Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Add pipeline operator "loose" mode #10135

Open
jhpratt opened this issue Jun 26, 2019 · 1 comment

Comments

Projects
None yet
3 participants
@jhpratt
Copy link

commented Jun 26, 2019

Feature Request

Right now, the pipeline operator (|>) always creates a temporary variable to store a reference. Per the spec, this is correct, as evaluation order is different. What I'm asking is for that to not be the case (given a "loose" option). A "loose" option is present for multiple other proposals, so it's not without precedent.

Here's an example from the pipeline proposal.

input
|> # - 3
|> -#
|> # * 2
|> Math.max(#, 0)
|> console.log;

Current transformation:

var _ref, _ref2, _ref3, _ref4, _input;

_ref = (
  _ref2 = (
    _ref3 = (
      _ref4 = (
        _input = input,
        _input - 3
      ),
      -_ref4
    ),
    _ref3 * 2
  ),
  Math.max(_ref2, 0)
),
console.log(_ref);

Proposed transformation:

console.log(
  Math.max(
    -(input - 3) * 2,
    0
  )
);

To avoid wasted effort, it's probably best to wait until TC39 settles on a specific syntax proposal before implementing, as there are many, and Babel will support 3 (minimal, smart, and F#) as of Babel 7.5.

@babel-bot

This comment has been minimized.

Copy link
Collaborator

commented Jun 26, 2019

Hey @jhpratt! We really appreciate you taking the time to report an issue. The collaborators
on this project attempt to help as many people as possible, but we're a limited number of volunteers,
so it's possible this won't be addressed swiftly.

If you need any help, or just have general Babel or JavaScript questions, we have a vibrant Slack
community
that typically always has someone willing to help. You can sign-up here
for an invite.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.