channels

go.js

var chan = function () {
    return [];
};

var toString = Object.prototype.toString;

function go( machine, chan ) {
    var gen = machine( chan );
    _go( gen, gen.next() );
}

function _go( machine, step ) {
    while ( !step.done ) {
        if( toString.call( step.value ) === "[object Function]" ) {
            var arr = step.value();
            var state = arr[0];
            var value = arr[1];

            switch( state ) {
                case "park": setImmediate( function() { _go( machine, step ); } ); return;
                case "continue": step = machine.next( value ); break;
            }
        } else if ( toString.call( step.value ) === "[object Object]" ) { //must be "[object Promise]"
            step.value.then( function ( value ) {
                _go( machine, machine.next( value ) );
            } );
            setImmediate( function() { _go( machine, step ); } ); return;
        } else {
            console.log( toString.call( step.value ) );
            throw Error('Incorrect yield');
        }
    }
}

function put( chan, value ) {
    return function() {
        if( chan.length === 0 ) {
            chan.unshift( value );
            return [ "continue", null ];
        } else {
            return [ "park", null ]
        }
    }
}

function take( chan ) {
    return function() {
        if( chan.length == 0 ) {
            return [ "park", null ];
        } else {
            return [ "continue", chan.pop() ];
        }
    }
}

var ch = chan();

go(function* ( ch ) {
    var i = 0;
    for( ; i < 10; i++ ) {
        yield put( ch, i );
    }
    var val = yield new Promise( function ( resolve ) {
        setTimeout( function () {
            resolve( 'Hello from promise!' );
        }, 1000 );
    } );
    yield put( ch, val );
    yield put( ch, 'And again in channel!' );
    yield put( ch, null );
}, ch);

go(function* ( ch ) {
    var value;
    while( ( value = yield take( ch ) ) !== null ) {
        console.log( 'Take: ', value );
    }
}, ch);