Coffee-script support for promises?

[iamwilhelm]

(I would search issues first if I could), but I was wondering if coffeescript had ever entertained a syntax to make it less messy to write promises?

when using promises, it usually looks pretty messy, because you have to wrap it inside of the promises functions, and you have to 'lift' the functions.

wn = require('when')
wnf = require('when/node/function')

wn(
  wnf.lift(method)(arg)
).then(
  wnf.lift(method2)(arg1, arg2)
).then((result) ->
  callback(result)
).otherwise((err) ->
  callback(err)
)

I was wondering if coffeescript would entertain having syntax that makes it easier.

wn(
  ^method(arg) ;;
  ^method2(arg1, arg2) ;result;
  callback(result) |err|
    callback(err)
)

I just made that up on the spot, just to illustrate a possible syntax. I'm not sure there needs to be a difference between ;; and || for then() and otherwise()

[vendethiel]

(I would search issues first if I could),

You can ! Here :

when using promises, it usually looks pretty messy, because you have to wrap it inside of the promises functions, and you have to 'lift' the functions.

Why so ? You're only using a poor style to write them, imho. This works and is quite clear :

wn = require('when')
wnf = require('when/node/function')

wn ->
  method arg
.then ->
  method arg
.then ->
  method arg, arg2
.then (result) ->
  callback result
.otherwise (err) ->
  callback err

I was wondering if coffeescript would entertain having syntax that makes it easier.

I don't see a special syntax for promises being added. The syntax you proposed is clearly far too cryptic and would be a no-go for me (if proposed seriously).
However, we have #2762 for backcalls (which actually doesn't really help here).

[michaelficarra]

This is a duplicate of #1495. That thread is huge now.