How about separate emitted code to independent modules?

[acrazing]

Currently, compile es6/7 code to es5/3 will emit generated code to local file. For example, if we write a file as follow:

function p(): Promise<number> {
  return new Promise<number>((resolve) => {
    setTimeout(() => resolve(1), 1e3)
  })
}

async function next() {
  const value = await p()
  console.log('next value %s', value)
  const next = await p()
  return next
}

const ret = next()

console.log('return: %s', ret)

ret.then((value) => console.log('promise returned value: %s', value))

Set the target to es5, the compile result as follow:

var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
    return new (P || (P = Promise))(function (resolve, reject) {
        function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
        function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
        function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
        step((generator = generator.apply(thisArg, _arguments)).next());
    });
};
var __generator = (this && this.__generator) || function (thisArg, body) {
    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t;
    return { next: verb(0), "throw": verb(1), "return": verb(2) };
    function verb(n) { return function (v) { return step([n, v]); }; }
    function step(op) {
        if (f) throw new TypeError("Generator is already executing.");
        while (_) try {
            if (f = 1, y && (t = y[op[0] & 2 ? "return" : op[0] ? "throw" : "next"]) && !(t = t.call(y, op[1])).done) return t;
            if (y = 0, t) op = [0, t.value];
            switch (op[0]) {
                case 0: case 1: t = op; break;
                case 4: _.label++; return { value: op[1], done: false };
                case 5: _.label++; y = op[1]; op = [0]; continue;
                case 7: op = _.ops.pop(); _.trys.pop(); continue;
                default:
                    if (!(t = _.trys, t = t.length > 0 && t[t.length - 1]) && (op[0] === 6 || op[0] === 2)) { _ = 0; continue; }
                    if (op[0] === 3 && (!t || (op[1] > t[0] && op[1] < t[3]))) { _.label = op[1]; break; }
                    if (op[0] === 6 && _.label < t[1]) { _.label = t[1]; t = op; break; }
                    if (t && _.label < t[2]) { _.label = t[2]; _.ops.push(op); break; }
                    if (t[2]) _.ops.pop();
                    _.trys.pop(); continue;
            }
            op = body.call(thisArg, _);
        } catch (e) { op = [6, e]; y = 0; } finally { f = t = 0; }
        if (op[0] & 5) throw op[1]; return { value: op[0] ? op[1] : void 0, done: true };
    }
};
function p() {
    return new Promise(function (resolve) {
        setTimeout(function () { return resolve(1); }, 1e3);
    });
}
function next() {
    return __awaiter(this, void 0, void 0, function () {
        var value, next;
        return __generator(this, function (_a) {
            switch (_a.label) {
                case 0: return [4 /*yield*/, p()];
                case 1:
                    value = _a.sent();
                    console.log('next value %s', value);
                    return [4 /*yield*/, p()];
                case 2:
                    next = _a.sent();
                    return [2 /*return*/, next];
            }
        });
    });
}
var ret = next();
console.log('return: %s', ret);
ret.then(function (value) { return console.log('promise returned value: %s', value); });

The generated file is so large! If we use async/await in each project file, will emit a mass of useless code.

How about separate the emited functions to a separated module, and use require to load it?

For example:

var __awaiter = require('typescript/libs/awaiter');
var __generator = require('typescript/libs/generator');

function p() {
    return new Promise(function (resolve) {
        setTimeout(function () { return resolve(1); }, 1e3);
    });
}
function next() {
    return __awaiter(this, void 0, void 0, function () {
        var value, next;
        return __generator(this, function (_a) {
            switch (_a.label) {
                case 0: return [4 /*yield*/, p()];
                case 1:
                    value = _a.sent();
                    console.log('next value %s', value);
                    return [4 /*yield*/, p()];
                case 2:
                    next = _a.sent();
                    return [2 /*return*/, next];
            }
        });
    });
}
var ret = next();
console.log('return: %s', ret);
ret.then(function (value) { return console.log('promise returned value: %s', value); });

[HerringtonDarkholme]

https://github.com/Microsoft/TypeScript/wiki/What%27s-new-in-TypeScript#support-for-external-helpers-library-tslib

[acrazing]

Thanks~