this.push("<");
   this.print(node.name, node);
   if (node.attributes.length > 0) {
@@ -64,7 +62,7 @@ export function JSXOpeningElement(node) {
   this.push(node.selfClosing ? " />" : ">");
 }
 
-export function JSXClosingElement(node) {
+export function JSXClosingElement(node: Object) {
   this.push("</");
   this.print(node.name, node);
   this.push(">");

packages/babel-generator/src/generators/methods.js

@@ -1,8 +1,6 @@
-
-
 import * as t from "babel-types";
 
-export function _params(node) {
+export function _params(node: Object) {
   this.print(node.typeParameters, node);
   this.push("(");
   this.printList(node.params, node, {
@@ -18,9 +16,9 @@ export function _params(node) {
   }
 }
 
-export function _method(node) {
+export function _method(node: Object) {
   let kind = node.kind;
-  let key = node.key;
+  let key  = node.key;
 
   if (kind === "method" || kind === "init") {
     if (node.generator) {
@@ -47,7 +45,7 @@ export function _method(node) {
   this.print(node.body, node);
 }
 
-export function FunctionExpression(node) {
+export function FunctionExpression(node: Object) {
   if (node.async) this.push("async ");
   this.push("function");
   if (node.generator) this.push("*");
@@ -66,7 +64,7 @@ export function FunctionExpression(node) {
 
 export { FunctionExpression as FunctionDeclaration };
 
-export function ArrowFunctionExpression(node) {
+export function ArrowFunctionExpression(node: Object) {
   if (node.async) this.push("async ");
 
   if (node.params.length === 1 && t.isIdentifier(node.params[0])) {

packages/babel-generator/src/generators/modules.js

@@ -1,7 +1,6 @@
-
 import * as t from "babel-types";
 
-export function ImportSpecifier(node) {
+export function ImportSpecifier(node: Object) {
   this.print(node.imported, node);
   if (node.local && node.local.name !== node.imported.name) {
     this.push(" as ");
@@ -9,15 +8,15 @@ export function ImportSpecifier(node) {
   }
 }
 
-export function ImportDefaultSpecifier(node) {
+export function ImportDefaultSpecifier(node: Object) {
   this.print(node.local, node);
 }
 
-export function ExportDefaultSpecifier(node) {
+export function ExportDefaultSpecifier(node: Object) {
   this.print(node.exported, node);
 }
 
-export function ExportSpecifier(node) {
+export function ExportSpecifier(node: Object) {
   this.print(node.local, node);
   if (node.exported && node.local.name !== node.exported.name) {
     this.push(" as ");
@@ -25,12 +24,12 @@ export function ExportSpecifier(node) {
   }
 }
 
-export function ExportNamespaceSpecifier(node) {
+export function ExportNamespaceSpecifier(node: Object) {
   this.push("* as ");
   this.print(node.exported, node);
 }
 
-export function ExportAllDeclaration(node) {
+export function ExportAllDeclaration(node: Object) {
   this.push("export *");
   if (node.exported) {
     this.push(" as ");
@@ -51,7 +50,7 @@ export function ExportDefaultDeclaration() {
   ExportDeclaration.apply(this, arguments);
 }
 
-function ExportDeclaration(node) {
+function ExportDeclaration(node: Object) {
   if (node.declaration) {
     let declar = node.declaration;
     this.print(declar, node);
@@ -97,7 +96,7 @@ function ExportDeclaration(node) {
   this.ensureSemicolon();
 }
 
-export function ImportDeclaration(node) {
+export function ImportDeclaration(node: Object) {
   this.push("import ");
 
   if (node.importKind === "type" || node.importKind === "typeof") {
@@ -134,7 +133,7 @@ export function ImportDeclaration(node) {
   this.semicolon();
 }
 
-export function ImportNamespaceSpecifier(node) {
+export function ImportNamespaceSpecifier(node: Object) {
   this.push("* as ");
   this.print(node.local, node);
 }

packages/babel-generator/src/generators/statements.js

@@ -3,7 +3,7 @@ import * as t from "babel-types";
 
 const NON_ALPHABETIC_UNARY_OPERATORS = t.UPDATE_OPERATORS.concat(t.NUMBER_UNARY_OPERATORS).concat(["!"]);
 
-export function WithStatement(node) {
+export function WithStatement(node: Object) {
   this.keyword("with");
   this.push("(");
   this.print(node.object, node);
@@ -11,7 +11,7 @@ export function WithStatement(node) {
   this.printBlock(node);
 }
 
-export function IfStatement(node) {
+export function IfStatement(node: Object) {
   this.keyword("if");
   this.push("(");
   this.print(node.test, node);
@@ -46,7 +46,7 @@ function getLastStatement(statement) {
   return getLastStatement(statement.body);
 }
 
-export function ForStatement(node) {
+export function ForStatement(node: Object) {
   this.keyword("for");
   this.push("(");
 
@@ -70,7 +70,7 @@ export function ForStatement(node) {
   this.printBlock(node);
 }
 
-export function WhileStatement(node) {
+export function WhileStatement(node: Object) {
   this.keyword("while");
   this.push("(");
   this.print(node.test, node);
@@ -79,7 +79,7 @@ export function WhileStatement(node) {
 }
 
 let buildForXStatement = function (op) {
-  return function (node) {
+  return function (node: Object) {
     this.keyword("for");
     this.push("(");
     this.print(node.left, node);
@@ -93,7 +93,7 @@ let buildForXStatement = function (op) {
 export let ForInStatement = buildForXStatement("in");
 export let ForOfStatement = buildForXStatement("of");
 
-export function DoWhileStatement(node) {
+export function DoWhileStatement(node: Object) {
   this.push("do ");
   this.print(node.body, node);
   this.space();
@@ -104,7 +104,7 @@ export function DoWhileStatement(node) {
 }
 
 function buildLabelStatement(prefix, key = "label") {
-  return function (node) {
+  return function (node: Object) {
     this.push(prefix);
 
     let label = node[key];
@@ -130,13 +130,13 @@ export let ReturnStatement   = buildLabelStatement("return", "argument");
 export let BreakStatement    = buildLabelStatement("break");
 export let ThrowStatement    = buildLabelStatement("throw", "argument");
 
-export function LabeledStatement(node) {
+export function LabeledStatement(node: Object) {
   this.print(node.label, node);
   this.push(": ");
   this.print(node.body, node);
 }
 
-export function TryStatement(node) {
+export function TryStatement(node: Object) {
   this.keyword("try");
   this.print(node.block, node);
   this.space();
@@ -157,7 +157,7 @@ export function TryStatement(node) {
   }
 }
 
-export function CatchClause(node) {
+export function CatchClause(node: Object) {
   this.keyword("catch");
   this.push("(");
   this.print(node.param, node);
@@ -166,7 +166,7 @@ export function CatchClause(node) {
   this.print(node.body, node);
 }
 
-export function SwitchStatement(node) {
+export function SwitchStatement(node: Object) {
   this.keyword("switch");
   this.push("(");
   this.print(node.discriminant, node);
@@ -184,7 +184,7 @@ export function SwitchStatement(node) {
   this.push("}");
 }
 
-export function SwitchCase(node) {
+export function SwitchCase(node: Object) {
   if (node.test) {
     this.push("case ");
     this.print(node.test, node);
@@ -203,13 +203,13 @@ export function DebuggerStatement() {
   this.push("debugger;");
 }
 
-export function VariableDeclaration(node, parent) {
+export function VariableDeclaration(node: Object, parent: Object) {
   this.push(node.kind + " ");
 
   let hasInits = false;
   // don't add whitespace to loop heads
   if (!t.isFor(parent)) {
-    for (let declar of node.declarations) {
+    for (let declar of (node.declarations: Array<Object>)) {
       if (declar.init) {
         // has an init so let's split it up over multiple lines
         hasInits = true;
@@ -246,7 +246,7 @@ export function VariableDeclaration(node, parent) {
   this.semicolon();
 }
 
-export function VariableDeclarator(node) {
+export function VariableDeclarator(node: Object) {
   this.print(node.id, node);
   this.print(node.id.typeAnnotation, node);
   if (node.init) {

packages/babel-generator/src/generators/template-literals.js

@@ -1,14 +1,13 @@
-
-export function TaggedTemplateExpression(node) {
+export function TaggedTemplateExpression(node: Object) {
   this.print(node.tag, node);
   this.print(node.quasi, node);
 }
 
-export function TemplateElement(node) {
+export function TemplateElement(node: Object) {
   this._push(node.value.raw);
 }
 
-export function TemplateLiteral(node) {
+export function TemplateLiteral(node: Object) {
   this.push("`");
 
   let quasis = node.quasis;

packages/babel-generator/src/generators/types.js

@@ -3,11 +3,11 @@
 
 import * as t from "babel-types";
 
-export function Identifier(node) {
+export function Identifier(node: Object) {
   this.push(node.name);
 }
 
-export function RestElement(node) {
+export function RestElement(node: Object) {
   this.push("...");
   this.print(node.argument, node);
 }
@@ -18,7 +18,7 @@ export {
   RestElement as RestProperty,
 };
 
-export function ObjectExpression(node) {
+export function ObjectExpression(node: Object) {
   let props = node.properties;
 
   this.push("{");
@@ -35,12 +35,12 @@ export function ObjectExpression(node) {
 
 export { ObjectExpression as ObjectPattern };
 
-export function ObjectMethod(node) {
+export function ObjectMethod(node: Object) {
   this.printJoin(node.decorators, node, { separator: "" });
   this._method(node);
 }
 
-export function ObjectProperty(node) {
+export function ObjectProperty(node: Object) {
   this.printJoin(node.decorators, node, { separator: "" });
 
   if (node.computed) {
@@ -70,7 +70,7 @@ export function ObjectProperty(node) {
   this.print(node.value, node);
 }
 
-export function ArrayExpression(node) {
+export function ArrayExpression(node: Object) {
   let elems = node.elements;
   let len   = elems.length;
 
@@ -98,11 +98,11 @@ export function ArrayExpression(node) {
 
 export { ArrayExpression as ArrayPattern };
 
-export function RegExpLiteral(node) {
+export function RegExpLiteral(node: Object) {
   this.push(`/${node.pattern}/${node.flags}`);
 }
 
-export function BooleanLiteral(node) {
+export function BooleanLiteral(node: Object) {
   this.push(node.value ? "true" : "false");
 }
 
@@ -110,15 +110,15 @@ export function NullLiteral() {
   this.push("null");
 }
 
-export function NumericLiteral(node) {
+export function NumericLiteral(node: Object) {
   this.push(node.value + "");
 }
 
-export function StringLiteral(node, parent) {
+export function StringLiteral(node: Object, parent: Object) {
   this.push(this._stringLiteral(node.value, parent));
 }
 
-export function _stringLiteral(val, parent) {
+export function _stringLiteral(val: string, parent: Object): string {
   val = JSON.stringify(val);
 
   // escape illegal js but valid json unicode characters

packages/babel-generator/src/index.js

@@ -34,6 +34,33 @@ export class CodeGenerator extends Printer {
     this.map        = new SourceMap(position, opts, code);
   }
 
+  format: {
+    shouldPrintComment: (comment: string) => boolean;
+    retainLines: boolean;
+    comments: boolean;
+    auxiliaryCommentBefore: string;
+    auxiliaryCommentAfter: string;
+    compact: boolean | "auto";
+    minified: boolean;
+    quotes: "single" | "double";
+    concise: boolean;
+    indent: {
+      adjustMultilineComment: boolean;
+      style: string;
+      base: number;
+    }
+  };
+
+  auxiliaryCommentBefore: string;
+  auxiliaryCommentAfter: string;
+  whitespace: Whitespace;
+  position: Position;
+  map: SourceMap;
+  comments: Array<Object>;
+  tokens: Array<Object>;
+  opts: Object;
+  ast: Object;
+
   /**
    * Normalize generator options, setting defaults.
    *
@@ -134,7 +161,7 @@ export class CodeGenerator extends Printer {
   }
 }
 
-export default function (ast, opts, code) {
+export default function (ast: Object, opts: Object, code: string): Object {
   let gen = new CodeGenerator(ast, opts, code);
   return gen.generate();
 }

packages/babel-generator/src/node/parentheses.js

@@ -1,4 +1,3 @@
-
 import * as t from "babel-types";
 
 const PRECEDENCE = {
@@ -28,13 +27,13 @@ const PRECEDENCE = {
   "**": 10
 };
 
