c-spencer/yield.html

## yield.html
<!DOCTYPE html>
<html>
  <head>
    <title>Yield is Fun</title>
  </head>
  <script type="application/javascript;version=1.7">

    function __genLoop(generator, callback, onend) {
      if (callback && typeof callback === 'function') {
        try {
          callback(function () {
            var args = Array.prototype.slice.call(arguments);
            try {
              __genLoop(generator, generator.send(args), onend);
            } catch (err if err instanceof StopIteration) {
              onend();
            }
          });
        } catch (exc) {
          try {
            __genLoop(generator, generator.throw(exc), onend);
          } catch (err if err instanceof StopIteration) {
            onend();
          }
        }
      } else {
        generator.close();
        onend(callback);
      }
    }

    function __gen(generator) {
      return function () {
        var args = Array.prototype.slice.call(arguments);
        var callback = args[args.length - 1];
        var passed;
        if (typeof callback != "function") {
          passed = args;
          callback = function(){};
        } else {
          passed = args.slice(0, args.length - 1);
        }

        var gen = generator.apply({}, passed);

        __genLoop(gen, gen.next(), callback);
      }
    }

    var fnGen = __gen(function (d) {
      var a = 10, b, c;

      console.log("Yielding callback 1, with", d);
      [a] = yield function (callback) {
        setTimeout(function () {
          callback(20);
        }, 500);
      };

      console.log("Yielding callback 2, with", d);
      [b, c] = yield function (callback) {
        setTimeout(function () {
          callback(1, 15);
        }, 500);
      };

      console.log("a, b, c, d", a, b, c, d);
    });

    function make_async_work(str) {
      return function (callback) {
        setTimeout(function () {
          callback(str);
        }, 500);
      };
    }

    function fail_work(str) {
      return function (callback) {
        throw "failure!";
      }
    }

    function inside_function() {
      var a, b;
      try {
        [a] = yield make_async_work('inside 1');
      } catch (exc) {
        console.log("Caught Exception", exc);
        a = 'thank';
      }

      try {
        [b] = yield fail_work('inside 2');
      } catch (exc) {
        console.log("Caught Exception", exc);
        b = 'goodness';
      }

      console.log("Yielding return", a + b + 'return value');

      yield a + b + 'return value';
    }

    function outside_function() {
      [b] = yield function (callback) {
        setTimeout(function () {
          __gen(inside_function)(function (result) {
            console.log("Result inside b.", result);
            callback(result);
          });
        }, 500)
      }
      console.log("Yielded b");

      yield b;
    }

    __gen(outside_function)(function (result) {
      console.log(result + ' outside value');
    });

    fnGen(17, function (result) {
      console.log("Finished!", result);
    });

    fnGen(27);
  </script>

  <script type="application/coffeescript-fork">

    serverRequest = (args..., callback) ->
      setTimeout ->
        callback.apply({}, i + 10 for i in args)
      , 500

    # fnGen is an asynchronously called function with an implicit final
    # completion callback after the defined arguments.

    # the ~> defines a generatorLoop wrapped function which uses the generator
    # to sychronise by doing async processing in a yield -> evaluate -> send loop.

    # <~ defines a blocking call to a asynchronous function, with a completion
    # callback passed as a final parameter if a function or function call, otherwise
    # followed by a named completion callback.

    fnGen = (d) ~>

      # Implicit completion callback with other arguments
      [a] <~ serverRequest 20

      # Named explicit completion callback
      [b, c] <~ finish
        doServerRequest 10, (n) ->
          finish n, n - 15

      # Implicit completion callback with no arguments
      [e] <~ serverRequest

      console.log a, b, c, d, e
      # a = 20 + 10
      # b = 10 + 10
      # c = 10 + 10 - 15
      # d = d
      # e = undefined

