%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[DsMonad]{@DsMonad@: monadery used in desugaring}
\begin{code}
-#include "HsVersions.h"
-
module DsMonad (
- DsM(..),
- initDs, returnDs, thenDs, andDs, mapDs, listDs,
- mapAndUnzipDs, zipWithDs,
- uniqSMtoDsM,
- newTyVarsDs, cloneTyVarsDs,
- duplicateLocalDs, newSysLocalDs, newSysLocalsDs,
+ DsM, mappM,
+ initDs, returnDs, thenDs, listDs, fixDs, mapAndUnzipDs, foldlDs,
+
+ newTyVarsDs,
+ duplicateLocalDs, newSysLocalDs, newSysLocalsDs, newUniqueId,
newFailLocalDs,
- getSrcLocDs, putSrcLocDs,
- getModuleAndGroupDs,
- extendEnvDs, lookupEnvDs, lookupEnvWithDefaultDs,
- DsIdEnv(..),
- lookupId,
-
- dsShadowError,
- DsMatchContext(..), DsMatchKind(..), pprDsWarnings
+ getSrcSpanDs, putSrcSpanDs,
+ getModuleDs,
+ newUnique,
+ UniqSupply, newUniqueSupply,
+ getDOptsDs,
+ dsLookupGlobal, dsLookupGlobalId, dsLookupTyCon, dsLookupDataCon,
+
+ DsMetaEnv, DsMetaVal(..), dsLookupMetaEnv, dsExtendMetaEnv,
+
+ -- Warnings
+ DsWarning, dsWarn,
+
+ -- Data types
+ DsMatchContext(..),
+ EquationInfo(..), MatchResult(..), DsWrapper, idWrapper,
+ CanItFail(..), orFail
) where
-IMP_Ubiq()
-
-import Bag ( emptyBag, snocBag, bagToList )
-import CmdLineOpts ( opt_SccGroup )
-import CoreSyn ( SYN_IE(CoreExpr) )
-import CoreUtils ( substCoreExpr )
-import HsSyn ( OutPat )
-import Id ( mkSysLocal, mkIdWithNewUniq,
- lookupIdEnv, growIdEnvList, GenId, SYN_IE(IdEnv)
- )
-import PprType ( GenType, GenTyVar )
-import PprStyle ( PprStyle(..) )
-import Pretty
-import SrcLoc ( unpackSrcLoc, mkUnknownSrcLoc, SrcLoc )
-import TcHsSyn ( TypecheckedPat(..) )
-import TyVar ( nullTyVarEnv, cloneTyVar, GenTyVar{-instance Eq-} )
-import Unique ( Unique{-instances-} )
-import UniqSupply ( splitUniqSupply, getUnique, getUniques,
- mapUs, thenUs, returnUs, SYN_IE(UniqSM) )
-import Util ( assoc, mapAccumL, zipWithEqual, panic )
+#include "HsVersions.h"
+
+import TcRnMonad
+import CoreSyn ( CoreExpr )
+import HsSyn ( HsExpr, HsMatchContext, Pat )
+import TcIface ( tcIfaceGlobal )
+import RdrName ( GlobalRdrEnv )
+import HscTypes ( TyThing(..), TypeEnv, HscEnv,
+ tyThingId, tyThingTyCon, tyThingDataCon, unQualInScope )
+import Bag ( emptyBag, snocBag, Bag )
+import DataCon ( DataCon )
+import TyCon ( TyCon )
+import DataCon ( DataCon )
+import Id ( mkSysLocal, setIdUnique, Id )
+import Module ( Module )
+import Var ( TyVar, setTyVarUnique )
+import Outputable
+import SrcLoc ( noSrcSpan, SrcSpan )
+import Type ( Type )
+import UniqSupply ( UniqSupply, uniqsFromSupply )
+import Name ( Name, nameOccName )
+import NameEnv
+import OccName ( occNameFS )
+import CmdLineOpts ( DynFlags )
+import ErrUtils ( WarnMsg, mkWarnMsg )
+import Bag ( mapBag )
+
+import DATA_IOREF ( newIORef, readIORef )
infixr 9 `thenDs`
\end{code}
+%************************************************************************
+%* *
+ Data types for the desugarer
+%* *
+%************************************************************************
+
+\begin{code}
+data DsMatchContext
+ = DsMatchContext (HsMatchContext Name) [Pat Id] SrcSpan
+ | NoMatchContext
+ deriving ()
+
+data EquationInfo
+ = EqnInfo { eqn_wrap :: DsWrapper, -- Bindings
+ eqn_pats :: [Pat Id], -- The patterns for an eqn
+ eqn_rhs :: MatchResult } -- What to do after match
+
+type DsWrapper = CoreExpr -> CoreExpr
+idWrapper e = e
+
+-- The semantics of (match vs (EqnInfo wrap pats rhs)) is the MatchResult
+-- \fail. wrap (case vs of { pats -> rhs fail })
+-- where vs are not in the domain of wrap
+
+
+-- A MatchResult is an expression with a hole in it
+data MatchResult
+ = MatchResult
+ CanItFail -- Tells whether the failure expression is used
+ (CoreExpr -> DsM CoreExpr)
+ -- Takes a expression to plug in at the
+ -- failure point(s). The expression should
+ -- be duplicatable!