-export function NullableTypeAnnotation(node, parent) {
+export function NullableTypeAnnotation(node: Object, parent: Object): boolean {
   return t.isArrayTypeAnnotation(parent);
 }
 
 export { NullableTypeAnnotation as FunctionTypeAnnotation };
 
-export function UpdateExpression(node, parent) {
+export function UpdateExpression(node: Object, parent: Object): boolean {
   if (t.isMemberExpression(parent) && parent.object === node) {
     // (foo++).test()
     return true;
@@ -43,7 +42,7 @@ export function UpdateExpression(node, parent) {
   return false;
 }
 
-export function ObjectExpression(node, parent, printStack) {
+export function ObjectExpression(node: Object, parent: Object, printStack: Array<Object>): boolean {
   if (t.isExpressionStatement(parent)) {
     // ({ foo: "bar" });
     return true;
@@ -52,7 +51,7 @@ export function ObjectExpression(node, parent, printStack) {
   return isFirstInStatement(printStack, true);
 }
 
-export function Binary(node, parent) {
+export function Binary(node: Object, parent: Object): boolean {
   if ((t.isCallExpression(parent) || t.isNewExpression(parent)) && parent.callee === node) {
     return true;
   }
@@ -85,7 +84,7 @@ export function Binary(node, parent) {
   return false;
 }
 
-export function BinaryExpression(node, parent) {
+export function BinaryExpression(node: Object, parent: Object): boolean {
   if (node.operator === "in") {
     // let i = (1 in []);
     if (t.isVariableDeclarator(parent)) {
@@ -101,7 +100,7 @@ export function BinaryExpression(node, parent) {
   return false;
 }
 
-export function SequenceExpression(node, parent) {
+export function SequenceExpression(node: Object, parent: Object): boolean {
   if (t.isForStatement(parent)) {
     // Although parentheses wouldn"t hurt around sequence
     // expressions in the head of for loops, traditional style
@@ -143,7 +142,7 @@ export function SequenceExpression(node, parent) {
   return true;
 }
 
-export function YieldExpression(node, parent) {
+export function YieldExpression(node: Object, parent: Object): boolean {
   return t.isBinary(parent) ||
          t.isUnaryLike(parent) ||
          t.isCallExpression(parent) ||
@@ -153,7 +152,7 @@ export function YieldExpression(node, parent) {
 
 export { YieldExpression as AwaitExpression };
 
-export function ClassExpression(node, parent) {
+export function ClassExpression(node: Object, parent: Object): boolean {
   // (class {});
   if (t.isExpressionStatement(parent)) {
     return true;
@@ -167,7 +166,7 @@ export function ClassExpression(node, parent) {
   return false;
 }
 
-export function UnaryLike(node, parent) {
+export function UnaryLike(node: Object, parent: Object): boolean {
   if (t.isMemberExpression(parent, { object: node })) {
     return true;
   }
@@ -179,7 +178,7 @@ export function UnaryLike(node, parent) {
   return false;
 }
 
-export function FunctionExpression(node, parent, printStack) {
+export function FunctionExpression(node: Object, parent: Object, printStack: Array<Object>): boolean {
   // (function () {});
   if (t.isExpressionStatement(parent)) {
     return true;
@@ -193,7 +192,7 @@ export function FunctionExpression(node, parent, printStack) {
   return isFirstInStatement(printStack);
 }
 
-export function ArrowFunctionExpression(node, parent) {
+export function ArrowFunctionExpression(node: Object, parent: Object): boolean {
   // export default (function () {});
   if (t.isExportDeclaration(parent)) {
     return true;
@@ -210,7 +209,7 @@ export function ArrowFunctionExpression(node, parent) {
   return UnaryLike(node, parent);
 }
 
-export function ConditionalExpression(node, parent) {
+export function ConditionalExpression(node: Object, parent: Object): boolean {
   if (t.isUnaryLike(parent)) {
     return true;
   }
@@ -226,7 +225,7 @@ export function ConditionalExpression(node, parent) {
   return UnaryLike(node, parent);
 }
 
-export function AssignmentExpression(node) {
+export function AssignmentExpression(node: Object): boolean {
   if (t.isObjectPattern(node.left)) {
     return true;
   } else {
@@ -236,7 +235,7 @@ export function AssignmentExpression(node) {
 
 // Walk up the print stack to deterimine if our node can come first
 // in statement.
-function isFirstInStatement(printStack, considerArrow = false) {
+function isFirstInStatement(printStack: Array<Object>, considerArrow: bool = false): boolean {
   let i = printStack.length - 1;
   let node = printStack[i];
   i--;

packages/babel-generator/src/node/whitespace.js

@@ -3,6 +3,11 @@ import each from "lodash/collection/each";
 import map from "lodash/collection/map";
 import * as t from "babel-types";
 
+type WhitespaceObject = {
+  before?: boolean,
+  after?: boolean
+};
+
 /**
  * Crawl a node to test if it contains a CallExpression, a Function, or a Helper.
  *
@@ -63,7 +68,7 @@ exports.nodes = {
    * Test if AssignmentExpression needs whitespace.
    */
 
-  AssignmentExpression(node) {
+  AssignmentExpression(node: Object): ?WhitespaceObject {
     let state = crawl(node.right);
     if ((state.hasCall && state.hasHelper) || state.hasFunction) {
       return {
@@ -77,7 +82,7 @@ exports.nodes = {
    * Test if SwitchCase needs whitespace.
    */
 
-  SwitchCase(node, parent) {
+  SwitchCase(node: Object, parent: Object): ?WhitespaceObject {
     return {
       before: node.consequent.length || parent.cases[0] === node
     };
@@ -87,7 +92,7 @@ exports.nodes = {
    * Test if LogicalExpression needs whitespace.
    */
 
-  LogicalExpression(node) {
+  LogicalExpression(node: Object): ?WhitespaceObject {
     if (t.isFunction(node.left) || t.isFunction(node.right)) {
       return {
         after: true
@@ -99,7 +104,7 @@ exports.nodes = {
    * Test if Literal needs whitespace.
    */
 
-  Literal(node) {
+  Literal(node: Object): ?WhitespaceObject {
     if (node.value === "use strict") {
       return {
         after: true
@@ -111,7 +116,7 @@ exports.nodes = {
    * Test if CallExpression needs whitespace.
    */
 
-  CallExpression(node) {
+  CallExpression(node: Object): ?WhitespaceObject {
     if (t.isFunction(node.callee) || isHelper(node)) {
       return {
         before: true,
@@ -124,7 +129,7 @@ exports.nodes = {
    * Test if VariableDeclaration needs whitespace.
    */
 
-  VariableDeclaration(node) {
+  VariableDeclaration(node: Object): ?WhitespaceObject {
     for (let i = 0; i < node.declarations.length; i++) {
       let declar = node.declarations[i];
 
@@ -147,7 +152,7 @@ exports.nodes = {
    * Test if IfStatement needs whitespace.
    */
 
-  IfStatement(node) {
+  IfStatement(node: Object): ?WhitespaceObject {
     if (t.isBlockStatement(node.consequent)) {
       return {
         before: true,
@@ -163,7 +168,7 @@ exports.nodes = {
 
 exports.nodes.ObjectProperty =
 exports.nodes.ObjectMethod =
-exports.nodes.SpreadProperty = function (node, parent) {
+exports.nodes.SpreadProperty = function (node: Object, parent): ?WhitespaceObject {
   if (parent.properties[0] === node) {
     return {
       before: true
@@ -181,7 +186,7 @@ exports.list = {
    * Return VariableDeclaration declarations init properties.
    */
 
-  VariableDeclaration(node) {
+  VariableDeclaration(node: Object): Array<Object> {
     return map(node.declarations, "init");
   },
 
@@ -189,7 +194,7 @@ exports.list = {
    * Return VariableDeclaration elements.
    */
 
-  ArrayExpression(node) {
+  ArrayExpression(node: Object): Array<Object> {
     return node.elements;
   },
 
@@ -197,7 +202,7 @@ exports.list = {
    * Return VariableDeclaration properties.
    */
 
-  ObjectExpression(node) {
+  ObjectExpression(node: Object): Array<Object> {
     return node.properties;
   }
 };

packages/babel-generator/src/position.js

@@ -1,9 +1,10 @@
-
 /**
  * Track current position in code generation.
  */
 
 export default class Position {
+  column: number;
+  line: number;
 
   constructor() {
     this.line = 1;
@@ -14,7 +15,7 @@ export default class Position {
    * Push a string to the current position, mantaining the current line and column.
    */
 
-  push(str) {
+  push(str: string): void {
     for (let i = 0; i < str.length; i++) {
       if (str[i] === "\n") {
         this.line++;
@@ -29,7 +30,7 @@ export default class Position {
    * Unshift a string from the current position, mantaining the current line and column.
    */
 
-  unshift(str) {
+  unshift(str: string): void {
     for (let i = 0; i < str.length; i++) {
       if (str[i] === "\n") {
         this.line--;

packages/babel-generator/src/printer.js

@@ -120,7 +120,7 @@ export default class Printer extends Buffer {
     printMethod.call(this, node, parent);
   }
 
-  printJoin(nodes, parent, opts = {}) {
+  printJoin(nodes: ?Array, parent: Object, opts = {}) {
     if (!nodes || !nodes.length) return;
 
     let len = nodes.length;
@@ -310,7 +310,7 @@ export default class Printer extends Buffer {
     this.newline(this.whitespace.getNewlinesAfter(comment));
   }
 
-  printComments(comments) {
+  printComments(comments?: Array<Object>) {
     if (!comments || !comments.length) return;
 
     for (let comment of comments) {

packages/babel-generator/src/whitespace.js

@@ -82,10 +82,10 @@ export default class Whitespace {
    * Find a token between start and end.
    */
 
-  _findToken(test, start, end) {
+  _findToken(test: Function, start: number, end: number): number {
     if (start >= end) return -1;
     const middle = (start + end) >>> 1;
-    const match = test(this.tokens[middle]);
+    const match: number = test(this.tokens[middle]);
     if (match < 0) {
       return this._findToken(test, middle + 1, end);
     } else if (match > 0) {

packages/babel-helper-bindify-decorators/src/index.js

@@ -1,6 +1,7 @@
+import type { NodePath } from "babel-traverse";
 import * as t from "babel-types";
 
-export default function bindifyDecorators(decorators) {
+export default function bindifyDecorators(decorators: Array<NodePath>): Array<NodePath> {
   for (let decoratorPath of decorators) {
     let decorator = decoratorPath.node;
     let expression = decorator.expression;

packages/babel-helper-builder-binary-assignment-operator-visitor/src/index.js

@@ -1,7 +1,10 @@
 import explode from "babel-helper-explode-assignable-expression";
 import * as t from "babel-types";
 
-export default function (opts) {
+export default function (opts: {
+  build: Function;
+  operator: string;
+}): Object {
   let visitor = {};
 
   function isAssignment(node) {

packages/babel-helper-builder-conditional-assignment-operator-visitor/src/index.js

@@ -1,7 +1,13 @@
 import explode from "babel-helper-explode-assignable-expression";
 import * as t from "babel-types";
 
-export default function (exports, opts) {
+export default function (
+  exports: Object,
+  opts: {
+    build: Function;
+    is: Function;
+  },
+) {
   let buildAssignment = function (left, right) {
     return t.assignmentExpression("=", left, right);
   };

packages/babel-helper-builder-react-jsx/src/index.js

@@ -1,6 +1,14 @@
 import esutils from "esutils";
 import * as t from "babel-types";
 
+type ElementState = {
+  tagExpr: Object; // tag node
+  tagName: string; // raw string tag name
+  args: Array<Object>; // array of call arguments
+  call?: Object; // optional call property that can be set to override the call expression returned
+  pre?: Function; // function called with (state: ElementState) before building attribs
+  post?: Function; // function called with (state: ElementState) after building attribs
+};
 
 export default function (opts) {
   let visitor = {};
@@ -81,7 +89,7 @@ export default function (opts) {
       tagName = tagExpr.value;
     }
 
-    let state = {
+    let state: ElementState = {
       tagExpr: tagExpr,
       tagName: tagName,
       args:    args

packages/babel-helper-call-delegate/src/index.js

@@ -1,4 +1,5 @@
 import hoistVariables from "babel-helper-hoist-variables";
+import type { NodePath } from "babel-traverse";
 import * as t from "babel-types";
 
 let visitor = {
@@ -17,7 +18,7 @@ let visitor = {
   }
 };
 
