Lemmih wrote:
On Fri, 4 Mar 2005 15:26:52 +0100, Benjamin Franksen <[EMAIL PROTECTED]> wrote:
On Sunday 20 February 2005 14:19, Keean Schupke wrote:
TH has supported multi-parameter classes for a while... new in 6.4 is support for fundeps.
Yes, but unfortunately TH cannot create instances for them which is usually the boilerplate you want to avoid. From Language.Haskell.TH:
data Dec = ... ClassD Cxt Name [Name] [FunDep] [Dec] InstanceD Cxt Type [Dec] ...
Only one 'Type' can be given for an instance.
And there _should_ only be one type. Checkout 'appT'. Some real documentation for TH would clear misconceptions such as this.
Is that really how this is done? That doesn't seem like it can be right:
instance X (a b) -- single parameter class where 'a' has an arrow kind
is very different from:
instance X a b -- multiple parameter class
I would expect a type constructed with 'appT' to correspond to the first declaration, and not to the second.
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