[Haskell-cafe] Instances and multiple inheritance

[MigMit]

I fail to understand why instantiating a four-argument class with five arguments seems obvious to you.

Отправлено с iPhone

Jun 12, 2011, в 12:37, Patrick Browne <patrick.browne at dit.ie> написал(а):

> class (Surfaces v o, Paths a b (v o)) => Vehicles v o a b where
> 
> 
> -- I do not know how to make an instance of Vehicles
> -- What seems to be the *obvious* does not work
> -- instance Vehicles [] Integer (,) Integer Integer  where
> -- Kind error: `Vehicles' is applied to too many type arguments
> -- In the instance declaration for
> --       `Vehicles [] Integer (,) Integer Integer'