-export default function (path, scope = path.scope) {
+export default function (path: NodePath, scope = path.scope) {
   let { node } = path;
   let container = t.functionExpression(null, [], node.body, node.generator, node.async);
 

packages/babel-helper-define-map/src/index.js

@@ -5,7 +5,7 @@ import each from "lodash/collection/each";
 import has from "lodash/object/has";
 import * as t from "babel-types";
 
-function toKind(node) {
+function toKind(node: Object) {
   if (t.isClassMethod(node) || t.isObjectMethod(node)) {
     if (node.kind === "get" || node.kind === "set") {
       return node.kind;
@@ -15,7 +15,7 @@ function toKind(node) {
   return "value";
 }
 
-export function push(mutatorMap, node, kind, file, scope) {
+export function push(mutatorMap: Object, node: Object, kind: string, file, scope?): Object {
   let alias = t.toKeyAlias(node);
 
   //
@@ -75,7 +75,7 @@ export function push(mutatorMap, node, kind, file, scope) {
   return map;
 }
 
-export function hasComputed(mutatorMap) {
+export function hasComputed(mutatorMap: Object): boolean {
   for (let key in mutatorMap) {
     if (mutatorMap[key]._computed) {
       return true;
@@ -84,7 +84,7 @@ export function hasComputed(mutatorMap) {
   return false;
 }
 
-export function toComputedObjectFromClass(obj) {
+export function toComputedObjectFromClass(obj: Object): Object {
   let objExpr = t.arrayExpression([]);
 
   for (let i = 0; i < obj.properties.length; i++) {
@@ -97,7 +97,7 @@ export function toComputedObjectFromClass(obj) {
   return objExpr;
 }
 
-export function toClassObject(mutatorMap) {
+export function toClassObject(mutatorMap: Object): Object {
   let objExpr = t.objectExpression([]);
 
   each(mutatorMap, function (map) {
@@ -124,7 +124,7 @@ export function toClassObject(mutatorMap) {
   return objExpr;
 }
 
-export function toDefineObject(mutatorMap) {
+export function toDefineObject(mutatorMap: Object): Object {
   each(mutatorMap, function (map) {
     if (map.value) map.writable = t.booleanLiteral(true);
     map.configurable = t.booleanLiteral(true);

packages/babel-helper-explode-assignable-expression/src/index.js

@@ -1,3 +1,4 @@
+import type { Scope } from "babel-traverse";
 import * as t from "babel-types";
 
 function getObjRef(node, nodes, file, scope) {
@@ -45,7 +46,16 @@ function getPropRef(node, nodes, file, scope) {
   return temp;
 }
 
-export default function (node, nodes, file, scope, allowedSingleIdent) {
+export default function (
+  node: Object,
+  nodes: Array<Object>,
+  file,
+  scope: Scope,
+  allowedSingleIdent?: boolean,
+): {
+  uid: Object;
+  ref: Object;
+} {
   let obj;
   if (t.isIdentifier(node) && allowedSingleIdent) {
     obj = node;

packages/babel-helper-explode-class/src/index.js

@@ -1,4 +1,5 @@
 import bindifyDecorators from "babel-helper-bindify-decorators";
+import type { NodePath } from "babel-traverse";
 import * as t from "babel-types";
 
 export default function (classPath) {
@@ -14,7 +15,7 @@ export default function (classPath) {
     path.replaceWith(uid);
   }
 
-  function memoiseDecorators(paths) {
+  function memoiseDecorators(paths: Array<NodePath>) {
     if (!Array.isArray(paths) || !paths.length) return;
 
     // ensure correct evaluation order of decorators
@@ -31,7 +32,7 @@ export default function (classPath) {
   maybeMemoise(classPath.get("superClass"));
   memoiseDecorators(classPath.get("decorators"), true);
 
-  let methods = classPath.get("body.body");
+  let methods: Array<NodePath> = classPath.get("body.body");
   for (let methodPath of methods) {
     if (methodPath.is("computed")) {
       maybeMemoise(methodPath.get("key"));

packages/babel-helper-fixtures/src/index.js

@@ -10,13 +10,35 @@ function humanize(val, noext) {
   return val.replace(/-/g, " ");
 }
 
+type TestFile = {
+  loc: string;
+  code: string;
+  filename: string;
+};
+
+type Test = {
+  title: string;
+  disabled: boolean;
+  options: Object;
+  exec: TestFile;
+  actual: TestFile;
+  expected: TestFile;
+};
+
+type Suite = {
+  options: Object;
+  tests: Array<Test>;
+  title: string;
+  filename: string;
+};
+
 function assertDirectory(loc) {
   if (!fs.statSync(loc).isDirectory()) {
     throw new Error(`Expected ${loc} to be a directory.`);
   }
 }
 
-function shouldIgnore(name, blacklist) {
+function shouldIgnore(name, blacklist?: Array<string>) {
   if (blacklist && blacklist.indexOf(name) >= 0) {
     return true;
   }
@@ -27,7 +49,7 @@ function shouldIgnore(name, blacklist) {
   return name[0] === "." || ext === ".md" || base === "LICENSE" || base === "options";
 }
 
-export default function get(entryLoc) {
+export default function get(entryLoc): Array<Suite> {
   let suites = [];
 
   let rootOpts = {};
@@ -125,7 +147,7 @@ export default function get(entryLoc) {
   return suites;
 }
 
-export function multiple(entryLoc, ignore) {
+export function multiple(entryLoc, ignore?: Array<string>) {
   let categories = {};
 
   for (let name of fs.readdirSync(entryLoc)) {

packages/babel-helper-get-function-arity/src/index.js

@@ -1,7 +1,7 @@
 import * as t from "babel-types";
 
-export default function (node) {
-  let params = node.params;
+export default function (node): number {
+  let params: Array<Object> = node.params;
   for (let i = 0; i < params.length; i++) {
     let param = params[i];
     if (t.isAssignmentPattern(param) || t.isRestElement(param)) {

packages/babel-helper-hoist-variables/src/index.js

@@ -14,7 +14,7 @@ let visitor = {
 
     let nodes = [];
 
-    let declarations = path.get("declarations");
+    let declarations: Array<Object> = path.get("declarations");
     let firstId;
 
     for (let declar of declarations) {
@@ -40,6 +40,6 @@ let visitor = {
   }
 };
 
-export default function (path, emit, kind = "var") {
+export default function (path, emit: Function, kind: "var" | "let" = "var") {
   path.traverse(visitor, { kind, emit });
 }

packages/babel-helper-regex/src/index.js

@@ -1,13 +1,11 @@
-
-
 import pull from "lodash/array/pull";
 import * as t from "babel-types";
 
-export function is(node, flag) {
+export function is(node: Object, flag: string): boolean {
   return t.isRegExpLiteral(node) && node.flags.indexOf(flag) >= 0;
 }
 
-export function pullFlag(node, flag) {
+export function pullFlag(node: Object, flag: string) {
   let flags = node.flags.split("");
   if (node.flags.indexOf(flag) < 0) return;
   pull(flags, flag);

packages/babel-helper-remap-async-to-generator/src/index.js

@@ -1,4 +1,6 @@
+/* @noflow */
 
+import type { NodePath } from "babel-traverse";
 import nameFunction from "babel-helper-function-name";
 import template from "babel-template";
 import * as t from "babel-types";
@@ -33,7 +35,7 @@ let awaitVisitor = {
   }
 };
 
-function classOrObjectMethod(path, callId) {
+function classOrObjectMethod(path: NodePath, callId: Object) {
   let node = path.node;
   let body = node.body;
 
@@ -49,7 +51,7 @@ function classOrObjectMethod(path, callId) {
   ];
 }
 
-function plainFunction(path, callId) {
+function plainFunction(path: NodePath, callId: Object) {
   let node = path.node;
   let wrapper = buildWrapper;
 
@@ -116,7 +118,7 @@ function plainFunction(path, callId) {
   }
 }
 
-export default function (path, callId) {
+export default function (path: NodePath, callId: Object) {
   let node = path.node;
   if (node.generator) return;
 

packages/babel-helper-replace-supers/src/index.js

@@ -1,5 +1,6 @@
 /* eslint max-len: 0 */
 
+import type { NodePath, Scope } from "babel-traverse";
 import optimiseCall from "babel-helper-optimise-call-expression";
 import * as messages from "babel-messages";
 import * as t from "babel-types";
@@ -72,7 +73,7 @@ let visitor = {
 };
 
 export default class ReplaceSupers {
-  constructor(opts, inClass = false) {
+  constructor(opts: Object, inClass?: boolean = false) {
     this.forceSuperMemoisation = opts.forceSuperMemoisation;
     this.methodPath            = opts.methodPath;
     this.methodNode            = opts.methodNode;
@@ -90,6 +91,27 @@ export default class ReplaceSupers {
     this.thises     = [];
   }
 
+  forceSuperMemoisation: boolean;
+  methodPath: NodePath;
+  methodNode: Object;
+  superRef: Object;
+  isStatic: boolean;
+  hasSuper: boolean;
+  inClass: boolean;
+  isLoose: boolean;
+  scope: Scope;
+  file;
+  opts: {
+    forceSuperMemoisation: boolean;
+    getObjetRef: Function;
+    methodPath: NodePath;
+    methodNode: Object;
+    superRef: Object;
+    isStatic: boolean;
+    isLoose: boolean;
+    file: any;
+  };
+
   getObjectRef() {
     return this.opts.objectRef || this.opts.getObjectRef();
   }
@@ -103,7 +125,7 @@ export default class ReplaceSupers {
    *
    */
 
-  setSuperProperty(property, value, isComputed) {
+  setSuperProperty(property: Object, value: Object, isComputed: boolean): Object {
     return t.callExpression(
       this.file.addHelper("set"),
       [
@@ -129,7 +151,7 @@ export default class ReplaceSupers {
    *
    */
 
-  getSuperProperty(property, isComputed) {
+  getSuperProperty(property: Object, isComputed: boolean): Object {
     return t.callExpression(
       this.file.addHelper("get"),
       [
@@ -149,7 +171,7 @@ export default class ReplaceSupers {
     this.methodPath.traverse(visitor, this);
   }
 
-  getLooseSuperProperty(id, parent) {
+  getLooseSuperProperty(id: Object, parent: Object) {
     let methodNode = this.methodNode;
     let superRef   = this.superRef || t.identifier("Function");
 
@@ -165,7 +187,7 @@ export default class ReplaceSupers {
     }
   }
 
-  looseHandle(path) {
+  looseHandle(path: NodePath) {
     let node = path.node;
     if (path.isSuper()) {
       return this.getLooseSuperProperty(node, path.parent);
@@ -199,7 +221,7 @@ export default class ReplaceSupers {
     }
   }
 
-  specHandle(path) {
+  specHandle(path: NodePath) {
     let property;
     let computed;
     let args;

packages/babel-helper-transform-fixture-test-runner/src/index.js

@@ -111,7 +111,13 @@ function runExec(opts, execCode) {
   return fn.apply(null, Object.values(sandbox));
 }
 
-export default function (fixturesLoc, name, suiteOpts = {}, taskOpts = {}, dynamicOpts) {
+export default function (
+  fixturesLoc: string,
+  name: string,
+  suiteOpts = {},
+  taskOpts = {},
+  dynamicOpts?: Function,
+) {
   let suites = getFixtures(fixturesLoc);
 
   for (let testSuite of suites) {

packages/babel-messages/src/index.js

@@ -47,7 +47,7 @@ export const MESSAGES = {
  * Get a message with $0 placeholders replaced by arguments.
  */
 
-export function get(key, ...args) {
+export function get(key: string, ...args: Array<any>): string {
   let msg = MESSAGES[key];
   if (!msg) throw new ReferenceError(`Unknown message ${JSON.stringify(key)}`);
 
@@ -64,7 +64,7 @@ export function get(key, ...args) {
  * Stingify arguments to be used inside messages.
  */
 
-export function parseArgs(args) {
+export function parseArgs(args: Array<any>): Array<string> {
   return args.map(function (val) {
     if (val != null && val.inspect) {
       return val.inspect();

packages/babel-plugin-check-es2015-constants/src/index.js

@@ -6,11 +6,11 @@ export default function ({ messages }) {
           let binding = scope.bindings[name];
           if (binding.kind !== "const" && binding.kind !== "module") continue;
 
