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|
{-# LANGUAGE TypeFamilies #-}
module Types where
data Quux = Bar | Baz
newtype Foo = Foo ()
type FooQuux = (Foo, Quux)
type QuuxFoo = (Quux, Foo)
data family Norf a b
data instance Norf Foo Quux = NFQ Foo Quux
data instance Norf Quux Foo = NQF Quux Foo
type family Norf' a b
type instance Norf' Foo Quux = (Foo, Quux)
type instance Norf' Quux Foo = (Quux, Foo)
norf1 :: Norf Foo Quux -> Int
norf1 (NFQ (Foo ()) Bar) = 0
norf1 (NFQ (Foo ()) Baz) = 1
norf2 :: Norf Quux Foo -> Int
norf2 (NQF Bar (Foo ())) = 0
norf2 (NQF Baz (Foo ())) = 1
norf1' :: Norf' Foo Quux -> Int
norf1' (Foo (), Bar) = 0
norf1' (Foo (), Baz) = 1
norf2' :: Norf' Quux Foo -> Int
norf2' (Bar, Foo ()) = 0
norf2' (Baz, Foo ()) = 1
|
