Re: [Haskell-cafe] Re: Wikipedia on first-class object

31 Dec 2007


      Nice! Thank you.

On Mon, 31 Dec 2007 12:56:42 +0200, Ryan Ingram   
wrote:
...
On 12/30/07, Cristian Baboi  wrote:
...
Thank you.
data Something = This | S Something
ppp :: Something -> String
ppp This = ""
ppp (S x) = 'S':(ppp x)
How can I prevent one to pass  'let x = S x in x' to ppp ?
{-# LANGUAGE GADTs, EmptyDataDecls #-}
data Z
data S a
data Something a where
    This :: Something Z
    S :: Something a -> Something (S a)
ppp :: Something a -> String
ppp This =  ""
ppp (S x) = 'S' : ppp x
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  part000.txt - is OK
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