-          for (let violation of binding.constantViolations) {
+          for (let violation of (binding.constantViolations: Array)) {
             throw violation.buildCodeFrameError(messages.get("readOnly", name));
           }
         }
-      }
+      },
     }
   };
 }

packages/babel-plugin-transform-class-constructor-call/src/index.js

@@ -17,8 +17,8 @@ let buildWrapper = template(`
 export default function ({ types: t }) {
   let ALREADY_VISITED = Symbol();
 
-  function findConstructorCall(path) {
-    let methods = path.get("body.body");
+  function findConstructorCall(path): ?Object {
+    let methods: Array<Object> = path.get("body.body");
 
     for (let method of methods) {
       if (method.node.kind === "constructorCall") {

packages/babel-plugin-transform-decorators/src/index.js

@@ -54,13 +54,13 @@ export default function ({ types: t }) {
     if (path.isClass()) {
       if (path.node.decorators) return true;
 
-      for (let method of path.node.body.body) {
+      for (let method of (path.node.body.body: Array<Object>)) {
         if (method.decorators) {
           return true;
         }
       }
     } else if (path.isObjectExpression()) {
-      for (let prop of path.node.properties) {
+      for (let prop of (path.node.properties: Array<Object>)) {
         if (prop.decorators) {
           return true;
         }

packages/babel-plugin-transform-es2015-block-scoped-functions/src/index.js

@@ -1,6 +1,6 @@
 export default function ({ types: t }) {
   function statementList(key, path) {
-    let paths = path.get(key);
+    let paths: Array = path.get(key);
 
     for (let path of paths) {
       let func = path.node;

packages/babel-plugin-transform-es2015-block-scoping/src/index.js

@@ -1,5 +1,8 @@
 /* eslint max-len: 0 */
 
+import type NodePath from "babel-traverse";
+import type Scope from "babel-traverse";
+import type File from "../../../file";
 import traverse from "babel-traverse";
 import { visitor as tdzVisitor } from "./tdz";
 import * as t from "babel-types";
@@ -288,7 +291,7 @@ let loopVisitor = {
 };
 
 class BlockScoping {
-  constructor(loopPath, blockPath, parent, scope, file) {
+  constructor(loopPath?: NodePath, blockPath: NodePath, parent: Object, scope: Scope, file: File) {
     this.parent = parent;
     this.scope  = scope;
     this.file   = file;
@@ -472,7 +475,7 @@ class BlockScoping {
    * Push the closure to the body.
    */
 
-  buildClosure(ret, call) {
+  buildClosure(ret: { type: "Identifier" }, call: { type: "CallExpression" }) {
     let has = this.has;
     if (has.hasReturn || has.hasBreakContinue) {
       this.buildHas(ret, call);
@@ -570,7 +573,7 @@ class BlockScoping {
    * later on.
    */
 
-  checkLoop() {
+  checkLoop(): Object {
     let state = {
       hasBreakContinue: false,
       ignoreLabeless:   false,
@@ -602,7 +605,7 @@ class BlockScoping {
    * their declarations hoisted to before the closure wrapper.
    */
 
-  pushDeclar(node) {
+  pushDeclar(node: { type: "VariableDeclaration" }): Array<Object> {
     let declars = [];
     let names = t.getBindingIdentifiers(node);
     for (let name in names) {
@@ -624,7 +627,7 @@ class BlockScoping {
     return replace;
   }
 
-  buildHas(ret, call) {
+  buildHas(ret: { type: "Identifier" }, call: { type: "CallExpression" }) {
     let body = this.body;
 
     body.push(t.variableDeclaration("var", [

packages/babel-plugin-transform-es2015-classes/src/vanilla.js

@@ -1,5 +1,6 @@
 /* eslint max-len: 0 */
 
+import type { NodePath } from "babel-traverse";
 import { visitors } from "babel-traverse";
 import ReplaceSupers from "babel-helper-replace-supers";
 import optimiseCall from "babel-helper-optimise-call-expression";
@@ -60,7 +61,7 @@ let findThisesVisitor = visitors.merge([noMethodVisitor, {
 }]);
 
 export default class ClassTransformer {
-  constructor(path, file) {
+  constructor(path: NodePath, file) {
     this.parent = path.parent;
     this.scope  = path.scope;
     this.node   = path.node;
@@ -148,7 +149,7 @@ export default class ClassTransformer {
     return func;
   }
 
-  pushToMap(node, enumerable, kind = "value", scope) {
+  pushToMap(node, enumerable, kind = "value", scope?) {
     let mutatorMap;
     if (node.static) {
       this.hasStaticDescriptors = true;
@@ -175,7 +176,7 @@ export default class ClassTransformer {
   constructorMeMaybe() {
     let hasConstructor = false;
     let paths = this.path.get("body.body");
-    for (let path of paths) {
+    for (let path of (paths: Array)) {
       hasConstructor = path.equals("kind", "constructor");
       if (hasConstructor) break;
     }
@@ -216,7 +217,7 @@ export default class ClassTransformer {
   }
 
   pushBody() {
-    let classBodyPaths = this.path.get("body.body");
+    let classBodyPaths: Array<Object> = this.path.get("body.body");
 
     for (let path of classBodyPaths) {
       let node = path.node;
@@ -450,7 +451,7 @@ export default class ClassTransformer {
    * Push a method to its respective mutatorMap.
    */
 
-  pushMethod(node, path) {
+  pushMethod(node: { type: "ClassMethod" }, path?: NodePath) {
     let scope = path ? path.scope : this.scope;
 
     if (node.kind === "method") {
@@ -468,7 +469,7 @@ export default class ClassTransformer {
    * Replace the constructor body of our class.
    */
 
-  pushConstructor(replaceSupers, method, path) {
+  pushConstructor(replaceSupers, method: { type: "ClassMethod" }, path: NodePath) {
     this.bareSupers = replaceSupers.bareSupers;
     this.superReturns = replaceSupers.returns;
 

packages/babel-plugin-transform-es2015-computed-properties/src/index.js

@@ -89,7 +89,7 @@ export default function ({ types: t, template }) {
         exit(path, state) {
           let { node, parent, scope } = path;
           let hasComputed = false;
-          for (let prop of node.properties) {
+          for (let prop of (node.properties: Array<Object>)) {
             hasComputed = prop.computed === true;
             if (hasComputed) break;
           }

packages/babel-plugin-transform-es2015-destructuring/src/index.js

@@ -7,7 +7,7 @@ export default function ({ types: t }) {
    */
 
   function variableDeclarationHasPattern(node) {
-    for (let declar of node.declarations) {
+    for (let declar of (node.declarations: Array)) {
       if (t.isPattern(declar.id)) {
         return true;
       }
@@ -20,7 +20,7 @@ export default function ({ types: t }) {
    */
 
   function hasRest(pattern) {
-    for (let elem of pattern.elements) {
+    for (let elem of (pattern.elements: Array)) {
       if (t.isRestElement(elem)) {
         return true;
       }
@@ -210,7 +210,7 @@ export default function ({ types: t }) {
       if (pattern.elements.length > arr.elements.length) return;
       if (pattern.elements.length < arr.elements.length && !hasRest(pattern)) return false;
 
-      for (let elem of pattern.elements) {
+      for (let elem of (pattern.elements: Array)) {
         // deopt on holes
         if (!elem) return false;
 
@@ -218,7 +218,7 @@ export default function ({ types: t }) {
         if (t.isMemberExpression(elem)) return false;
       }
 
-      for (let elem of arr.elements) {
+      for (let elem of (arr.elements: Array)) {
         // deopt on spread elements
         if (t.isSpreadElement(elem)) return false;
       }

packages/babel-plugin-transform-es2015-modules-commonjs/src/index.js

@@ -159,7 +159,7 @@ export default function () {
           let hasExports = false;
           let hasImports = false;
 
-          let body = path.get("body");
+          let body: Array<Object> = path.get("body");
           let imports = Object.create(null);
           let exports = Object.create(null);
 

packages/babel-plugin-transform-es2015-modules-systemjs/src/index.js

@@ -92,7 +92,7 @@ export default function ({ types: t }) {
             );
           }
 
-          let body = path.get("body");
+          let body: Array<Object> = path.get("body");
 
           let canHoist = true;
           for (let path of body) {

packages/babel-plugin-transform-es2015-object-super/src/index.js

@@ -30,7 +30,7 @@ export default function ({ types: t }) {
           let objectRef;
           let getObjectRef = () => objectRef = objectRef || path.scope.generateUidIdentifier("obj");
 
-          let propPaths = path.get("properties");
+          let propPaths: Array = path.get("properties");
           for (let propPath of propPaths) {
             if (propPath.isObjectProperty()) propPath = propPath.get("value");
             Property(propPath, propPath.node, path.scope, getObjectRef, file);

packages/babel-plugin-transform-es2015-parameters/src/default.js

@@ -22,7 +22,7 @@ let buildCutOff = template(`
 `);
 
 function hasDefaults(node) {
-  for (let param of node.params) {
+  for (let param of (node.params: Array<Object>)) {
     if (!t.isIdentifier(param)) return true;
   }
   return false;

packages/babel-plugin-transform-es2015-parameters/src/destructuring.js

@@ -2,7 +2,7 @@ import * as t from "babel-types";
 
 export let visitor = {
   Function(path) {
-    let params = path.get("params");
+    let params: Array = path.get("params");
 
     // If there's a rest param, no need to loop through it. Also, we need to
     // hoist one more level to get `declar` at the right spot.

packages/babel-plugin-transform-es2015-parameters/src/index.js

@@ -1,3 +1,4 @@
+import type { NodePath } from "babel-traverse";
 import { visitors } from "babel-traverse";
 
 import * as destructuring from "./destructuring";
@@ -9,7 +10,7 @@ export default function () {
     visitor: visitors.merge([{
       ArrowFunctionExpression(path) {
         // default/rest visitors require access to `arguments`
-        let params = path.get("params");
+        let params: Array<NodePath> = path.get("params");
         for (let param of params) {
           if (param.isRestElement() || param.isAssignmentPattern()) {
             path.arrowFunctionToShadowed();

packages/babel-plugin-transform-es2015-parameters/src/rest.js

@@ -198,7 +198,7 @@ export let visitor = {
 
     // There are only "shorthand" references
     if (!state.deopted && !state.references.length) {
-      for (let {path, cause} of state.candidates) {
+      for (let {path, cause} of (state.candidates: Array)) {
         switch (cause) {
           case "indexGetter":
             optimiseIndexGetter(path, argsId, state.offset);

packages/babel-plugin-transform-es2015-spread/src/index.js

@@ -16,7 +16,7 @@ export default function ({ types: t }) {
     return false;
   }
 
-  function build(props, scope, state) {
+  function build(props: Array, scope, state) {
     let nodes = [];
 
     let _props = [];

packages/babel-plugin-transform-es2015-template-literals/src/index.js

@@ -17,7 +17,7 @@ export default function ({ types: t }) {
         let strings = [];
         let raw     = [];
 
-        for (let elem of quasi.quasis) {
+        for (let elem of (quasi.quasis: Array)) {
           strings.push(t.stringLiteral(elem.value.cooked));
           raw.push(t.stringLiteral(elem.value.raw));
         }
@@ -37,11 +37,11 @@ export default function ({ types: t }) {
       },
 
       TemplateLiteral(path, state) {
-        let nodes = [];
+        let nodes: Array<Object> = [];
 
         let expressions = path.get("expressions");
 
-        for (let elem of path.node.quasis) {
+        for (let elem of (path.node.quasis: Array)) {
           nodes.push(t.stringLiteral(elem.value.cooked));
 
           let expr = expressions.shift();

packages/babel-plugin-transform-es5-property-mutators/src/index.js

@@ -6,7 +6,7 @@ export default function ({ types: t }) {
       ObjectExpression(path, file) {
         let { node } = path;
         let hasAny = false;
-        for (let prop of node.properties) {
+        for (let prop of (node.properties: Array)) {
           if (prop.kind === "get" || prop.kind === "set") {
             hasAny = true;
             break;

packages/babel-plugin-transform-flow-strip-types/src/index.js

@@ -6,7 +6,7 @@ export default function ({ types: t }) {
 
     visitor: {
       Program(path, { file: { ast: { comments } } }) {
-        for (let comment of comments) {
+        for (let comment of (comments: Array<Object>)) {
           if (comment.value.indexOf(FLOW_DIRECTIVE) >= 0) {
             // remove flow directive
             comment.value = comment.value.replace(FLOW_DIRECTIVE, "");

packages/babel-plugin-transform-object-rest-spread/src/index.js

@@ -1,6 +1,6 @@
 export default function ({ types: t }) {
   function hasSpread(node) {
-    for (let prop of node.properties) {
+    for (let prop of (node.properties: Array<Object>)) {
       if (t.isSpreadProperty(prop)) {
         return true;
       }
@@ -24,7 +24,7 @@ export default function ({ types: t }) {
           props = [];
         }
 
