[ruby-core:52859] [ruby-trunk - Feature #7939] Alternative curry function creation

Issue #7939 has been updated by marcandre (Marc-Andre Lafortune).


phluid61 (Matthew Kerwin) wrote:
> As a philosophical question, would a name like #curry_with or #apply be more appropriate?  There is a small amount of utility added by such a method:  at first glance I didn't see the .curry on the end of the first line of Nobu's example, and it took a bit of effort on my part to parse the code (or its intent);  however the call to .assuming made it clear that something different was intended and happening at that point.
> 
> The square-bracket invocation falls somewhere in between, in terms of readability.  It may just be me, but sometimes I temporarily fail to grasp that foo.bar[baz] is actually two chained method calls.  In this case it was counfounded by the fact that I forgot that Proc#curry has an optional arity parameter.  I know that those are my issues, that it is up to me to overcome, but having such hints in the code can help.

There are many different ways to write the given example. You seem to be willing to use [] since your last line also has [] in it. But you can use .call or even .():

fb = ->(modulo_number, message, x) { message if x % modulo_number == 0 }
       .curry  # <---- difficult to miss if it's at the beginning of a line
fizzbuzz = fb.(15,"FizzBuzz")
fizz = fb.(3, "Fizz")
buzz = fb.(5, "Buzz")
(1..100).each { |i| puts fizzbuzz.(i) || fizz.(i) || buzz.(i) || i }

You can use all of them if you want...

fb = ->(modulo_number, message, x) { message if x % modulo_number == 0 }
fizzbuzz = fb.curry.(15,"FizzBuzz")
fizz = fb.curry.call(3, "Fizz")
buzz = fb.curry[5, "Buzz"]
(1..100).each { |i| puts fizzbuzz.(i) || fizz.call(i) || buzz[i] || i }

I feel that each of these variations is easier to understand than your proposition. Moreover, I use `curry` very rarely, so I see no use in adding a new method.

As for the name, I feel the one proposed was quite bad, but I don't think there is a really good one. The only name that would really fit is "curry_call", which is exactly what it is doing. I see no point in exchanging "curry.call" with "curry_call"...
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Feature #7939: Alternative curry function creation
https://bugs.ruby-lang.org/issues/7939#change-36972

Author: drKreso (Kresimir Bojcic)
Status: Assigned
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: core
Target version: next minor


=begin
I really like the new "(({assuming}))" method used for currying in Perl 6.

For example if I loose my mind and implement ((%fizzbuzz%)) via currying I can do it like this:

  fb = ->(modulo_number, message, x) { message if x % modulo_number == 0 }
  fizzbuzz = fb.curry[15,"FizzBuzz"]
  fizz = fb.curry[3, "Fizz"]
  buzz = fb.curry[5, "Buzz"]
  (1..100).each { |i| puts fizzbuzz[i] || fizz[i] || buzz[i] || i }

Here the first hurdle is that curry is somewhat mathematical, and the secons is that you need to use (({[]})) for function invoking...
If we had something similar to this:

  class Proc
    def assuming(*args)
      curry.call *args
    end
  end

It could be written more naturally IMO:

  fb = ->(modulo_number, message, x) { message if x % modulo_number == 0 }
  fizzbuzz = fb.assuming(15,"FizzBuzz")
  buzz = fb.assuming(5, "Buzz")
  fizz = fb.assuming(3,"Fizz")

  (1..100).each { |i| puts fizzbuzz[i] || fizz[i] || buzz[i] || i }
=end



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