+
+data CanItFail = CanFail | CantFail
+
+orFail CantFail CantFail = CantFail
+orFail _ _ = CanFail
+\end{code}
+
+
+%************************************************************************
+%* *
+ Monad stuff
+%* *
+%************************************************************************
+
Now the mondo monad magic (yes, @DsM@ is a silly name)---carry around
a @UniqueSupply@ and some annotations, which
presumably include source-file location information:
\begin{code}
-type DsM result =
- UniqSupply
- -> SrcLoc -- to put in pattern-matching error msgs
- -> (FAST_STRING, FAST_STRING) -- "module"+"group" : for SCC profiling
- -> DsIdEnv
- -> DsWarnings
- -> (result, DsWarnings)
-
-type DsWarnings = Bag DsMatchContext -- The desugarer reports matches which are
- -- completely shadowed
-{-# INLINE andDs #-}
-{-# INLINE thenDs #-}
-{-# INLINE returnDs #-}
+type DsM result = TcRnIf DsGblEnv DsLclEnv result
+
+-- Compatibility functions
+fixDs = fixM
+thenDs = thenM
+returnDs = returnM
+listDs = sequenceM
+foldlDs = foldlM
+mapAndUnzipDs = mapAndUnzipM
+
+
+type DsWarning = (SrcSpan, SDoc)
+ -- Not quite the same as a WarnMsg, we have an SDoc here
+ -- and we'll do the print_unqual stuff later on to turn it
+ -- into a Doc.
+
+data DsGblEnv = DsGblEnv {
+ ds_mod :: Module, -- For SCC profiling
+ ds_warns :: IORef (Bag DsWarning), -- Warning messages
+ ds_if_env :: (IfGblEnv, IfLclEnv) -- Used for looking up global,
+ -- possibly-imported things
+ }
+
+data DsLclEnv = DsLclEnv {
+ ds_meta :: DsMetaEnv, -- Template Haskell bindings
+ ds_loc :: SrcSpan -- to put in pattern-matching error msgs
+ }
+
+-- Inside [| |] brackets, the desugarer looks
+-- up variables in the DsMetaEnv
+type DsMetaEnv = NameEnv DsMetaVal
+
+data DsMetaVal
+ = Bound Id -- Bound by a pattern inside the [| |].
+ -- Will be dynamically alpha renamed.
