JSHint compatibility

[adambene]

When the return value of an async operation is not assigned to a variable, then the result translates into a single expression and it raises a JSHint error.

set timeout! ^ 1000
log "Hello World!"

translates to

(function() {
    var Promise = require("bluebird");
    var gen1_promisify = function(fn) {
        return new Promise(function(onFulfilled, onRejected) {
            fn(function(error, result) {
                if (error) {
                    onRejected(error);
                } else {
                    onFulfilled(result);
                }
            });
        });
    };
    var self = this;
    var gen2_asyncResult;
    new Promise(function(gen3_onFulfilled) {
        gen3_onFulfilled(gen1_promisify(function(gen4_callback) {
            return setTimeout(gen4_callback, 1e3);
        }).then(function(gen2_asyncResult) {
            gen2_asyncResult; // <===== the JSHint error is here
            return log("Hello World!");
        }));
    });
}).call(this);

JSHint error on line 20:

20: Expected an assignment or function call and instead saw an expression