As mentioned elsewhere, is this currying? Or partial application?

Currying:

lambda { |x,y| x + y }.curry => lambda { |x| lambda { |y| x + y } }

Partial Application

lambda { |x, y| x + y }.apply(2) => lambda { |y| 2 + y }

And given #curry, #apply is trivial:

class Proc; def apply(param); self.curry.call(param); end end

...or at least, that's my understanding...

i think you're right.

After learning about these concepts in Haskell, the Ruby code seems downright ugly (I never thought I'd say that)... but still probably quite useful in some cases.

raganwald, u r totally right, i have updated the post to show the diff.