[Haskell-cafe] Signature for non-empty filter

[Bulat Ziganshin]

Hello Henning,

Tuesday, February 5, 2008, 6:01:27 PM, you wrote:

> Is Haskell's type system including extensions strong enough for describing
> a function, that does not always return a trivial value? E.g.
>    (filter (\x -> x==1 && x==2))

such things may be detected by (too) smart compiler, but in general
it's undecidable: filter (if LifeHasMeaning then const True else odd) ;)

-- 
Best regards,
 Bulat                            mailto:Bulat.Ziganshin at gmail.com