深入浅出Jscex

Jscex- 2011.10

• / / Jeffrey Zhao /•• http://blog.zhaojie.me/• @• F#, JavaScript, Scala, C#, Python, .NET, Mono...• Java

Jscex• JavaScript Computation EXpression• JavaScript• F# JavaScript • “ ” • JavaScript JavaScript

Jscex• • Jscex JavaScript• • Jscex /• JavaScript / • ECMAScript 3

• • •• • •

Jscex//var somethingAsync = eval(Jscex.compile("async", function (...) { // }));

function () { var res = $await(<async work>);}

function () { var res = $await(<async work>);} HTTP UI Web Service

var f = eval(Jscex.compile("async", function () { var img = $await(readAsync("http://...")); console.log("loaded!"); $await(writeAsync("./files/...")); console.log("saved!");}));

…var f = eval((function () { var _b_ = Jscex.builders["async"]; return _b_.Start(this, _b_.Delay(function () { _b_.Bind(readAsync(...), function (img) { console.log("loaded!"); return _b_.Bind(writeAsync(...), function () { console.log("saved!"); return _b_.Normal(); }); }); }) );}));

…var f = (function () { var _b_ = Jscex.builders["async"]; return _b_.Start(this, _b_.Delay(function () { _b_.Bind(readAsync(...), function (img) { console.log("loaded!"); return _b_.Bind(writeAsync(...), function () { console.log("saved!"); return _b_.Normal(); }); }); }) );});

Expressvar app = express.createServer();app.get(/, function (req, res) { /** * * * 1. * 2. * * 3. res * * “ ” **/});app.listen(3000);

Jscexapp.getAsync(/, eval(Jscex.compile("async", function (req, res) { var keys = $await(db.getKeysAsync(...)); var results = []; for (var i = 0; i < keys.length; i++) { var r = $await(cache.getAsync(keys[i])); if (!r) { r = $await(db.getItemAsync(keys[i])); } results.push(r); } res.send(generateList(results));})));

I/O• I/O • Web ••• I/O •

• • • $await(Jscex.Async.parallel(taskA, taskB)) • $await(taskA.continueWith(taskB))• $await • •• • taskA.start(); $await(taskB); $await(taskA);

//var i = 1;conn.onAsync("data", eval(Jscex.compile("async", function () { var id = i++; $await(step1); console.log("step 1 - request " + id); $await(step2); console.log("step 2 - request " + id); /** * * step 1 - request 1 * step 1 - request 2 * step 2 - request 2 * step 2 - request 1 **/})));

... the principle we go by is, dont expect to seea particular concurrency model put into C#because therere many different concurrencymodel ... its more about ﬁnding things arecommon to all kinds of concurrency ... - Anders Hejlsberg

Erlangvar i = 0;var agent = Agent.start(eval(Jscex.compile("async", function (mailbox) { while (true) { var id = i++; var msg = $await(mailbox.receive()); $await(step1); console.log("step 1 - request " + id); $await(step2); console.log("step 2 - request " + id); }})));conn.on("data", function (data) { // mailbox agent.send(data);});

Jscex• JavaScript • • •• “ ”

• JavaScript • while / for / for...in / do • if / switch • try...catch...ﬁnally • return / break / continue / throw• • with • break continue • switch break•

//var somethingAsync = eval(Jscex.compile("async", function (...) { // }));

evalSample = { // compile: function (func) { return "(" + func.toString() + ")"; }, // eval compileEx: function (func) { return eval("(" + func.toString() + ")"); }}

eval(function () { var a = 1; // f1 var f1 = eval(Sample.compile(function () { alert(a); })); f1(); // “1” // f2 Sample.compileEx var f2 = Sample.compileEx(function () { alert(a); }); f2(); // “a ”})();

• JavaScript• “bind” $await • • “ ” • “ ”

• JavaScript•• • JIT • JavaScript

“ ”MyClass.prototype = { get: function (n) { ... }, calculateAsync: eval(Jscex.compile("async", function (n) { var numbers = []; for (var i = 0; i < n; i++) numbers.push(i); this.result = $await(make(numbers)); }))}

“ ”MyClass.prototype = { get: function (n) { ... }, Jscex calculateAsync: eval(Jscex.compile("async", function (n) { var numbers = []; for (var i = 0; i < n; i++) numbers.push(i); this.result = $await(make(numbers)); }))} Jscex

Jscex vs.•• • Virtual Panel: How to Survive Asynchronous Programming in JavaScript• • StratiﬁedJS • Narrative JavaScript • Streamline Jscex

Jscex vs.• • • •• Jscex • JavaScript • •

Jscex vs.• • • •• Jscex • JavaScript • JavaScript • JavaScript

Streamline• Jscex • JavaScript • JIT •• Jscex • • Yield – Resume vs. Asynchronous Callbacks – An Equivalence

Streamline (input)var bubbleSortAsync = function (array, _) { for (var x = 0; x < array.length; x++) { for (var y = 0; y < array.length - x; y++) { if (compareAsync(array[y], array[y + 1], _) > 0) swapAsync(array, y, y + 1, _); } }}

