From: Avdi Grimm <avdi@...>
Date: 2015-01-11T13:56:56-05:00
Subject: [ruby-core:67513] Refinements on modules?

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The other day on the Ruby Rogues forum, someone asked how to idiomatically
write the following Clojure example in Ruby:

    (take 25 (squares-of (integers)))

My answer was:

  0.step.lazy.map{ |n| n**2 }.take(25).to_a

...which I'm pretty happy with, since it's reasonably concise and preserves
the laziness of the Clojure version.

The only part that bothered me was the squaring calculation: map{ |n| n**2 }

Presumably, `squares-of` is a Clojure built-in. I don't think Ruby should
add this to Enumerable; it's far too niche a use case. But I wanted a way
to insert a Ruby-ish squares_of directly into the chain of operations, like
this:

  0.step.lazy.squares.take(25).to_a

Obviously I could monkeypatch Enumerable to get this. But I thought it
would be nicer to make the patch non-invasive using refinements. And here's
where I ran into a snag: you can't refine modules.

I wound up refining Enumerator:

  module Squares
    refine Enumerator do
      def squares
        map{ |n| n**2 }
      end
    end
  end

  using Squares

  0.step.lazy.squares.take(5).to_a # => [0, 1, 4, 9, 16]

This works fine. But I'm bothered by refining Enumerator instead of
Enumerable. It means that the refinement isn't generic. In order to have
consistency, I have to know exactly what class[es] might be involved, and
refine all of them.

This doesn't feel very duck-type friendly. And the more I think about uses
of refinements, the more I think of wanting to refine modules that are
widely included, such as Enumerable or Comparable.

So my question is: is this a feature that is coming?

--
Avdi Grimm
http://avdi.org

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<div dir=3D"ltr"><div>The other day on the Ruby Rogues forum, someone asked=
 how to idiomatically write the following Clojure example in Ruby:</div><di=
v><br></div><div>=C2=A0 =C2=A0=C2=A0(take 25 (squares-of (integers)))</div>=
<div><br></div><div>My answer was:</div><div><br></div><div>=C2=A0=C2=A00.s=
tep.lazy.map{ |n| n**2 }.take(25).to_a</div><div><br></div><div>...which I&=
#39;m pretty happy with, since it&#39;s reasonably concise and preserves th=
e laziness of the Clojure version.</div><div><br></div><div>The only part t=
hat bothered me was the squaring calculation: map{ |n| n**2 }</div><div><br=
></div><div>Presumably, `squares-of` is a Clojure built-in. I don&#39;t thi=
nk Ruby should add this to Enumerable; it&#39;s far too niche a use case. B=
ut I wanted a way to insert a Ruby-ish squares_of directly into the chain o=
f operations, like this:</div><div><br></div><div>=C2=A0 0.step.lazy.square=
s.take(25).to_a</div><div><br></div><div>Obviously I could monkeypatch Enum=
erable to get this. But I thought it would be nicer to make the patch non-i=
nvasive using refinements. And here&#39;s where I ran into a snag: you can&=
#39;t refine modules.</div><div><br></div><div>I wound up refining Enumerat=
or:</div><div><br></div><div><div>=C2=A0 module Squares</div><div>=C2=A0 =
=C2=A0 refine Enumerator do</div><div>=C2=A0 =C2=A0 =C2=A0 def squares</div=
><div>=C2=A0 =C2=A0 =C2=A0 =C2=A0 map{ |n| n**2 }</div><div>=C2=A0 =C2=A0 =
=C2=A0 end</div><div>=C2=A0 =C2=A0 end</div><div>=C2=A0 end</div><div><br><=
/div><div>=C2=A0 using Squares</div><div><br></div><div>=C2=A0 0.step.lazy.=
squares.take(5).to_a # =3D&gt; [0, 1, 4, 9, 16]</div></div><div><br></div><=
div>This works fine. But I&#39;m bothered by refining Enumerator instead of=
 Enumerable. It means that the refinement isn&#39;t generic. In order to ha=
ve consistency, I have to know exactly what class[es] might be involved, an=
d refine all of them.=C2=A0</div><div><br></div><div>This doesn&#39;t feel =
very duck-type friendly. And the more I think about uses of refinements, th=
e more I think of wanting to refine modules that are widely included, such =
as Enumerable or Comparable.</div><div><br></div><div>So my question is: is=
 this a feature that is coming?</div><br clear=3D"all"><div><div class=3D"g=
mail_signature"><div dir=3D"ltr"><div>--</div>Avdi Grimm<br><a href=3D"http=
://avdi.org" target=3D"_blank">http://avdi.org</a><br><br></div></div></div=
>
</div>

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