+ -- The Id has type THSyntax.Var
+
+ | Splice (HsExpr Id) -- These bindings are introduced by
+ -- the PendingSplices on a HsBracketOut
-- initDs returns the UniqSupply out the end (not just the result)
-initDs :: UniqSupply
- -> DsIdEnv
- -> FAST_STRING -- module name: for profiling; (group name: from switches)
+initDs :: HscEnv
+ -> Module -> GlobalRdrEnv -> TypeEnv
-> DsM a
- -> (a, DsWarnings)
-
-initDs init_us env mod_name action
- = action init_us mkUnknownSrcLoc module_and_group env emptyBag
- where
- module_and_group = (mod_name, grp_name)
- grp_name = case opt_SccGroup of
- Just xx -> _PK_ xx
- Nothing -> mod_name -- default: module name
-
-thenDs :: DsM a -> (a -> DsM b) -> DsM b
-andDs :: (a -> a -> a) -> DsM a -> DsM a -> DsM a
-
-thenDs m1 m2 us loc mod_and_grp env warns
- = case splitUniqSupply us of { (s1, s2) ->
- case (m1 s1 loc mod_and_grp env warns) of { (result, warns1) ->
- m2 result s2 loc mod_and_grp env warns1}}
-
-andDs combiner m1 m2 us loc mod_and_grp env warns
- = case splitUniqSupply us of { (s1, s2) ->
- case (m1 s1 loc mod_and_grp env warns) of { (result1, warns1) ->
- case (m2 s2 loc mod_and_grp env warns1) of { (result2, warns2) ->
- (combiner result1 result2, warns2) }}}
-
-returnDs :: a -> DsM a
-returnDs result us loc mod_and_grp env warns = (result, warns)
-
-listDs :: [DsM a] -> DsM [a]
-listDs [] = returnDs []
-listDs (x:xs)
- = x `thenDs` \ r ->
- listDs xs `thenDs` \ rs ->
- returnDs (r:rs)
-
-mapDs :: (a -> DsM b) -> [a] -> DsM [b]
-
-mapDs f [] = returnDs []
-mapDs f (x:xs)
- = f x `thenDs` \ r ->
- mapDs f xs `thenDs` \ rs ->
- returnDs (r:rs)
-
-mapAndUnzipDs :: (a -> DsM (b, c)) -> [a] -> DsM ([b], [c])
-
-mapAndUnzipDs f [] = returnDs ([], [])
-mapAndUnzipDs f (x:xs)
- = f x `thenDs` \ (r1, r2) ->
- mapAndUnzipDs f xs `thenDs` \ (rs1, rs2) ->
- returnDs (r1:rs1, r2:rs2)
-
-zipWithDs :: (a -> b -> DsM c) -> [a] -> [b] -> DsM [c]
-
-zipWithDs f [] [] = returnDs []
-zipWithDs f (x:xs) (y:ys)
- = f x y `thenDs` \ r ->
- zipWithDs f xs ys `thenDs` \ rs ->
- returnDs (r:rs)
--- Note: crashes if lists not equal length (like zipWithEqual)
+ -> IO (a, Bag WarnMsg)
+
+initDs hsc_env mod rdr_env type_env thing_inside
+ = do { warn_var <- newIORef emptyBag
+ ; let { if_genv = IfGblEnv { if_rec_types = Just (mod, return type_env) }
+ ; if_lenv = mkIfLclEnv mod (ptext SLIT("GHC error in desugarer lookup in") <+> ppr mod)
+ ; gbl_env = DsGblEnv { ds_mod = mod,
+ ds_if_env = (if_genv, if_lenv),
+ ds_warns = warn_var }
+ ; lcl_env = DsLclEnv { ds_meta = emptyNameEnv,
+ ds_loc = noSrcSpan } }
+
+ ; res <- initTcRnIf 'd' hsc_env gbl_env lcl_env thing_inside
+
+ ; warns <- readIORef warn_var
+ ; return (res, mapBag mk_warn warns)
+ }
+ where
+ print_unqual = unQualInScope rdr_env
+
+ mk_warn :: (SrcSpan,SDoc) -> WarnMsg
+ mk_warn (loc,sdoc) = mkWarnMsg loc print_unqual sdoc
\end{code}
+%************************************************************************
+%* *
+ Operations in the monad
+%* *
+%************************************************************************
+
And all this mysterious stuff is so we can occasionally reach out and
grab one or more names. @newLocalDs@ isn't exported---exported
functions are defined with it. The difference in name-strings makes
it easier to read debugging output.
