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{-# LANGUAGE CPP #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeApplications #-}
module GH117Spec (main, spec) where
import Test.Hspec
#if __GLASGOW_HASKELL__ >= 902
import Data.Constraint
import Data.Constraint.Char
import Data.Proxy
import GHC.TypeLits
spec :: Spec
spec =
describe "GH #117" $ do
it "should evaluate `charToNat @'a'` to 97" $
case charToNat @'a' of
Sub (Dict :: Dict (KnownNat n)) ->
natVal (Proxy @n) `shouldBe` 97
it "should evaluate `natToChar @97` to 'a'" $
case natToChar @97 of
Sub (Dict :: Dict (KnownChar c)) ->
charVal (Proxy @c) `shouldBe` 'a'
#else
spec :: Spec
spec = return ()
#endif
main :: IO ()
main = hspec spec
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