-- The above warning supression flag is a temporary kludge.
-- While working on this module you are encouraged to remove it and fix
-- any warnings in the module. See
--- http://hackage.haskell.org/trac/ghc/wiki/CodingStyle#Warnings
+-- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
-- for details
module TcEnv(
data InstBindings
= VanillaInst -- The normal case
- (LHsBinds Name) -- Bindings
+ (LHsBinds Name) -- Bindings for the instance methods
[LSig Name] -- User pragmas recorded for generating
-- specialised instances
| NewTypeDerived -- Used for deriving instances of newtypes, where the
-- witness dictionary is identical to the argument
-- dictionary. Hence no bindings, no pragmas.
- (Maybe [PredType])
- -- Nothing => The newtype-derived instance involves type variables,
- -- and the dfun has a type like df :: forall a. Eq a => Eq (T a)
- -- Just (r:scs) => The newtype-defined instance has no type variables
- -- so the dfun is just a constant, df :: Eq T
- -- In this case we need to know waht the rep dict, r, and the
- -- superclasses, scs, are. (In the Nothing case these are in the
- -- dict fun's type.)
- -- Invariant: these PredTypes have no free variables
- -- NB: In both cases, the representation dict is the *first* dict.
pprInstInfo info = vcat [ptext SLIT("InstInfo:") <+> ppr (idType (iDFunId info))]
pprInstInfoDetails info = pprInstInfo info $$ nest 2 (details (iBinds info))
where
- details (VanillaInst b _) = pprLHsBinds b
- details (NewTypeDerived _) = text "Derived from the representation type"
+ details (VanillaInst b _) = pprLHsBinds b
+ details NewTypeDerived = text "Derived from the representation type"
simpleInstInfoClsTy :: InstInfo -> (Class, Type)
simpleInstInfoClsTy info = case instanceHead (iSpec info) of