-        for (let prop of path.node.properties) {
+        for (let prop of (path.node.properties: Array)) {
           if (t.isSpreadProperty(prop)) {
             push();
             args.push(prop.argument);

packages/babel-plugin-transform-proto-to-assign/src/index.js

@@ -45,7 +45,7 @@ export default function ({ types: t }) {
         let proto;
         let { node } = path;
 
-        for (let prop of node.properties) {
+        for (let prop of (node.properties: Array)) {
           if (isProtoKey(prop)) {
             proto = prop.value;
             pull(node.properties, prop);

packages/babel-plugin-transform-react-inline-elements/src/index.js

@@ -42,7 +42,7 @@ export default function ({ types: t }) {
         }
 
         // props
-        for (let attr of open.attributes) {
+        for (let attr of (open.attributes: Array<Object>)) {
           if (isJSXAttributeOfName(attr, "key")) {
             key = getAttributeValue(attr);
           } else {

packages/babel-plugin-transform-react-jsx/src/index.js

@@ -23,7 +23,7 @@ export default function ({ types: t }) {
     let { file } = state;
     let id = state.opts.pragma || "React.createElement";
 
-    for (let comment of file.ast.comments) {
+    for (let comment of (file.ast.comments: Array<Object>)) {
       let matches = JSX_ANNOTATION_REGEX.exec(comment.value);
       if (matches) {
         id = matches[1];

packages/babel-plugin-transform-strict-mode/src/index.js

@@ -8,7 +8,7 @@ export default function () {
         
         let { node } = path;
 
-        for (let directive of node.directives) {
+        for (let directive of (node.directives: Array<Object>)) {
           if (directive.value.value === "use strict") return;
         }
 

packages/babel-register/src/node.js

@@ -1,4 +1,3 @@
-
 import deepClone from "lodash/lang/cloneDeep";
 import sourceMapSupport from "source-map-support";
 import * as registerCache from "./cache";
@@ -128,7 +127,7 @@ function hookExtensions(_exts) {
 
 hookExtensions(util.canCompile.EXTENSIONS);
 
-export default function (opts = {}) {
+export default function (opts?: Object = {}) {
   if (opts.only != null) only = util.arrayify(opts.only, util.regexify);
   if (opts.ignore != null) ignore = util.arrayify(opts.ignore, util.regexify);
 

packages/babel-template/src/index.js

@@ -10,7 +10,7 @@ import * as t from "babel-types";
 let FROM_TEMPLATE = "_fromTemplate"; //Symbol(); // todo: probably wont get copied over
 let TEMPLATE_SKIP = Symbol();
 
-export default function (code, opts) {
+export default function (code: string, opts?: Object): Function {
   // since we lazy parse the template, we get the current stack so we have the
   // original stack to append if it errors when parsing
   let stack;
@@ -52,7 +52,7 @@ export default function (code, opts) {
   };
 }
 
-function useTemplate(ast, nodes) {
+function useTemplate(ast, nodes?: Array<Object>) {
   ast = cloneDeep(ast);
   let { program } = ast;
 

packages/babel-traverse/src/context.js

@@ -11,12 +11,18 @@ export default class TraversalContext {
     this.opts       = opts;
   }
 
+  parentPath: NodePath;
+  scope;
+  state;
+  opts;
+  queue: ?Array<NodePath> = null;
+
   /**
    * This method does a simple check to determine whether or not we really need to attempt
    * visit a node. This will prevent us from constructing a NodePath.
    */
 
-  shouldVisit(node) {
+  shouldVisit(node): boolean {
     let opts = this.opts;
     if (opts.enter || opts.exit) return true;
 
@@ -24,7 +30,7 @@ export default class TraversalContext {
     if (opts[node.type]) return true;
 
     // check if we're going to traverse into this node
-    let keys = t.VISITOR_KEYS[node.type];
+    let keys: ?Array<string> = t.VISITOR_KEYS[node.type];
     if (!keys || !keys.length) return false;
 
     // we need to traverse into this node so ensure that it has children to traverse into!
@@ -35,7 +41,7 @@ export default class TraversalContext {
     return false;
   }
 
-  create(node, obj, key, listKey) {
+  create(node, obj, key, listKey): NodePath {
     return NodePath.get({
       parentPath: this.parentPath,
       parent: node,
@@ -45,7 +51,7 @@ export default class TraversalContext {
     });
   }
 
-  maybeQueue(path, notPriority) {
+  maybeQueue(path, notPriority?: boolean) {
     if (this.trap) {
       throw new Error("Infinite cycle detected");
     }
@@ -76,7 +82,7 @@ export default class TraversalContext {
     return this.visitQueue(queue);
   }
 
-  visitSingle(node, key) {
+  visitSingle(node, key): boolean {
     if (this.shouldVisit(node[key])) {
       return this.visitQueue([
         this.create(node, node, key)
@@ -86,7 +92,7 @@ export default class TraversalContext {
     }
   }
 
-  visitQueue(queue) {
+  visitQueue(queue: Array<NodePath>) {
     // set queue
     this.queue = queue;
     this.priorityQueue = [];

packages/babel-traverse/src/index.js

@@ -11,7 +11,13 @@ export { default as Scope } from "./scope";
 export { default as Hub } from "./hub";
 export { visitors };
 
-export default function traverse(parent, opts, scope, state, parentPath) {
+export default function traverse(
+  parent: Object | Array<Object>,
+  opts?: Object,
+  scope?: Object,
+  state: Object,
+  parentPath: Object,
+) {
   if (!parent) return;
   if (!opts) opts = {};
 
@@ -55,8 +61,8 @@ traverse.cheap = function (node, enter) {
   }
 };
 
-traverse.node = function (node, opts, scope, state, parentPath, skipKeys) {
-  let keys = t.VISITOR_KEYS[node.type];
+traverse.node = function (node: Object, opts: Object, scope: Object, state: Object, parentPath: Object, skipKeys?) {
+  let keys: Array = t.VISITOR_KEYS[node.type];
   if (!keys) return;
 
   let context = new TraversalContext(scope, opts, state, parentPath);
@@ -66,7 +72,7 @@ traverse.node = function (node, opts, scope, state, parentPath, skipKeys) {
   }
 };
 
-const CLEAR_KEYS = t.COMMENT_KEYS.concat([
+const CLEAR_KEYS: Array = t.COMMENT_KEYS.concat([
   "tokens", "comments",
   "start", "end", "loc",
   "raw", "rawValue"
@@ -81,7 +87,7 @@ traverse.clearNode = function (node) {
     if (key[0] === "_" && node[key] != null) node[key] = undefined;
   }
 
-  let syms = Object.getOwnPropertySymbols(node);
+  let syms: Array<Symbol> = Object.getOwnPropertySymbols(node);
   for (let sym of syms) {
     node[sym] = null;
   }
@@ -99,7 +105,7 @@ function hasBlacklistedType(path, state) {
   }
 }
 
-traverse.hasType = function (tree, scope, type, blacklistTypes) {
+traverse.hasType = function (tree: Object, scope: Object, type: Object, blacklistTypes: Array<string>): boolean {
   // the node we're searching in is blacklisted
   if (includes(blacklistTypes, tree.type)) return false;
 

packages/babel-traverse/src/path/ancestry.js

@@ -1,6 +1,7 @@
 // This file contains that retrieve or validate anything related to the current paths ancestry.
 
 import * as t from "babel-types";
+import NodePath from "./index";
 
 /**
  * Call the provided `callback` with the `NodePath`s of all the parents.
@@ -56,12 +57,12 @@ export function getStatementParent() {
  * position and visiting key.
  */
 
-export function getEarliestCommonAncestorFrom(paths) {
+export function getEarliestCommonAncestorFrom(paths: Array<NodePath>): NodePath {
   return this.getDeepestCommonAncestorFrom(paths, function (deepest, i, ancestries) {
     let earliest;
     let keys = t.VISITOR_KEYS[deepest.type];
 
-    for (let ancestry of ancestries) {
+    for (let ancestry of (ancestries: Array)) {
       let path = ancestry[i + 1];
 
       // first path
@@ -98,7 +99,7 @@ export function getEarliestCommonAncestorFrom(paths) {
  * TODO: Possible optimisation target.
  */
 
-export function getDeepestCommonAncestorFrom(paths, filter) {
+export function getDeepestCommonAncestorFrom(paths: Array<NodePath>, filter?: Function): NodePath {
   if (!paths.length) {
     return this;
   }
@@ -136,7 +137,7 @@ export function getDeepestCommonAncestorFrom(paths, filter) {
   depthLoop: for (let i = 0; i < minDepth; i++) {
     let shouldMatch = first[i];
 
-    for (let ancestry of ancestries) {
+    for (let ancestry of (ancestries: Array)) {
       if (ancestry[i] !== shouldMatch) {
         // we've hit a snag
         break depthLoop;
@@ -177,7 +178,7 @@ export function getAncestry() {
 export function inType() {
   let path = this;
   while (path) {
-    for (let type of arguments) {
+    for (let type of (arguments: Array)) {
       if (path.node.type === type) return true;
     }
     path = path.parentPath;
@@ -190,7 +191,7 @@ export function inType() {
  * Check if we're inside a shadowed function.
  */
 
-export function inShadow(key) {
+export function inShadow(key?) {
   let path = this;
   do {
     if (path.isFunction()) {

packages/babel-traverse/src/path/comments.js

@@ -22,7 +22,7 @@ export function shareCommentsWithSiblings() {
   next.addComments("leading", trailing);
 }
 
-export function addComment(type, content, line) {
+export function addComment(type, content, line?) {
   this.addComments(type, [{
     type: line ? "CommentLine" : "CommentBlock",
     value: content
@@ -33,7 +33,7 @@ export function addComment(type, content, line) {
  * Give node `comments` of the specified `type`.
  */
 
-export function addComments(type, comments) {
+export function addComments(type: string, comments: Array) {
   if (!comments) return;
 
   let node = this.node;

packages/babel-traverse/src/path/context.js

@@ -2,7 +2,7 @@
 
 import traverse from "../index";
 
-export function call(key) {
+export function call(key): boolean {
   let opts = this.opts;
 
   this.debug(() => key);
@@ -18,7 +18,7 @@ export function call(key) {
   return false;
 }
 
-export function _call(fns) {
+export function _call(fns?: Array<Function>): boolean {
   if (!fns) return false;
 
   for (let fn of fns) {
@@ -39,12 +39,12 @@ export function _call(fns) {
   return false;
 }
 
-export function isBlacklisted() {
+export function isBlacklisted(): boolean {
   let blacklist = this.opts.blacklist;
   return blacklist && blacklist.indexOf(this.node.type) > -1;
 }
 
-export function visit() {
+export function visit(): boolean {
   if (!this.node) {
     return false;
   }

packages/babel-traverse/src/path/conversion.js

@@ -2,7 +2,7 @@
 
 import * as t from "babel-types";
 
-export function toComputedKey() {
+export function toComputedKey(): Object {
   let node = this.node;
 
   let key;

packages/babel-traverse/src/path/evaluation.js

@@ -1,6 +1,8 @@
 /* eslint indent: 0 */
 /* eslint max-len: 0 */
 
+import type NodePath from "./index";
+
 // This file contains Babels metainterpreter that can evaluate static code.
 