      # Nesting
      [f] <~ finish
        nested = ~>
          [a] <~ serverRequest 60
          [b] <~ serverRequest 40

          a + b

        nested (c) ->
          finish c

      # Nesting silly.
      [f] <~ ~>
        [a] <~ serverRequest 60
        [b] <~ serverRequest 40

        a + b

      console.log f
      # f = 120

      # implicit return yield
      [a, b, c]

    fnGen 5, (results) ->
      console.log(results); # [30, 20, 5]
      console.log "Finished!"
  </script>
</html>
	<!DOCTYPE html>
	<html>
	<head>
	<title>Yield is Fun</title>
	</head>
	<script type="application/javascript;version=1.7">

	function __genLoop(generator, callback, onend) {
	if (callback && typeof callback === 'function') {
	try {
	callback(function () {
	var args = Array.prototype.slice.call(arguments);
	try {
	__genLoop(generator, generator.send(args), onend);
	} catch (err if err instanceof StopIteration) {
	onend();
	}
	});
	} catch (exc) {
	try {
	__genLoop(generator, generator.throw(exc), onend);
	} catch (err if err instanceof StopIteration) {
	onend();
	}
	}
	} else {
	generator.close();
	onend(callback);
	}
	}

	function __gen(generator) {
	return function () {
	var args = Array.prototype.slice.call(arguments);
	var callback = args[args.length - 1];
	var passed;
	if (typeof callback != "function") {
	passed = args;
	callback = function(){};
	} else {
	passed = args.slice(0, args.length - 1);
	}

	var gen = generator.apply({}, passed);

	__genLoop(gen, gen.next(), callback);
	}
	}

	var fnGen = __gen(function (d) {
	var a = 10, b, c;

	console.log("Yielding callback 1, with", d);
	[a] = yield function (callback) {
	setTimeout(function () {
	callback(20);
	}, 500);
	};

	console.log("Yielding callback 2, with", d);
	[b, c] = yield function (callback) {
	setTimeout(function () {
	callback(1, 15);
	}, 500);
	};

	console.log("a, b, c, d", a, b, c, d);
	});

	function make_async_work(str) {
	return function (callback) {
	setTimeout(function () {
	callback(str);
	}, 500);
	};
	}

	function fail_work(str) {
	return function (callback) {
	throw "failure!";
	}
	}

	function inside_function() {
	var a, b;
	try {
	[a] = yield make_async_work('inside 1');
	} catch (exc) {
	console.log("Caught Exception", exc);
	a = 'thank';
	}

	try {
	[b] = yield fail_work('inside 2');
	} catch (exc) {
	console.log("Caught Exception", exc);
	b = 'goodness';
	}

	console.log("Yielding return", a + b + 'return value');

	yield a + b + 'return value';
	}

	function outside_function() {
	[b] = yield function (callback) {
	setTimeout(function () {
	__gen(inside_function)(function (result) {
	console.log("Result inside b.", result);
	callback(result);
	});
	}, 500)
	}
	console.log("Yielded b");

	yield b;
	}

	__gen(outside_function)(function (result) {
	console.log(result + ' outside value');
	});

	fnGen(17, function (result) {
	console.log("Finished!", result);
	});

	fnGen(27);
	</script>

	<script type="application/coffeescript-fork">

	serverRequest = (args..., callback) ->
	setTimeout ->
	callback.apply({}, i + 10 for i in args)
	, 500

	# fnGen is an asynchronously called function with an implicit final
	# completion callback after the defined arguments.

	# the ~> defines a generatorLoop wrapped function which uses the generator
	# to sychronise by doing async processing in a yield -> evaluate -> send loop.

	# <~ defines a blocking call to a asynchronous function, with a completion
	# callback passed as a final parameter if a function or function call, otherwise
	# followed by a named completion callback.

	fnGen = (d) ~>

	# Implicit completion callback with other arguments
	[a] <~ serverRequest 20

	# Named explicit completion callback
	[b, c] <~ finish
	doServerRequest 10, (n) ->
	finish n, n - 15

	# Implicit completion callback with no arguments
	[e] <~ serverRequest

	console.log a, b, c, d, e
	# a = 20 + 10
	# b = 10 + 10
	# c = 10 + 10 - 15
	# d = d
	# e = undefined

	# Nesting
	[f] <~ finish
	nested = ~>
	[a] <~ serverRequest 60
	[b] <~ serverRequest 40

	a + b

	nested (c) ->
	finish c

	# Nesting silly.
	[f] <~ ~>
	[a] <~ serverRequest 60
	[b] <~ serverRequest 40

	a + b

	console.log f
	# f = 120

	# implicit return yield
	[a, b, c]

	fnGen 5, (results) ->
	console.log(results); # [30, 20, 5]
	console.log "Finished!"
	</script>
	</html>