[Haskell-cafe] Re: [Haskell] Re: View patterns in GHC: Request for feedback

[Claus Reinke]

>>    unit :: Typ -> Maybe ()
>>    arrow :: Type -> Maybe (Typ,Typ)
>>    size :: Typ -> Integer
>>    size (unit -> ()) = 1
>>    size (arrow -> (t1,t2)) = size t1 + size t2

> Though I guess you would not object to:
> 
> size (unit -> Just ()) = 1
> size (arrow -> Just (t1,t2)) = size t1 + size t2
> ?

actually, i might!-) it is not just that, in general, you have to invent 
and declare those intermediate view types, but that their use obscures
the overall pattern, once you start nesting abstract and concrete 
patterns (and if you don't nest them, view patterns don't add much).

claus