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Feature #6817

open

Partial application

Added by citizen428 (Michael Kohl) over 11 years ago. Updated about 6 years ago.

Status:
Open
Target version:
-
[ruby-core:46889]

Description

I know that what I propose here is a significant change to Ruby, but it's part of my ongoing quest to get some more functional programming features into Ruby (see also #4539 and #6373).

I was wondering if it would make sense to maybe introduce partial application to Ruby? So that instead of

(1..3).map { |i| i + 2 }

or the somewhat unwieldy

(1..3).map(&2.method(:+))

one could just write

(1..3).map(&2.+)

which I think has a quite rubyish feel to it. I have a POC implementation in Ruby (I tried it with various Fixnum methods) over at my blog, but that was just a quick hack and obviously I don't want to monkey-patch every method with arity 1, but it was a nice way of exploring possible syntax.


Related issues 4 (2 open2 closed)

Related to Ruby master - Feature #4539: Array#zip_withAssignedmatz (Yukihiro Matsumoto)Actions
Related to Ruby master - Feature #6373: public #selfClosedmatz (Yukihiro Matsumoto)Actions
Related to Ruby master - Feature #7939: Alternative curry function creationFeedbackmatz (Yukihiro Matsumoto)Actions
Related to Ruby master - Feature #13765: Add Proc#bindOpenActions

Updated by shyouhei (Shyouhei Urabe) over 11 years ago

  • Description updated (diff)

Updated by yhara (Yutaka HARA) over 11 years ago

  • Target version changed from 2.0.0 to 2.6

Updated by ko1 (Koichi Sasada) about 11 years ago

  • Assignee set to matz (Yukihiro Matsumoto)

This ticket is related to [ruby-core:52797] [ruby-trunk - Feature #7939]?
(definitely no?)

Basically, I like this proposal.
But I'm not sure this notation can be acceptable.

FYI: Scheme has similar, but more flexible proposal:
http://srfi.schemers.org/srfi-26/srfi-26.html

(cut cons (+ a 1) <>) is the same as (lambda (x2) (cons (+ a 1) x2))
(cut list 1 <> 3 <> 5) is the same as (lambda (x2 x4) (list 1 x2 3 x4 5))
(cut list) is the same as (lambda () (list))
(cut list 1 <> 3 <...>) is the same as (lambda (x2 . xs) (apply list 1 x2 3 xs))
(cut <> a b) is the same as (lambda (f) (f a b))

Of course, it is not ruby's way. This is only sample of the other language.

Updated by citizen428 (Michael Kohl) over 9 years ago

Koichi Sasada wrote:

Basically, I like this proposal.
But I'm not sure this notation can be acceptable.

In that case, how about making Symbol#to_proc accept additional arguments?

(1..3).map(:+, 2) 

The syntax would be very straightforward, but it doesn't go well with the current implementation of Symbol#to_proc's proc cache. Also this does go away a bit from the original point of partial application, though tbh this sort of scenario is what I mostly had in mind anyway.

Updated by nobu (Nobuyoshi Nakada) over 9 years ago

  • Description updated (diff)

Michael Kohl wrote:

In that case, how about making Symbol#to_proc accept additional arguments?

(1..3).map(:+, 2) 

It doesn't relate to Symbol#to_proc.

Actions #6

Updated by k0kubun (Takashi Kokubun) over 6 years ago

  • Related to Feature #7939: Alternative curry function creation added
Actions #7

Updated by k0kubun (Takashi Kokubun) over 6 years ago

Actions #8

Updated by naruse (Yui NARUSE) about 6 years ago

  • Target version deleted (2.6)
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