Rationale - YannickDot/Taskorama GitHub Wiki

I created this lib when I tried to implement Tasks in JavaScript in order to understand how do they work.

I like using Promises but they have major design flaws IMHO :

• They run as soon as the promise is declared : what if I want to defer the computation ?
• They are async by default : i.e. Promise.resolve(2) always runs on the next tick
• They are not cancellable (it's unfortunate that we can't cancel window.fetch http request when necessary)

Tasks happen to be really simple and have richer semantics than Promises :

• Tasks are pure : they do not perform any side-effect as long as they are not executed by calling .fork() .
• Tasks make a clear separation between definition and execution, while Promises mix the two. @andrestaltz explained it way better than me in this comment

So I decided to replace Promises by Tasks in my code in order to separate pure data processing resulting of an async computation and side-effects.

I started this project after watching this talk about Observables.

The internals of Taskorama are similar to the one used in case explained in this video.