[Haskell] Re: View patterns in GHC: Request for feedback
Rene de Visser
Rene_de_Visser at hotmail.com
Tue Jul 24 14:05:13 EDT 2007
"Claus Reinke" <claus.reinke at talk21.com> schrieb im Newsbeitrag
news:004a01c7cde1$04b190f0$2e3f8351 at cr3lt...
>> though I'm extremely dubious about the utility of the "Maybe" patterns.
> actually, they are the main thing that interests me about view patterns!-)
> type Typ
> unit :: Typ -> Maybe ()
> arrow :: Type -> Maybe (Typ,Typ)
> size :: Typ -> Integer
> size (unit -> ()) = 1
> size (arrow -> (t1,t2)) = size t1 + size t2
> closer to ordinary patterns, with the lowercase and the '->' hinting
> that there is computation before matching (well, '=>', according to
> the new proposal).
Though I guess you would not object to:
size (unit -> Just ()) = 1
size (arrow -> Just (t1,t2)) = size t1 + size t2
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