[Haskell-cafe] non-alphabetical mathematical symbols as non-infix function names

Miguel Mitrofanov miguelimo38 at yandex.ru
Tue Jan 22 01:23:50 EST 2008


MigMit:~ MigMit$ ghci
GHCi, version 6.8.2: http://www.haskell.org/ghc/  :? for help
Loading package base ... linking ... done.
Prelude> let {(¬) :: Bool -> Bool; (¬) = not}
Prelude> (¬) True
False

On 22 Jan 2008, at 09:03, Cetin Sert wrote:

> (¬) :: Bool → Bool
> (¬) q = not q
>
> q = True
> ¬ q : parser error on input
> q ¬ : parser error (possibly incorrect indentation)
> (¬ q) : Couldn't match expected type `Bool -> t' against inferred  
> type `Bool' In the expression: (� True) In the definition of `it':  
> it = (� True) *
> (q ¬) : False
>
> (Why) is it not possible to define a (non-infix) function whose name  
> consists of a single non-alphabetical mathematical symbol?
>
> ¬ :: Bool → Bool -- parser error on input **
> ¬ q = not q -- parser error on input **
>
> Cetin Sert
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