Using Set: Hypergraph type

Daan Leijen [email protected]
Tue, 4 Sep 2001 16:27:44 +0200


Hi Eray,

> Hypergraph> :type hgraph [ [1,2], [1] ]
> forall a. (Num a, Ord (Set a), Ord a) => Set (Set a)
> Hypergraph> elementOf (mkSet [1]) (hgraph [ [1,2], [1] ])
> [type errors]


Unfortunately, you don't show the type error that
was returned. However, I think that Hugs/GHCi
is unable to figure out which numeric (Num a)
instance you are using (Int,Integer, Double??).
You can help the interpreter a little bit by
providing a type annotation:

> elementOf (mkSet [(1::Int)]) (hgraph [ [1,2], [1] ])

or a constant with a type signature

> list1 :: [Int]
> list1  = [1]
>
> test =  elementOf (mkSet list1) (hgraph [ [1,2], [1] ])


I hope this helps,
    Daan.


>
> Any help would be greatly appreciated.
>
> Regards,
>
> - --
> Eray Ozkural (exa) <[email protected]>
> Comp. Sci. Dept., Bilkent University, Ankara
> www: http://www.cs.bilkent.edu.tr/~erayo
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