import VarSet
import Name
import UniqSupply
-import TcType
+import Type
import GHC
import InteractiveEval
import Outputable
-- A custom Term printer to enable the use of Show instances
showTerm :: Session -> Term -> IO SDoc
-showTerm cms@(Session ref) = cPprTerm cPpr
+showTerm cms@(Session ref) term = do
+ cPprExtended <- cPprTermExtended cms
+ cPprTerm (liftM2 (++) cPprShowable cPprExtended) term
where
- cPpr = \p-> cPprShowable : cPprTermBase p
- cPprShowable prec ty _ val tt =
+ cPprShowable _y = [\prec ty _ val tt ->
if not (all isFullyEvaluatedTerm tt)
then return Nothing
else do
_ -> return Nothing
`finally` do
writeIORef ref hsc_env
- GHC.setSessionDynFlags cms dflags
+ GHC.setSessionDynFlags cms dflags]
needsParens ('"':_) = False -- some simple heuristics to see whether parens
-- are redundant in an arbitrary Show output
needsParens ('(':_) = False
new_ic = ictxt { ic_tmp_ids = id : tmp_ids }
return (hsc_env {hsc_IC = new_ic }, name)
+{- | A custom Term printer to handle some types that
+ we may not want to show, such as Data.Typeable.TypeRep -}
+cPprTermExtended :: Monad m => Session -> IO (CustomTermPrinter m)
+cPprTermExtended session = liftM22 (++) (return cPprTermBase) extended
+ where
+ extended = do
+ [typerep_name] <- parseName session "Data.Typeable.TypeRep"
+ Just (ATyCon typerep) <- lookupName session typerep_name
+
+ return (\_y ->
+ [ ifType (isTyCon typerep) (\_val _prec -> return (text "<typerep>")) ])
+
+ ifType pred f prec ty _ val _tt
+ | pred ty = Just `liftM` f prec val
+ | otherwise = return Nothing
+ isTyCon a_tc ty = fromMaybe False $ do
+ (tc,_) <- splitTyConApp_maybe ty
+ return (a_tc == tc)
+ liftM22 f x y = do x' <- x; y' <- y
+ return$ do x'' <- x';y'' <- y';return (f x'' y'')
+
-- Create new uniques and give them sequentially numbered names
newGrimName :: String -> IO Name
newGrimName userName = do
pprTerm,
cPprTerm,
cPprTermBase,
+ CustomTermPrinter,
termType,
foldTerm,
TermFold(..),
maybe emptyVarEnv tyVarsOfType mb_ty,
fPrim = \ _ _ -> emptyVarEnv }
where concatVarEnv = foldr plusVarEnv emptyVarEnv
+
----------------------------------
-- Pretty printing of terms
----------------------------------
| otherwise = return$ parens$ ppr n <> text "::" <> ppr ty
pprTermM1 _ = panic "pprTermM1"
-type CustomTermPrinter m = Int -> TermProcessor Term (m (Maybe SDoc))
+-------------------------------------------------------
+-- Custom Term Pretty Printers
+-------------------------------------------------------
+
+-- We can want to customize the representation of a
+-- term depending on its type.
+-- However, note that custom printers have to work with
+-- type representations, instead of directly with types.
+-- We cannot use type classes here, unless we employ some
+-- typerep trickery (e.g. Weirich's RepLib tricks),
+-- which I didn't. Therefore, this code replicates a lot
+-- of what type classes provide for free.
+
+-- Concretely a custom term printer takes an explicit
+-- recursion knot, and produces a list of Term Processors,
+-- which additionally need a precedence value to
+-- either produce a SDoc or fail (and they do this in some monad m).
+
+type Precedence = Int
+type RecursionKnot m = Int-> Term -> m SDoc
+type CustomTermPrinter m = RecursionKnot m
+ -> [Precedence -> TermProcessor Term (m (Maybe SDoc))]
-- Takes a list of custom printers with a explicit recursion knot and a term,
-- and returns the output of the first succesful printer, or the default printer
-cPprTerm :: Monad m =>
- ((Int->Term->m SDoc)->[CustomTermPrinter m]) -> Term -> m SDoc
+cPprTerm :: Monad m => CustomTermPrinter m -> Term -> m SDoc
cPprTerm printers_ = go 0 where
printers = printers_ go
go prec t@(Term ty dc val tt) = do
firstJustM [] = return Nothing
-- Default set of custom printers. Note that the recursion knot is explicit
-cPprTermBase :: Monad m => (Int->Term-> m SDoc)->[CustomTermPrinter m]
+cPprTermBase :: Monad m => CustomTermPrinter m
cPprTermBase y =
[
ifTerm isTupleTy (\ _ _ tt ->