Promises are the monad of asynchronous programming – The If WorksIn my introduction to monads in JavaScript we saw a couple of monads and examined the commonality between them to expose an underlying design pattern. Before I get on to how that applies to asynchronous programming we need to take one final diversion and discuss polymorphism. Consider the list monad that we implemented before: var compose = function(f, g) { return function(x) { return f(g(x)) }; }