 /* eslint eqeqeq: 0 */
@@ -26,7 +28,7 @@ const INVALID_METHODS = ["random"];
  *
  */
 
-export function evaluateTruthy() {
+export function evaluateTruthy(): boolean {
   let res = this.evaluate();
   if (res.confident) return !!res.value;
 }
@@ -46,9 +48,9 @@ export function evaluateTruthy() {
  *
  */
 
-export function evaluate() {
+export function evaluate(): { confident: boolean; value: any } {
   let confident = true;
-  let deoptPath;
+  let deoptPath: ?NodePath;
 
   function deopt(path) {
     if (!confident) return;
@@ -88,7 +90,7 @@ export function evaluate() {
       let i = 0;
       let exprs = path.get("expressions");
 
-      for (let elem of node.quasis) {
+      for (let elem of (node.quasis: Array<Object>)) {
         // not confident, evaluated an expression we don't like
         if (!confident) break;
 
@@ -178,7 +180,7 @@ export function evaluate() {
 
     if (path.isArrayExpression()) {
       let arr = [];
-      let elems = path.get("elements");
+      let elems: Array<NodePath> = path.get("elements");
       for (let elem of elems) {
         elem = elem.evaluate();
 

packages/babel-traverse/src/path/family.js

@@ -1,9 +1,10 @@
 // This file contains methods responsible for dealing with/retrieving children or siblings.
 
+import type TraversalContext from "../index";
 import NodePath from "./index";
 import * as t from "babel-types";
 
-export function getStatementParent() {
+export function getStatementParent(): ?NodePath {
   let path = this;
 
   do {
@@ -29,7 +30,7 @@ export function getOpposite() {
   }
 }
 
-export function getCompletionRecords() {
+export function getCompletionRecords(): Array {
   let paths = [];
 
   let add = function (path) {
@@ -66,7 +67,7 @@ export function getSibling(key) {
   });
 }
 
-export function get(key, context) {
+export function get(key: string, context?: boolean | TraversalContext): NodePath {
   if (context === true) context = this.context;
   let parts = key.split(".");
   if (parts.length === 1) { // "foo"
@@ -76,7 +77,7 @@ export function get(key, context) {
   }
 }
 
-export function _getKey(key, context) {
+export function _getKey(key, context?) {
   let node      = this.node;
   let container = node[key];
 
@@ -103,7 +104,7 @@ export function _getKey(key, context) {
 
 export function _getPattern(parts, context) {
   let path = this;
-  for (let part of parts) {
+  for (let part of (parts: Array)) {
     if (part === ".") {
       path = path.parentPath;
     } else {
@@ -117,10 +118,10 @@ export function _getPattern(parts, context) {
   return path;
 }
 
-export function getBindingIdentifiers(duplicates) {
+export function getBindingIdentifiers(duplicates?) {
   return t.getBindingIdentifiers(this.node, duplicates);
 }
 
-export function getOuterBindingIdentifiers(duplicates) {
+export function getOuterBindingIdentifiers(duplicates?) {
   return t.getOuterBindingIdentifiers(this.node, duplicates);
 }

packages/babel-traverse/src/path/index.js

@@ -1,5 +1,7 @@
 /* eslint max-len: 0 */
 
+import type Hub from "../hub";
+import type TraversalContext from "../context";
 import * as virtualTypes from "./lib/virtual-types";
 import buildDebug from "debug";
 import { PATH_CACHE_KEY } from "./constants";
@@ -12,7 +14,7 @@ import * as t from "babel-types";
 let debug = buildDebug("babel");
 
 export default class NodePath {
-  constructor(hub, parent) {
+  constructor(hub: Hub, parent: Object) {
     this.parent = parent;
     this.hub = hub;
     this.contexts = [];
@@ -36,7 +38,29 @@ export default class NodePath {
     this.typeAnnotation = null;
   }
 
-  static get({ hub, parentPath, parent, container, listKey, key }) {
+  parent: Object;
+  hub: Hub;
+  contexts: Array<TraversalContext>;
+  data: Object;
+  shouldSkip: boolean;
+  shouldStop: boolean;
+  removed: boolean;
+  state: any;
+  opts: ?Object;
+  skipKeys: ?Object;
+  parentPath: ?NodePath;
+  context: TraversalContext;
+  container: ?Object | Array<Object>;
+  listKey: ?string;
+  inList: boolean;
+  parentKey: ?string;
+  key: ?string;
+  node: ?Object;
+  scope: Scope;
+  type: ?string;
+  typeAnnotation: ?Object;
+
+  static get({ hub, parentPath, parent, container, listKey, key }): NodePath {
     if (!hub && parentPath) {
       hub = parentPath.hub;
     }
@@ -78,7 +102,7 @@ export default class NodePath {
     return path;
   }
 
-  getScope(scope) {
+  getScope(scope: Scope) {
     let ourScope = scope;
 
     // we're entering a new scope so let's construct it!
@@ -89,25 +113,25 @@ export default class NodePath {
     return ourScope;
   }
 
-  setData(key, val) {
+  setData(key: string, val: any): any {
     return this.data[key] = val;
   }
 
-  getData(key, def) {
+  getData(key: string, def?: any): any {
     let val = this.data[key];
     if (!val && def) val = this.data[key] = def;
     return val;
   }
 
-  buildCodeFrameError(msg, Error = SyntaxError) {
+  buildCodeFrameError(msg: string, Error: typeof Error = SyntaxError): Error {
     return this.hub.file.buildCodeFrameError(this.node, msg, Error);
   }
 
-  traverse(visitor, state) {
+  traverse(visitor: Object, state?: any) {
     traverse(this.node, visitor, this.scope, state, this);
   }
 
-  mark(type, message) {
+  mark(type: string, message: string) {
     this.hub.file.metadata.marked.push({
       type,
       message,
@@ -115,12 +139,12 @@ export default class NodePath {
     });
   }
 
-  set(key, node) {
+  set(key: string, node: Object) {
     t.validate(this.node, key, node);
     this.node[key] = node;
   }
 
-  getPathLocation() {
+  getPathLocation(): string {
     let parts = [];
     let path = this;
     do {
@@ -131,7 +155,7 @@ export default class NodePath {
     return parts.join(".");
   }
 
-  debug(buildMessage) {
+  debug(buildMessage: Function) {
     if (!debug.enabled) return;
     debug(`${this.getPathLocation()} ${this.type}: ${buildMessage()}`);
   }
@@ -149,7 +173,7 @@ assign(NodePath.prototype, require("./modification"));
 assign(NodePath.prototype, require("./family"));
 assign(NodePath.prototype, require("./comments"));
 
-for (let type of t.TYPES) {
+for (let type of (t.TYPES: Array<string>)) {
   let typeKey = `is${type}`;
   NodePath.prototype[typeKey] = function (opts) {
     return t[typeKey](this.node, opts);

packages/babel-traverse/src/path/inference/index.js

@@ -1,3 +1,4 @@
+import type NodePath from "./index";
 import * as inferers from "./inferers";
 import * as t from "babel-types";
 
@@ -5,7 +6,7 @@ import * as t from "babel-types";
  * Infer the type of the current `NodePath`.
  */
 
-export function getTypeAnnotation() {
+export function getTypeAnnotation(): Object {
   if (this.typeAnnotation) return this.typeAnnotation;
 
   let type = this._getTypeAnnotation() || t.anyTypeAnnotation();
@@ -17,7 +18,7 @@ export function getTypeAnnotation() {
  * todo: split up this method
  */
 
-export function _getTypeAnnotation() {
+export function _getTypeAnnotation(): ?Object {
   let node = this.node;
 
   if (!node) {
@@ -57,11 +58,11 @@ export function _getTypeAnnotation() {
   }
 }
 
-export function isBaseType(baseName, soft) {
+export function isBaseType(baseName: string, soft?: boolean): boolean {
   return _isBaseType(baseName, this.getTypeAnnotation(), soft);
 }
 
-function _isBaseType(baseName, type, soft) {
+function _isBaseType(baseName: string, type?, soft?): boolean {
   if (baseName === "string") {
     return t.isStringTypeAnnotation(type);
   } else if (baseName === "number") {
@@ -83,12 +84,12 @@ function _isBaseType(baseName, type, soft) {
   }
 }
 
-export function couldBeBaseType(name) {
+export function couldBeBaseType(name: string): boolean {
   let type = this.getTypeAnnotation();
   if (t.isAnyTypeAnnotation(type)) return true;
 
   if (t.isUnionTypeAnnotation(type)) {
-    for (let type2 of type.types) {
+    for (let type2 of (type.types: Array<Object>)) {
       if (t.isAnyTypeAnnotation(type2) || _isBaseType(name, type2, true)) {
         return true;
       }
@@ -99,7 +100,7 @@ export function couldBeBaseType(name) {
   }
 }
 
-export function baseTypeStrictlyMatches(right) {
+export function baseTypeStrictlyMatches(right: NodePath) {
   let left = this.getTypeAnnotation();
   right = right.getTypeAnnotation();
 
@@ -108,7 +109,7 @@ export function baseTypeStrictlyMatches(right) {
   }
 }
 
-export function isGenericType(genericName) {
+export function isGenericType(genericName: string): boolean {
   let type = this.getTypeAnnotation();
   return t.isGenericTypeAnnotation(type) && t.isIdentifier(type.id, { name: genericName });
 }

packages/babel-traverse/src/path/inference/inferer-reference.js

@@ -1,6 +1,7 @@
+import type NodePath from "../index";
 import * as t from "babel-types";
 
-export default function (node) {
+export default function (node: Object) {
   if (!this.isReferenced()) return;
 
   // check if a binding exists of this value and if so then return a union type of all
@@ -75,7 +76,7 @@ function getTypeAnnotationBindingConstantViolations(path, name) {
     constantViolations = constantViolations.concat(functionConstantViolations);
 
     // push on inferred types of violated paths
-    for (let violation of constantViolations) {
+    for (let violation of (constantViolations: Array<NodePath>)) {
       types.push(violation.getTypeAnnotation());
     }
   }

packages/babel-traverse/src/path/introspection.js

@@ -1,5 +1,6 @@
 // This file contains methods responsible for introspecting the current path for certain values.
 
+import type NodePath from "./index";
 import includes from "lodash/collection/includes";
 import * as t from "babel-types";
 
@@ -10,7 +11,7 @@ import * as t from "babel-types";
  * parsed nodes of `React.createClass` and `React["createClass"]`.
  */
 
-export function matchesPattern(pattern, allowPartial) {
+export function matchesPattern(pattern: string, allowPartial?: boolean): boolean {
   // not a member expression
   if (!this.isMemberExpression()) return false;
 
@@ -66,7 +67,7 @@ export function matchesPattern(pattern, allowPartial) {
  * if the array has any items, otherwise we just check if it's falsy.
  */
 
-export function has(key) {
+export function has(key): boolean {
   let val = this.node && this.node[key];
   if (val && Array.isArray(val)) {
     return !!val.length;
@@ -93,7 +94,7 @@ export let is = has;
  * Opposite of `has`.
  */
 
-export function isnt(key) {
+export function isnt(key): boolean {
   return !this.has(key);
 }
 
@@ -101,7 +102,7 @@ export function isnt(key) {
  * Check whether the path node `key` strict equals `value`.
  */
 
-export function equals(key, value) {
+export function equals(key, value): boolean {
   return this.node[key] === value;
 }
 
@@ -110,7 +111,7 @@ export function equals(key, value) {
  * been removed yet we still internally know the type and need it to calculate node replacement.
  */
 
-export function isNodeType(type) {
+export function isNodeType(type: string): boolean {
   return t.isType(this.type, type);
 }
 
@@ -154,7 +155,7 @@ export function canSwapBetweenExpressionAndStatement(replacement) {
  * Check whether the current path references a completion record
  */
 
-export function isCompletionRecord(allowInsideFunction) {
+export function isCompletionRecord(allowInsideFunction?) {
   let path = this;
   let first = true;
 
@@ -319,7 +320,7 @@ export function _guessExecutionStatusRelativeToDifferentFunctions(targetFuncPare
   // no references!
   if (!binding.references) return "before";
 
-  let referencePaths = binding.referencePaths;
+  let referencePaths: Array<NodePath> = binding.referencePaths;
 
   // verify that all of the references are calls
   for (let path of referencePaths) {
@@ -357,7 +358,7 @@ export function resolve(dangerous, resolved) {
   return this._resolve(dangerous, resolved) || this;
 }
 
