Re: Proc#curry

On Feb 27, 2:21m, Trans <[e-mail]> wrote:
> On Feb 16, 8:20 am, Lin Jen-Shin <[e-mail]> wrote:
> > godfat ~> irb
> > irb(main):001:0> require 'rubygems'
> > => true
> > irb(main):002:0> require 'ludy/proc'
> > => true
> > irb(main):003:0> lambda{|x,y,z|[x,y,z]}.curry.bind(:_1, 2, :_2)[1,3]
> > => [1, 2, 3]
>
> I suspect you did not need the call to #curry there?

Yes, you're right. I forgot to fix my example there (it's just simply
copied from rdoc), and later I changed the example to:

lambda{|x,y,z|[x,y,z]}.curry.bind(:_1, 2, :_2)[1][3]

I found that it didn't work as I expected, [1,2,3] but nil instead.
It came from calling [1,2,nil][3]. The curry thing didn't work on
bind.
I think I would spend some time on fixing this.

> Interesting, does it allow .bind(:_1, 2, :_1)[3] ?

Yes, it was allowed. The result would be [3,2,3].
Bind just simply creates a lambda which rearranges the arguments
for the calling Proc object.

> > I am glad to see Proc#curry can be added into core, not supporting
> > with library,
> > but I didn't see there's Proc#uncurry as well. I hope there's one too.
>
> Is it a full reversible processes?

Yes, it is. See example in Haskell, which make all function
default to be curried. I won't explain the example here because
this is ruby-core mailing list, neither Haskell nor functional
programming.
I am very glad to see if more FP stuffs are added into ruby core
language.

godfat ~> ghci
GHCi, version 6.8.2: http://www.haskell.org/ghc/  :? for help
Loading package base ... linking ... done.
Prelude> let func = \x y -> x + y
Prelude> func 1 2
3
Prelude> (func 1) 2
3
Prelude> :type func
func :: Integer -> Integer -> Integer

Prelude> uncurry func (1,2)
3
Prelude> :type uncurry func
uncurry func :: (Integer, Integer) -> Integer

Prelude> curry (uncurry func) 1 2
3
Prelude> :type curry (uncurry func)
curry (uncurry func) :: Integer -> Integer -> Integer

> T.