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

Achim Schneider barsoap at web.de
Thu Jan 3 07:15:15 EST 2008

"Brent Yorgey" <byorgey at gmail.com> 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.

The problem is merely that Haskell and lisp are too similar in a much
too different way.

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