ghc-prim-0.10.0: GHC primitives

GHC.Magic.Dict

Description

Defines the withDict function. For more information, see Note [withDict] in GHC.Tc.Instance.Class in GHC. The definition of withDict is located in a separate module from GHC.Magic because withDict is Unsafe (it threatens type class coherence) while GHC.Magic is Trustworthy.

Use GHC.Exts from the base package instead of importing this module directly.

Synopsis

# Documentation

class WithDict cls meth where Source #

withDict d f provides a way to call a type-class–overloaded function f by applying it to the supplied dictionary d.

withDict can only be used if the type class has a single method with no superclasses. For more (important) details on how this works, see Note [withDict] in GHC.Tc.Instance.Class in GHC.

Methods

withDict :: forall {rr :: RuntimeRep} (r :: TYPE rr). meth -> (cls => r) -> r Source #