xtodo js promise

js promise

• For computer scientists.
• JS promise, the most complicated thing.
• I still don't fully understand it.
• Am relating it to call with continuation and concurrency issues.
• I need to understand and explain it in terms of loop and check.
• If you do, explain please.
• I likely won't get good answers. but i'll grade your answer, and explain the flaws.

• Alternatively, what is analogous feature in other programing language? Any?
• What is its history?
• This would also explain and put a judgement of controversy about non-blocking in nodejs 15 years ago.

• actually, gonna try asking grok.

• Basically what I'm looking for is to explain JS's promise in terms of lambda calculus, or an implementation in a basic turing complete programming language, such as basic bash or Python.

• The history goes back to MochiKit implementing Twisted (a Python library) Deferreds in JS.
• Dojo Toolkit borrowed the concept from MochiKit (I think MochiKit's author donated the code to Dojo).
• Promises ended up being a subset of Deferred functionality.
• Links to follow:

• https://dojotoolkit.org/reference-guide/1.10/dojo/Deferred.html

• Also, @kriszyp, @slightlylate, @phiggins, @dylans, @ttrenka, and many others I can't remember were instrumental in getting Deferreds and Promises into JS 20+ years ago.
• It was an honor working with them back then.

• Manuel Simoni
• @msimoni
• Fundamentally, it's a way to make callbacks (which is the only way you can do IO in JS) more palatable, by wrapping them in a convenient object.
• There's quite a bit going on; look into a pure-JS implementation of the "Promises/A+" spec such as this one:
• https://github.com/abdulapopoola/Adehun/blob/master/adehun.js

• adehun.js

• JS: Promise Tutorial

promisesaplus

• https://promisesaplus.com/

dojo Deferred