ruby-core

Issue #6284 has been updated by Tom Stuart.


I support the proposed `Proc#*`/`Method#*` syntax and semantics.

The feature being added is **function composition**; not relation composition, not method chaining. Its target audience is most likely to read `f * g` as “`f` after `g`”, so that’s how it should work. Perhaps some Ruby programmers will not use this feature directly (as with `Proc#curry`) because they neither program nor think in a functional style, but it should be designed to be useful and familiar to those who do. The proposed implementation achieves that.

The asterisk isn’t ideal, but it’s the best choice available.

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Feature #6284: Add composition for procs
https://bugs.ruby-lang.org/issues/6284#change-53231

* Author: Pablo Herrero
* Status: Feedback
* Priority: Normal
* Assignee: Yukihiro Matsumoto
----------------------------------------
=begin
It would be nice to be able to compose procs like functions in functional programming languages:

    to_camel = :capitalize.to_proc
    add_header = ->val {"Title: " + val}

    format_as_title = add_header << to_camel << :strip

instead of:

    format_as_title = lambda {|val| "Title: " + val.strip.capitalize }


It's pretty easy to implement in pure ruby:

  class Proc
    def << block
      proc { |*args| self.call( block.to_proc.call(*args) ) }
    end
  end
=end

---Files--------------------------------
0002-proc.c-Implement-Method-for-Method-composition.patch (2.71 KB)
0001-proc.c-Implement-Proc-for-Proc-composition.patch (3.73 KB)
0003-proc.c-Support-any-callable-when-composing-Procs.patch (4.01 KB)


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