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{-# LANGUAGE TemplateHaskell, FlexibleInstances,
MultiParamTypeClasses, TypeSynonymInstances #-}
module Main where
import Language.Haskell.TH
import Language.Haskell.TH.Syntax
class Eq a => MyClass a
data Foo = Foo deriving Eq
instance MyClass Foo
data Bar = Bar
deriving Eq
type Baz = Bar
instance MyClass Baz
data Quux a = Quux a deriving Eq
data Quux2 a = Quux2 a deriving Eq
instance Eq a => MyClass (Quux a)
instance Num a => MyClass (Quux2 a)
class MyClass2 a b
instance MyClass2 Int Bool
main = do
putStrLn $(do { info <- reify ''MyClass; lift (pprint info) })
print $(isClassInstance ''Eq [ConT ''Foo] >>= lift)
print $(isClassInstance ''MyClass [ConT ''Foo] >>= lift)
print $ not $(isClassInstance ''Show [ConT ''Foo] >>= lift)
print $(isClassInstance ''MyClass [ConT ''Bar] >>= lift) -- this one
print $(isClassInstance ''MyClass [ConT ''Baz] >>= lift)
print $(isClassInstance ''MyClass [AppT (ConT ''Quux) (ConT ''Int)] >>= lift) --this one
print $(isClassInstance ''MyClass [AppT (ConT ''Quux2) (ConT ''Int)] >>= lift) -- this one
print $(isClassInstance ''MyClass2 [ConT ''Int, ConT ''Bool] >>= lift)
print $(isClassInstance ''MyClass2 [ConT ''Bool, ConT ''Bool] >>= lift)
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