Streamline (compiled)var bubbleSortAsync = function __1(array, _) { if (!_) { return __future(__1, arguments, 1); } if ((y < (array.length - x))) {; return compareAsync(array[y], array[(y + 1)], __cb(_, function(__0, r) { var __then = _; if ((r > 0)) { var x = 0; return swapAsync(array, y, (y + 1), __cb(_, __then)); var __4 = false; } return function(__break) { ; var __loop = __nt(_, function() { return __then(); var __then = __loop; })); if (__4) { } x++; else { } return __break(); else { } __4 = true; ; } }); ; return __loop(); if ((x < array.length)) { }(__then); var y = 0; } var __3 = false; else { return function(__break) { return __break(); var __loop = __nt(_, function() { } var __then = __loop; ; if (__3) { }); y++; return __loop(); } }(__then); else { }; __3 = true; } ; http://sage.github.com/streamlinejs/examples/streamlineMe.html

Jecex (input)var bubbleSortAsync = eval(Jscex.compile("async", function (array) { for (var x = 0; x < array.length; x++) { for (var y = 0; y < array.length - x; y++) { var r = $await(compareAsync(array[y], array[y + 1])); if (r > 0) $await(swapAsync(array, y, y + 1)); } }}));

Jecex (compiled)var bubbleSortAsync = (function (array) { var _b_ = Jscex.builders["async"]; return _b_.Start(this, _b_.Delay(function () { var x = 0; return _b_.Loop( function () { return x < array.length; }, function () { x++; }, _b_.Delay(function () { var y = 0; return _b_.Loop( function () { return y < (array.length - x); }, function () { y++; } _b_.Delay(function () { return _b_.Bind(compareAsync(array[y], array[y + 1]), function (r) { if (r > 0) { return _b_.Bind(swapAsync(array, y, y + 1), function () { return _b_.Normal(); }); } else { return _b_.Normal(); } }); }), false ); }), false ); }) );})

Jecex (compiled) var bubbleSortAsync = (function (array) { var _b_ = Jscex.builders["async"]; return _b_.Start(this, _b_.Delay(function () { outer loop var x = 0; return _b_.Loop( function () { return x < array.length; }, function () { x++; }, _b_.Delay(function () { var y = 0; return _b_.Loop( inner loop function () { return y < (array.length - x); }, function () { y++; } _b_.Delay(function () { return _b_.Bind(compareAsync(array[y], array[y + 1]), function (r) { if (r > 0) { return _b_.Bind(swapAsync(array, y, y + 1), function () {$await(compareAsync(...)) return _b_.Normal(); }); } else { $await(swapAsync(...)) return _b_.Normal(); } }); }), false ); }), false ); }) ); })

Jscex• • • “debugger”• JavaScript • Start, Delay, Combine • Loop, Try • Normal, Return, Break, Continue, Throw • Bind

Node.js

• • JIT • AOT• • • Python C# JavaScript 1.7 • …

AOT// AOTAgent.start(eval(Jscex.compile("async", function (mailbox) { ...})));// AOT//// gzip 3kbAgent.start((function (mailbox) { var _b_ = Jscex.builders["async"]; return _b_.Start(this, ... );}));

Jscex• • “ ”•

//var fib = eval(Jscex.compile("seq", function () { var i = 0, j = 1; while (true) { $yield(i); // the bind operation var t = i; i = j; j += t; }}));var iter = fib().skip(10).take(10);while (iter.moveNext()) { console.log(iter.current);}

… Maybe Monadvar maybeFunc = function () { var maybeA = getA(); if (maybeA == Maybe.None) return Maybe.None; var maybeB = getB(); if (maybeB == Maybe.None) return Maybe.None; return maybeA.value + maybeB.value;}//var maybeFunc = eval(Jscex.compile("maybe", function () { var a = $try(getA()); var b = $try(getB()); return a + b;}));

• “ ” “ ” • •• • Jscex /

for Loopfunction (urls) { for (var i = 0; i < urls.length; i++) { $await(requestAsync(urls[i])); }}

for Loopfunction (urls) { for (var i = 0; i < urls.length; i++) { $await(requestAsync(urls[i])); }} function (urls) { var _b_ = Jscex.builders["async"]; return _b_.Start(this, _b_.Delay(function () { var i = 0; return _b_.Loop( function () { return i < urls.length; }, function () { i++; }, _b_.Delay(function () { return _b_.Bind(requestAsync(urls[i]), function () { return _b_.Normal(); }); }), false ); }) ); }

forfunction (urls) { var requests = []; for (var i = 0; i < urls.length; i++) { requests.push(requestAsync(urls[i])); } $await(Jscex.Async.parallel(requests));}

forfunction (urls) { var requests = []; for (var i = 0; i < urls.length; i++) { requests.push(requestAsync(urls[i])); } function (urls) { var _b_ = Jscex.builders["async"]; $await(Jscex.Async.parallel(requests));} return _b_.Start(this, _b_.Delay(function () { var requests = []; for (var i = 0; i < urls.length; i++) { requests.push(requestAsync(urls[i])); } return _b_.Bind(Jscex.Async.parallel(requests), function () { return _b_.Normal(); }); }) ); }

• BSD• • https://github.com/JeffreyZhao/jscex • http://www.sndacode.com/projects/jscex

深入浅出Jscex

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