[Haskell-cafe] Re: The Worker/Wrapper Transformation

Achim Schneider wrote:

"Brent Yorgey" wrote:

...

Well, (:) has type a -> [a] -> [a], so a function corresponding to (:) for Hughes lists should have type

foo :: a -> H a -> H a

[...] I think the key sentence from the paper is this: "by representing a list xs as the function (xs ++) that appends this list to another list that has still to be supplied." If you understand that sentence, then you can understand why [] is id and (++) is (.).

Yes, I did.

They key was not thinking that : has type

(:) :: a -> a -> [a]

, or, put differently, beat the lisp out of me, thanks.

What the hell am I talking about? (define (cons x y) (lambda (m) (m x y))) (define (car z) (z (lambda (p q) p))) (define (cdr z) (z (lambda (p q) q))) : is, in a sense, \. -- (c) this sig last receiving data processing entity. Inspect headers for past copyright information. All rights reserved. Unauthorised copying, hiring, renting, public performance and/or broadcasting of this signature prohibited.