From: Michael Fellinger <m.fellinger@...>
Date: 2007-05-29T16:17:17+09:00
Subject: Re: Underscore

some people use _ as a temporary meaningless variable, just a
throw-away so to say.
In this case something like

hash = {:a => :b, :c => :d}

and you are not interested in the :b and :d

hash.each do |key, _|
  p key
end

I'm not necessarily a friend of this technique, but it seems easy on
the minds of some people.

^ manveru

On 5/29/07, Jon Harrop <jon@ffconsultancy.com> wrote:
> Logan Capaldo wrote:
> >> > However, I'd probably write it like:
> >> >   def nest(x, n = 2)
> >> >     (1..n).inject(x) { |acc, _| yield(acc) }
> >> >   end
> >>
> >> I don't understand this one. I think "inject" is a fold and "yield"
> >> returns a value and a continuation. Looks like the continuation is
> >> ignored the next time it is accumulated, but won't the result have a
> >> continuation in it?
> > inject is a fold. yield is not a continuation, but rather a way of
> > accessing the passed in function (block) anonymously.
> >
> > def f
> >   yield
> > end
> >
> > def f1(&b)
> >   b.call
> > end
> >
> > f { puts "Does the same thing" }
> > f1 { puts "Does the same thing" }
>
> I see. So that was equivalent to:
>
>   let rec nest ?(n=2) x f =
>     Seq.fold (fun acc -> f acc) x {1 .. n}
>
> but what is the meaning of the "_" in the Ruby "|acc, _|"?
>
> --
> Dr Jon D Harrop, Flying Frog Consultancy
> The F#.NET Journal
> http://www.ffconsultancy.com/products/fsharp_journal/?usenet
>
>