[Haskell-cafe] Article review: Category Theory

Joachim Breitner mail at joachim-breitner.de
Thu Jan 18 11:18:13 EST 2007


Hi,

Am Donnerstag, den 18.01.2007, 15:05 +0100 schrieb Ulf Norell:
>    _|_ . id = \x -> _|_ ≠ _|_

Isn’t _|_ = \x -> _|_? Or better stated: For your first _|_ to be used
in (.), it has to take an argument, therefore it is \x -> _|_.

(.) :: (b -> c) -> (a -> b) -> a -> c
id :: a -> a
therefore b = a
therefore _|_ :: a -> c

(This is mostly rough guesswork, I might be totally wrong)

Joachim
-- 
Joachim Breitner
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