[Haskell-cafe] GHCi and HXT
bonobo at bigpond.net.au
Tue Nov 28 04:38:43 EST 2006
On Tue, 28 Nov 2006 07:43 pm, Daniel McAllansmith wrote:
> On Tuesday 28 November 2006 20:50, Alexis Hazell wrote:
> > i don't understand why i need to specify type signatures when they should
> > already be in scope?
> Is this a result of the monomorphism restriction?
Er . . . . i hadn't heard of this until just now. So i'll have to do some
reading on the matter. :-)
> You need to add a type signature that specifies a specific arrow data type
> 'a' that is an instance of ArrowXml.
Ah! i see - thanks.
> By the way, once you have the declaration of contact in a source file, and
> it is being used by a function in which the ArrowXml instance is not
> ambiguous eg:
> foo = runX contact
> the type checker will be able to infer the type and you don't have to
> include the type signature.
Thanks again for your help. :-)
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