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.
*nod* Thanks again for your help. :-) Alexis.