From: "Wolfgang Nádasi-Donner" <ed.odanow@...>
Date: 2008-02-16T22:18:32+09:00
Subject: Re: Proc#curry

Yukihiro Matsumoto schrieb:
>   proc {|x, y, z| x + y + z }.curry
> 
> returns the proc object equivalent to
> 
>   proc {|x| proc {|y| proc {|z| x + y + z } } }

This is what I would expect from "currying" (or sch��nfinkeln). So I 
would expect, that the calls will be...

proc {|x, y, z| x + y + z }[1,2,3]
proc {|x, y, z| x + y + z }.curry[1][2][3]

...with the same result, but that...


proc {|x, y, z| x + y + z }.curry[1,2,3]

would fail with the message "3 parameters instead of 1". I'm a little 
bit surprized, that ist works...

boviMacBook:~ bovi$ ruby19 --version
ruby 1.9.0 (2008-02-16 revision 0) [i686-darwin9.1.0]
boviMacBook:~ bovi$ irb19
irb(main):001:0> f = proc{|a,b,c|a+b+c}
=> #<Proc:0x3ce9c0@(irb):1>
irb(main):002:0> g = f.curry
=> #<Proc:0x3cc2d8>
irb(main):003:0> f[1,2,3]
=> 6
irb(main):004:0> g[1][2][3]
=> 6
irb(main):005:0> def otto(fun)
irb(main):006:1>   fun[3,4]
irb(main):007:1> end
=> nil
irb(main):008:0> r = proc{|k,l|k*l}
=> #<Proc:0x3bc0b8@(irb):8>
irb(main):009:0> s = proc{|m,n,o|m+n+o}.curry
=> #<Proc:0x3b69ec>
irb(main):010:0> otto(r)
=> 12
irb(main):011:0> otto(s[2])
=> 9

Is this an accident or done by intention. If it is done by intention it 
is nice, because otherwise I must implement an application which uses 
currying with currying all Proc objects that use more than one parameter.

Wolfgang N��dasi-Donner