Hi all,
What's the recommended way to get hint[0] to play nice with type
synonyms[1]?
A problem occurs with in scope type synonyms involving types not in scope.
I came up with this after looking at the source[2], but it makes me feel
ill:
--8<--
-- hint and type synonyms don't play nice
module Main where
import Language.Haskell.Interpreter
import Data.Typeable as T
import Data.Typeable.Internal
import GHC.Fingerprint.Type
main = failure >> success
test t = (print =<<) . runInterpreter $ do
setImports [ "Prelude" ]
interpret "1/5" t
failure = test (as :: Rational)
-- Left (WontCompile [GhcError {errMsg = "Not in scope: type constructor
or class `Ratio'"}])
success = test (as :: Q)
-- Right (1 % 5)
newtype Q = Q Rational
instance Show Q where
show (Q a) = show a
showsPrec n (Q a) = showsPrec n a
instance Typeable Q where
typeOf _ = TypeRep (Fingerprint 0 0) (T.mkTyCon "Rational") []
--8<--
Thanks,
Claude
[0] http://hackage.haskell.org/package/hint
[1] http://www.haskell.org/onlinereport/decls.html#type-synonym-decls
[2]
http://hackage.haskell.org/packages/archive/hint/0.3.3.4/doc/html/src/Hint-Eval.html#interpret
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