6.8.1. Multi-parameter type classes

MultiParamTypeClasses

Implies:

ConstrainedClassMethods

Implied by:

FunctionalDependencies

Since:

6.8.1

Status:

Included in GHC2024, GHC2021

Allow the definition of typeclasses with more than one parameter.

Multi-parameter type classes are permitted, with extension MultiParamTypeClasses. For example:

class Collection c a where
    union :: c a -> c a -> c a
    ...etc.