-export function _resolve(dangerous, resolved) {
+export function _resolve(dangerous?, resolved?): ?NodePath {
   // detect infinite recursion
   // todo: possibly have a max length on this just to be safe
   if (resolved && resolved.indexOf(this) >= 0) return;
@@ -403,7 +404,7 @@ export function _resolve(dangerous, resolved) {
 
     if (target.isObjectExpression()) {
       let props = target.get("properties");
-      for (let prop of props) {
+      for (let prop of (props: Array)) {
         if (!prop.isProperty()) continue;
 
         let key = prop.get("key");

packages/babel-traverse/src/path/removal.js

@@ -18,7 +18,7 @@ export function remove() {
 }
 
 export function _callRemovalHooks() {
-  for (let fn of hooks) {
+  for (let fn of (hooks: Array<Function>)) {
     if (fn(this, this.parentPath)) return true;
   }
 }

packages/babel-traverse/src/path/replacement.js

@@ -22,7 +22,7 @@ let hoistVariablesVisitor = {
 
     let exprs = [];
 
-    for (let declar of path.node.declarations) {
+    for (let declar of (path.node.declarations: Array<Object>)) {
       if (declar.init) {
         exprs.push(t.expressionStatement(
           t.assignmentExpression("=", declar.id, declar.init)
@@ -42,7 +42,7 @@ let hoistVariablesVisitor = {
  *  - Remove the current node.
  */
 
-export function replaceWithMultiple(nodes) {
+export function replaceWithMultiple(nodes: Array<Object>) {
   this.resync();
 
   nodes = this._verifyNodeList(nodes);
@@ -178,7 +178,7 @@ export function _replaceWith(node) {
  * extremely important to retain original semantics.
  */
 
-export function replaceExpressionWithStatements(nodes) {
+export function replaceExpressionWithStatements(nodes: Array<Object>) {
   this.resync();
 
   let toSequenceExpression = t.toSequenceExpression(nodes, this.scope);
@@ -206,7 +206,7 @@ export function replaceExpressionWithStatements(nodes) {
     this.traverse(hoistVariablesVisitor);
 
     // add implicit returns to all ending expression statements
-    let completionRecords = this.get("callee").getCompletionRecords();
+    let completionRecords: Array<NodePath> = this.get("callee").getCompletionRecords();
     for (let path of completionRecords) {
       if (!path.isExpressionStatement()) continue;
 
@@ -229,7 +229,7 @@ export function replaceExpressionWithStatements(nodes) {
   }
 }
 
-export function replaceInline(nodes) {
+export function replaceInline(nodes: Object | Array<Object>) {
   this.resync();
 
   if (Array.isArray(nodes)) {

packages/babel-traverse/src/scope/binding.js

@@ -1,3 +1,4 @@
+import type NodePath from "../path";
 
 /**
  * This class is responsible for a binding inside of a scope.
@@ -35,12 +36,24 @@ export default class Binding {
     }
   }
 
+
+  constantViolations: Array<NodePath>;
+  constant: boolean;
+
+  referencePaths: Array<NodePath>;
+  referenced: boolean;
+  references: number;
+
+  hasDeoptedValue: boolean;
+  hasValue: boolean;
+  value: any;
+
   deoptValue() {
     this.clearValue();
     this.hasDeoptedValue = true;
   }
 
-  setValue(value) {
+  setValue(value: any) {
     if (this.hasDeoptedValue) return;
     this.hasValue = true;
     this.value    = value;
@@ -56,7 +69,7 @@ export default class Binding {
    * Register a constant violation with the provided `path`.
    */
 
-  reassign(path) {
+  reassign(path: Object) {
     this.constant = false;
     this.constantViolations.push(path);
   }
@@ -65,7 +78,7 @@ export default class Binding {
    * Increment the amount of references to this binding.
    */
 
-  reference(path) {
+  reference(path: NodePath) {
     this.referenced = true;
     this.references++;
     this.referencePaths.push(path);

packages/babel-traverse/src/scope/index.js

@@ -3,6 +3,7 @@
 import includes from "lodash/collection/includes";
 import repeating from "repeating";
 import Renamer from "./lib/renamer";
+import type NodePath from "../path";
 import traverse from "../index";
 import defaults from "lodash/object/defaults";
 import * as messages from "babel-messages";
@@ -48,7 +49,7 @@ function matchesParent(scope, parentScope) {
 }
 
 function getCacheMultiple(node, parentScope, self, singleCache) {
-  let scopes = node[CACHE_MULTIPLE_KEY] = node[CACHE_MULTIPLE_KEY] || [];
+  let scopes: Array<Scope> = node[CACHE_MULTIPLE_KEY] = node[CACHE_MULTIPLE_KEY] || [];
 
   if (singleCache) {
     // we have a scope assocation miss so push it onto our scopes
@@ -68,7 +69,7 @@ function getCacheMultiple(node, parentScope, self, singleCache) {
 
 let collectorVisitor = {
   For(path) {
-    for (let key of t.FOR_INIT_KEYS) {
+    for (let key of (t.FOR_INIT_KEYS: Array)) {
       let declar = path.get(key);
       if (declar.isVar()) path.scope.getFunctionParent().registerBinding("var", declar);
     }
@@ -106,7 +107,7 @@ let collectorVisitor = {
         let binding = scope.getBinding(id.name);
         if (binding) binding.reference();
       } else if (t.isVariableDeclaration(declar)) {
-        for (let decl of declar.declarations) {
+        for (let decl of (declar.declarations: Array<Object>)) {
           let ids = t.getBindingIdentifiers(decl);
           for (let name in ids) {
             let binding = scope.getBinding(name);
@@ -152,7 +153,7 @@ let collectorVisitor = {
 
   Block(path) {
     let paths = path.get("body");
-    for (let bodyPath of paths) {
+    for (let bodyPath of (paths: Array)) {
       if (bodyPath.isFunctionDeclaration()) {
         path.scope.getBlockParent().registerDeclaration(bodyPath);
       }
@@ -169,7 +170,7 @@ export default class Scope {
    * within.
    */
 
-  constructor(path, parentScope) {
+  constructor(path: NodePath, parentScope?: Scope) {
     if (parentScope && parentScope.block === path.node) {
       return parentScope;
     }
@@ -207,7 +208,7 @@ export default class Scope {
    * Traverse node with current scope and path.
    */
 
-  traverse(node, opts, state) {
+  traverse(node: Object, opts: Object, state?) {
     traverse(node, opts, this, state, this.path);
   }
 
@@ -215,7 +216,7 @@ export default class Scope {
    * Generate a unique identifier and add it to the current scope.
    */
 
-  generateDeclaredUidIdentifier(name = "temp") {
+  generateDeclaredUidIdentifier(name: string = "temp") {
     let id = this.generateUidIdentifier(name);
     this.push({ id });
     return id;
@@ -225,7 +226,7 @@ export default class Scope {
    * Generate a unique identifier.
    */
 
-  generateUidIdentifier(name = "temp") {
+  generateUidIdentifier(name: string = "temp") {
     return t.identifier(this.generateUid(name));
   }
 
@@ -233,7 +234,7 @@ export default class Scope {
    * Generate a unique `_id1` binding.
    */
 
-  generateUid(name = "temp") {
+  generateUid(name: string = "temp") {
     name = t.toIdentifier(name).replace(/^_+/, "").replace(/[0-9]+$/g, "");
 
     let uid;
@@ -264,7 +265,7 @@ export default class Scope {
    * Generate a unique identifier based on a node.
    */
 
-  generateUidIdentifierBasedOnNode(parent, defaultName) {
+  generateUidIdentifierBasedOnNode(parent: Object, defaultName?: String):  Object {
     let node = parent;
 
     if (t.isAssignmentExpression(parent)) {
@@ -282,7 +283,7 @@ export default class Scope {
         if (node.source) {
           add(node.source);
         } else if (node.specifiers && node.specifiers.length) {
-          for (let specifier of node.specifiers) {
+          for (let specifier of (node.specifiers: Array)) {
             add(specifier);
           }
         } else if (node.declaration) {
@@ -300,7 +301,7 @@ export default class Scope {
       } else if (t.isCallExpression(node)) {
         add(node.callee);
       } else if (t.isObjectExpression(node) || t.isObjectPattern(node)) {
-        for (let prop of node.properties) {
+        for (let prop of (node.properties: Array)) {
           add(prop.key || prop.argument);
         }
       }
@@ -324,7 +325,7 @@ export default class Scope {
    *  - Bound identifiers
    */
 
-  isStatic(node) {
+  isStatic(node: Object): boolean {
     if (t.isThisExpression(node) || t.isSuper(node)) {
       return true;
     }
@@ -345,7 +346,7 @@ export default class Scope {
    * Possibly generate a memoised identifier if it is not static and has consequences.
    */
 
-  maybeGenerateMemoised(node, dontPush) {
+  maybeGenerateMemoised(node: Object, dontPush?: boolean): ?Object {
     if (this.isStatic(node)) {
       return null;
     } else {
@@ -355,7 +356,7 @@ export default class Scope {
     }
   }
 
-  checkBlockScopedCollisions(local, kind, name, id) {
+  checkBlockScopedCollisions(local, kind: string, name: string, id: Object) {
     // ignore parameters
     if (kind === "param") return;
 
@@ -375,7 +376,7 @@ export default class Scope {
     }
   }
 
-  rename(oldName, newName, block) {
+  rename(oldName: string, newName: string, block?) {
     let binding = this.getBinding(oldName);
     if (binding) {
       newName = newName || this.generateUidIdentifier(oldName).name;
@@ -409,7 +410,7 @@ export default class Scope {
     console.log(sep);
   }
 
-  toArray(node, i) {
+  toArray(node: Object, i?: number) {
     let file = this.hub.file;
 
     if (t.isIdentifier(node)) {
@@ -449,21 +450,21 @@ export default class Scope {
     return t.callExpression(file.addHelper(helperName), args);
   }
 
-  registerDeclaration(path) {
+  registerDeclaration(path: NodePath) {
     if (path.isLabeledStatement()) {
       this.registerBinding("label", path);
     } else if (path.isFunctionDeclaration()) {
       this.registerBinding("hoisted", path.get("id"), path);
     } else if (path.isVariableDeclaration()) {
       let declarations = path.get("declarations");
-      for (let declar of declarations) {
+      for (let declar of (declarations: Array)) {
         this.registerBinding(path.node.kind, declar);
       }
     } else if (path.isClassDeclaration()) {
       this.registerBinding("let", path);
     } else if (path.isImportDeclaration()) {
       let specifiers = path.get("specifiers");
-      for (let specifier of specifiers) {
+      for (let specifier of (specifiers: Array)) {
         this.registerBinding("module", specifier);
       }
     } else if (path.isExportDeclaration()) {
@@ -484,7 +485,7 @@ export default class Scope {
     }
   }
 
-  registerConstantViolation(path) {
+  registerConstantViolation(path: NodePath) {
     let ids = path.getBindingIdentifiers();
     for (let name in ids) {
       let binding = this.getBinding(name);
@@ -492,11 +493,11 @@ export default class Scope {
     }
   }
 
-  registerBinding(kind, path, bindingPath = path) {
+  registerBinding(kind: string, path: NodePath, bindingPath = path) {
     if (!kind) throw new ReferenceError("no `kind`");
 
     if (path.isVariableDeclaration()) {
-      let declarators = path.get("declarations");
+      let declarators: Array<NodePath> = path.get("declarations");
       for (let declar of declarators) {
         this.registerBinding(kind, declar);
       }
@@ -507,7 +508,7 @@ export default class Scope {
     let ids = path.getBindingIdentifiers(true);
 
     for (let name in ids) {
-      for (let id of ids[name]) {
+      for (let id of (ids[name]: Array<Object>)) {
         let local = this.getOwnBinding(name);
         if (local) {
           // same identifier so continue safely as we're likely trying to register it
@@ -530,11 +531,11 @@ export default class Scope {
     }
   }
 
-  addGlobal(node) {
+  addGlobal(node: Object) {
     this.globals[node.name] = node;
   }
 
