Commit 593b7f50 authored by mnislaih's avatar mnislaih
Browse files

Refactoring & documenting the Term pprinter used by :print

parent 9e95b0d6
......@@ -138,10 +138,9 @@ bindSuspensions cms@(Session ref) t = do
-- 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) = cPprTerm (liftM2 (++) cPprShowable cPprTermBase)
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
......@@ -164,7 +163,7 @@ showTerm cms@(Session ref) = cPprTerm cPpr
_ -> 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
......
......@@ -17,6 +17,7 @@ module RtClosureInspect(
pprTerm,
cPprTerm,
cPprTermBase,
CustomTermPrinter,
termType,
foldTerm,
TermFold(..),
......@@ -297,6 +298,7 @@ termTyVars = foldTerm TermFold {
maybe emptyVarEnv tyVarsOfType mb_ty,
fPrim = \ _ _ -> emptyVarEnv }
where concatVarEnv = foldr plusVarEnv emptyVarEnv
----------------------------------
-- Pretty printing of terms
----------------------------------
......@@ -341,12 +343,32 @@ pprTermM1 Suspension{mb_ty=Just ty, bound_to=Just n}
| 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
......@@ -359,7 +381,7 @@ cPprTerm printers_ = go 0 where
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 ->
......
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