Skip to content
Create a gist now

Instantly share code, notes, and snippets.

unsafeCoerce from TypeFamilies and GeneralizedNewtypeDeriving
{-# LANGUAGE TypeFamilies, GeneralizedNewtypeDeriving #-}
type family Switch b a
type instance Switch b (A a) = a
type instance Switch b (B a) = b
newtype A a = A a
newtype B a = B (A a)
deriving (Switchable)
class Switchable a where
switch :: a -> Switch b a
instance Switchable (A a) where
switch (A x) = x
unsafeCoerce :: a -> b
unsafeCoerce x = switch (B (A x))
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Something went wrong with that request. Please try again.