-  hasUid(name) {
+  hasUid(name): boolean {
     let scope = this;
 
     do {
@@ -544,7 +545,7 @@ export default class Scope {
     return false;
   }
 
-  hasGlobal(name) {
+  hasGlobal(name: string): boolean {
     let scope = this;
 
     do {
@@ -554,7 +555,7 @@ export default class Scope {
     return false;
   }
 
-  hasReference(name) {
+  hasReference(name: string): boolean {
     let scope = this;
 
     do {
@@ -564,7 +565,7 @@ export default class Scope {
     return false;
   }
 
-  isPure(node, constantsOnly) {
+  isPure(node, constantsOnly?: boolean) {
     if (t.isIdentifier(node)) {
       let binding = this.getBinding(node.name);
       if (!binding) return false;
@@ -581,12 +582,12 @@ export default class Scope {
     } else if (t.isBinary(node)) {
       return this.isPure(node.left, constantsOnly) && this.isPure(node.right, constantsOnly);
     } else if (t.isArrayExpression(node)) {
-      for (let elem of node.elements) {
+      for (let elem of (node.elements: Array<Object>)) {
         if (!this.isPure(elem, constantsOnly)) return false;
       }
       return true;
     } else if (t.isObjectExpression(node)) {
-      for (let prop of node.properties) {
+      for (let prop of (node.properties: Array<Object>)) {
         if (!this.isPure(prop, constantsOnly)) return false;
       }
       return true;
@@ -655,7 +656,7 @@ export default class Scope {
     // ForStatement - left, init
 
     if (path.isLoop()) {
-      for (let key of t.FOR_INIT_KEYS) {
+      for (let key of (t.FOR_INIT_KEYS: Array<string>)) {
         let node = path.get(key);
         if (node.isBlockScoped()) this.registerBinding(node.node.kind, node);
       }
@@ -680,7 +681,7 @@ export default class Scope {
     // Function - params, rest
 
     if (path.isFunction()) {
-      let params = path.get("params");
+      let params: Array<NodePath> = path.get("params");
       for (let param of params) {
         this.registerBinding("param", param);
       }
@@ -739,7 +740,13 @@ export default class Scope {
     }
   }
 
-  push(opts) {
+  push(opts: {
+    id: Object;
+    init: ?Object;
+    unique: ?boolean;
+    _blockHoist: ?number;
+    kind: "var" | "let";
+  }) {
     let path = this.path;
 
     if (!path.isBlockStatement() && !path.isProgram()) {
@@ -824,7 +831,7 @@ export default class Scope {
    * Walks the scope tree and gathers **all** bindings.
    */
 
-  getAllBindings() {
+  getAllBindings(): Object {
     let ids = Object.create(null);
 
     let scope = this;
@@ -840,10 +847,10 @@ export default class Scope {
    * Walks the scope tree and gathers all declarations of `kind`.
    */
 
-  getAllBindingsOfKind() {
+  getAllBindingsOfKind(): Object {
     let ids = Object.create(null);
 
-    for (let kind of arguments) {
+    for (let kind of (arguments: Array)) {
       let scope = this;
       do {
         for (let name in scope.bindings) {
@@ -857,11 +864,11 @@ export default class Scope {
     return ids;
   }
 
-  bindingIdentifierEquals(name, node) {
+  bindingIdentifierEquals(name: string, node: Object): boolean {
     return this.getBindingIdentifier(name) === node;
   }
 
-  getBinding(name) {
+  getBinding(name: string) {
     let scope = this;
 
     do {
@@ -870,25 +877,25 @@ export default class Scope {
     } while (scope = scope.parent);
   }
 
-  getOwnBinding(name) {
+  getOwnBinding(name: string) {
     return this.bindings[name];
   }
 
-  getBindingIdentifier(name) {
+  getBindingIdentifier(name: string) {
     let info = this.getBinding(name);
     return info && info.identifier;
   }
 
-  getOwnBindingIdentifier(name) {
+  getOwnBindingIdentifier(name: string) {
     let binding = this.bindings[name];
     return binding && binding.identifier;
   }
 
-  hasOwnBinding(name) {
+  hasOwnBinding(name: string) {
     return !!this.getOwnBinding(name);
   }
 
-  hasBinding(name, noGlobals) {
+  hasBinding(name: string, noGlobals?) {
     if (!name) return false;
     if (this.hasOwnBinding(name)) return true;
     if (this.parentHasBinding(name, noGlobals)) return true;
@@ -898,7 +905,7 @@ export default class Scope {
     return false;
   }
 
-  parentHasBinding(name, noGlobals) {
+  parentHasBinding(name: string, noGlobals?) {
     return this.parent && this.parent.hasBinding(name, noGlobals);
   }
 
@@ -915,11 +922,11 @@ export default class Scope {
     }
   }
 
-  removeOwnBinding(name) {
+  removeOwnBinding(name: string) {
     delete this.bindings[name];
   }
 
-  removeBinding(name) {
+  removeBinding(name: string) {
     // clear literal binding
     let info = this.getBinding(name);
     if (info) {

packages/babel-traverse/src/visitors.js

@@ -27,7 +27,7 @@ export function explode(visitor) {
   for (let nodeType in visitor) {
     if (shouldIgnoreKey(nodeType)) continue;
 
-    let parts = nodeType.split("|");
+    let parts: Array<string> = nodeType.split("|");
     if (parts.length === 1) continue;
 
     let fns = visitor[nodeType];
@@ -52,7 +52,7 @@ export function explode(visitor) {
   ensureCallbackArrays(visitor);
 
   // add type wrappers
-  for (let nodeType of Object.keys(visitor)) {
+  for (let nodeType of (Object.keys(visitor): Array)) {
     if (shouldIgnoreKey(nodeType)) continue;
 
     let wrapper = virtualTypes[nodeType];
@@ -68,7 +68,7 @@ export function explode(visitor) {
     delete visitor[nodeType];
 
     if (wrapper.types) {
-      for (let type of wrapper.types) {
+      for (let type of (wrapper.types: Array<string>)) {
         // merge the visitor if necessary or just put it back in
         if (visitor[type]) {
           mergePair(visitor[type], fns);
@@ -87,7 +87,7 @@ export function explode(visitor) {
 
     let fns = visitor[nodeType];
 
-    let aliases = t.FLIPPED_ALIAS_KEYS[nodeType];
+    let aliases: ?Array<string> = t.FLIPPED_ALIAS_KEYS[nodeType];
 
     let deprecratedKey = t.DEPRECATED_KEYS[nodeType];
     if (deprecratedKey) {
@@ -162,7 +162,7 @@ function validateVisitorMethods(path, val) {
   }
 }
 
-export function merge(visitors, states = []) {
+export function merge(visitors: Array, states: Array = []) {
   let rootVisitor = {};
 
   for (let i = 0; i < visitors.length; i++) {

packages/babel-types/src/converters.js

@@ -3,9 +3,10 @@ import isNumber from "lodash/lang/isNumber";
 import isRegExp from "lodash/lang/isRegExp";
 import isString from "lodash/lang/isString";
 import traverse from "babel-traverse";
+import type { Scope } from "babel-traverse";
 import * as t from "./index";
 
-export function toComputedKey(node, key = node.key || node.property) {
+export function toComputedKey(node: Object, key: Object = node.key || node.property): Object {
   if (!node.computed) {
     if (t.isIdentifier(key)) key = t.stringLiteral(key.name);
   }
@@ -21,7 +22,7 @@ export function toComputedKey(node, key = node.key || node.property) {
  * Expression statements are just resolved to their expression.
  */
 
-export function toSequenceExpression(nodes, scope) {
+export function toSequenceExpression(nodes: Array<Object>, scope: Scope): ?Object {
   if (!nodes || !nodes.length) return;
 
   let declars = [];
@@ -40,7 +41,7 @@ export function toSequenceExpression(nodes, scope) {
     let ensureLastUndefined = false;
     let exprs   = [];
 
-    for (let node of nodes) {
+    for (let node of (nodes: Array)) {
       if (t.isExpression(node)) {
         exprs.push(node);
       } else if (t.isExpressionStatement(node)) {
@@ -48,7 +49,7 @@ export function toSequenceExpression(nodes, scope) {
       } else if (t.isVariableDeclaration(node)) {
         if (node.kind !== "var") return bailed = true; // bailed
 
-        for (let declar of node.declarations) {
+        for (let declar of (node.declarations: Array)) {
           let bindings = t.getBindingIdentifiers(declar);
           for (let key in bindings) {
             declars.push({
@@ -98,7 +99,7 @@ export function toSequenceExpression(nodes, scope) {
   }
 }
 
-export function toKeyAlias(node, key = node.key) {
+export function toKeyAlias(node: Object, key: Object = node.key): string {
   let alias;
 
   if (node.kind === "method") {
@@ -132,7 +133,7 @@ toKeyAlias.increment = function () {
   }
 };
 
-export function toIdentifier(name) {
+export function toIdentifier(name: string): string {
   name = name + "";
 
   // replace all non-valid identifiers with dashes
@@ -153,7 +154,7 @@ export function toIdentifier(name) {
   return name || "_";
 }
 
-export function toBindingIdentifierName(name) {
+export function toBindingIdentifierName(name: string): string {
   name = toIdentifier(name);
   if (name === "eval" || name === "arguments") name = "_" + name;
   return name;
@@ -164,7 +165,7 @@ export function toBindingIdentifierName(name) {
  * @returns {Object|Boolean}
  */
 
-export function toStatement(node, ignore) {
+export function toStatement(node: Object, ignore?: boolean) {
   if (t.isStatement(node)) {
     return node;
   }
@@ -199,7 +200,7 @@ export function toStatement(node, ignore) {
   return node;
 }
 
-export function toExpression(node) {
+export function toExpression(node: Object): Object {
   if (t.isExpressionStatement(node)) {
     node = node.expression;
   }
@@ -217,7 +218,7 @@ export function toExpression(node) {
   }
 }
 
-export function toBlock(node, parent) {
+export function toBlock(node: Object, parent: Object): Object {
   if (t.isBlockStatement(node)) {
     return node;
   }
@@ -241,7 +242,7 @@ export function toBlock(node, parent) {
   return t.blockStatement(node);
 }
 
-export function valueToNode(value) {
+export function valueToNode(value: any): Object {
   // undefined
   if (value === undefined) {
     return t.identifier("undefined");

packages/babel-types/src/definitions/experimental.js

@@ -1,4 +1,3 @@
-
 import defineType, { assertNodeType } from "./index";
 
 defineType("AwaitExpression", {

packages/babel-types/src/definitions/flow.js

@@ -1,4 +1,3 @@
-
 import defineType from "./index";
 
 defineType("AnyTypeAnnotation", {

packages/babel-types/src/definitions/index.js

@@ -18,7 +18,7 @@ function getType(val) {
   }
 }
 
-export function assertEach(callback) {
+export function assertEach(callback: Function): Function {
   function validator(node, key, val) {
     if (!Array.isArray(val)) return;
 
@@ -30,7 +30,7 @@ export function assertEach(callback) {
   return validator;
 }
 
-export function assertOneOf(...vals) {
+export function assertOneOf(...vals): Function {
   function validate(node, key, val) {
     if (vals.indexOf(val) < 0) {
       throw new TypeError(
@@ -44,7 +44,7 @@ export function assertOneOf(...vals) {
   return validate;
 }
 
-export function assertNodeType(...types) {
+export function assertNodeType(...types: Array<string>): Function {
   function validate(node, key, val) {
     let valid = false;
 
@@ -68,7 +68,7 @@ export function assertNodeType(...types) {
   return validate;
 }
 
-export function assertNodeOrValueType(...types) {
+export function assertNodeOrValueType(...types: Array<string>): Function {
   function validate(node, key, val) {
     let valid = false;
 
@@ -92,7 +92,7 @@ export function assertNodeOrValueType(...types) {
   return validate;
 }
 
-export function assertValueType(type) {
+export function assertValueType(type: string): Function {
   function validate(node, key, val) {
     let valid = getType(val) === type;
 
@@ -106,7 +106,7 @@ export function assertValueType(type) {
   return validate;
 }
 
-export function chain(...fns) {
+export function chain(...fns: Array<Function>): Function {
   function validate(...args) {
     for (let fn of fns) {
       fn(...args);
@@ -116,7 +116,16 @@ export function chain(...fns) {
   return validate;
 }
 
-export default function defineType(type, opts = {}) {
+export default function defineType(
+  type: string,
+  opts: {
+    fields?: Object;
+    visitor?: Array<string>;
+    aliases?: Array<string>;
+    builder?: Array<string>;
+    inherits?: string;
+  } = {},
+) {
   let inherits = (opts.inherits && store[opts.inherits]) || {};
 
   opts.fields  = opts.fields || inherits.fields || {};
@@ -129,7 +138,7 @@ export default function defineType(type, opts = {}) {
   }
 
   // ensure all field keys are represented in `fields`
-  for (let key of opts.visitor.concat(opts.builder)) {
+  for (let key of (opts.visitor.concat(opts.builder): Array<string>)) {
     opts.fields[key] = opts.fields[key] || {};
   }