Hate this implicit return statement. Proposal to add returnless function arrow

[yivo]

Hello guys! Thank you for creating and supporting CoffeeScript!

Often when I want to extract loop to separate method I write like this:

performEach = ->
  el.perform() for el in collection

But always getting loop which collects returned data from el.perform():

var performEach;

performEach = function() {
  var el, i, len, results;
  results = [];
  for (i = 0, len = collection.length; i < len; i++) {
    el = collection[i];
    results.push(el.perform());
  }
  return results;
};

Then I add explicit return statement:

performEach = ->
  el.perform() for el in collection; return

And getting what I want:

var performEach;

performEach = function() {
  var el, i, len;
  for (i = 0, len = collection.length; i < len; i++) {
    el = collection[i];
    el.perform();
  }
};

Proposal! What do you think about returnless arrow? Something like this:

performEach = |> # Note new syntax: "|>". Fat arrow syntax: "||>" 
  el.perform() for el in collection

Compiles to:

var performEach;

performEach = function() {
  var el, i, len;
  for (i = 0, len = collection.length; i < len; i++) {
    el = collection[i];
    el.perform();
  }
};

For many APIs is it important what value was returned (for example it is event handlers in jQuery).
Also there is article about it http://programmaticallyspeaking.com/why-i-hate-implicit-return-in-coffeescript.html

[bjmiller]

This has been asked and rejected more times than I can remember off hand.

In 99% of cases, you either want the last statement of the function to be the return value, or the return value is thrown away and it doesn't matter.

For the remaining 1% of cases, you can type return at the end of the function, which is much more explicit about your intent, and less complex than Yet Another Operator.

Can people PLEASE stop asking for this not-a-feature now?

[loveencounterflow]

this wouldn't be an issue if CS had "use strict"-like per module / per function configuration settings ('pragmas', similar to Python's from __future__ import).

Personally I use return null all over the place to prevent my functions from accidentally 'leaking' values. In my experience implicit return looks attractive in theory but turns out to be a liability in the majority of cases, the exception typically being simple one-liners.

I'd be totally OK with an explicit syntax for implicit returns (say, cube = ( x ) <-> x ** 3), but removing implicit return in the absence of 'pragmas' will break backwards compatibility in ways that nobody will support.

[carlsmith]

I always use explicit returns unless it's a single expression these days, and would have personally preferred that syntax, but I still don't think it's worth changing CoffeeScript by adding modes at this stage. There's a lot of good ideas for how CoffeeScript could have been improved, but they should just influence new languages.