-\begin{code}
-newLocalDs :: FAST_STRING -> Type -> DsM Id
-newLocalDs nm ty us loc mod_and_grp env warns
- = case (getUnique us) of { assigned_uniq ->
- (mkSysLocal nm assigned_uniq ty loc, warns) }
-newSysLocalDs = newLocalDs SLIT("ds")
-newSysLocalsDs tys = mapDs (newLocalDs SLIT("ds")) tys
-newFailLocalDs = newLocalDs SLIT("fail")
+\begin{code}
+-- Make a new Id with the same print name, but different type, and new unique
+newUniqueId :: Name -> Type -> DsM Id
+newUniqueId id ty
+ = newUnique `thenDs` \ uniq ->
+ returnDs (mkSysLocal (occNameFS (nameOccName id)) uniq ty)
duplicateLocalDs :: Id -> DsM Id
-duplicateLocalDs old_local us loc mod_and_grp env warns
- = case (getUnique us) of { assigned_uniq ->
- (mkIdWithNewUniq old_local assigned_uniq, warns) }
-
-cloneTyVarsDs :: [TyVar] -> DsM [TyVar]
-cloneTyVarsDs tyvars us loc mod_and_grp env warns
- = case (getUniques (length tyvars) us) of { uniqs ->
- (zipWithEqual "cloneTyVarsDs" cloneTyVar tyvars uniqs, warns) }
+duplicateLocalDs old_local
+ = newUnique `thenDs` \ uniq ->
+ returnDs (setIdUnique old_local uniq)
+
+newSysLocalDs, newFailLocalDs :: Type -> DsM Id
+newSysLocalDs ty
+ = newUnique `thenDs` \ uniq ->
+ returnDs (mkSysLocal FSLIT("ds") uniq ty)
+
+newSysLocalsDs tys = mappM newSysLocalDs tys
+
+newFailLocalDs ty
+ = newUnique `thenDs` \ uniq ->
+ returnDs (mkSysLocal FSLIT("fail") uniq ty)
+ -- The UserLocal bit just helps make the code a little clearer
\end{code}
\begin{code}
newTyVarsDs :: [TyVar] -> DsM [TyVar]
-
-newTyVarsDs tyvar_tmpls us loc mod_and_grp env warns
- = case (getUniques (length tyvar_tmpls) us) of { uniqs ->
- (zipWithEqual "newTyVarsDs" cloneTyVar tyvar_tmpls uniqs, warns) }
+newTyVarsDs tyvar_tmpls
+ = newUniqueSupply `thenDs` \ uniqs ->
+ returnDs (zipWith setTyVarUnique tyvar_tmpls (uniqsFromSupply uniqs))
\end{code}
We can also reach out and either set/grab location information from
-the @SrcLoc@ being carried around.
+the @SrcSpan@ being carried around.
+
\begin{code}
-uniqSMtoDsM :: UniqSM a -> DsM a
+getDOptsDs :: DsM DynFlags
+getDOptsDs = getDOpts
-uniqSMtoDsM u_action us loc mod_and_grp env warns
- = (u_action us, warns)
+getModuleDs :: DsM Module
+getModuleDs = do { env <- getGblEnv; return (ds_mod env) }
-getSrcLocDs :: DsM (String, String)
-getSrcLocDs us loc mod_and_grp env warns
- = case (unpackSrcLoc loc) of { (x,y) ->
- ((_UNPK_ x, _UNPK_ y), warns) }
+getSrcSpanDs :: DsM SrcSpan
+getSrcSpanDs = do { env <- getLclEnv; return (ds_loc env) }
-putSrcLocDs :: SrcLoc -> DsM a -> DsM a
-putSrcLocDs new_loc expr us old_loc mod_and_grp env warns
- = expr us new_loc mod_and_grp env warns
+putSrcSpanDs :: SrcSpan -> DsM a -> DsM a
+putSrcSpanDs new_loc thing_inside = updLclEnv (\ env -> env {ds_loc = new_loc}) thing_inside
-dsShadowError :: DsMatchContext -> DsM ()
-dsShadowError cxt us loc mod_and_grp env warns
- = ((), warns `snocBag` cxt)
+dsWarn :: DsWarning -> DsM ()
+dsWarn (loc,warn) = do { env <- getGblEnv; updMutVar (ds_warns env) (`snocBag` (loc,msg)) }
+ where
+ msg = ptext SLIT("Warning:") <+> warn
\end{code}
\begin{code}
-getModuleAndGroupDs :: DsM (FAST_STRING, FAST_STRING)
-getModuleAndGroupDs us loc mod_and_grp env warns
- = (mod_and_grp, warns)
+dsLookupGlobal :: Name -> DsM TyThing
+-- Very like TcEnv.tcLookupGlobal
+dsLookupGlobal name
+ = do { env <- getGblEnv
+ ; setEnvs (ds_if_env env)
+ (tcIfaceGlobal name) }
+
+dsLookupGlobalId :: Name -> DsM Id
+dsLookupGlobalId name
+ = dsLookupGlobal name `thenDs` \ thing ->
+ returnDs (tyThingId thing)
+
+dsLookupTyCon :: Name -> DsM TyCon
+dsLookupTyCon name
+ = dsLookupGlobal name `thenDs` \ thing ->
+ returnDs (tyThingTyCon thing)
+
+dsLookupDataCon :: Name -> DsM DataCon
+dsLookupDataCon name
+ = dsLookupGlobal name `thenDs` \ thing ->
+ returnDs (tyThingDataCon thing)
\end{code}
\begin{code}
-type DsIdEnv = IdEnv CoreExpr
-
-extendEnvDs :: [(Id, CoreExpr)] -> DsM a -> DsM a
+dsLookupMetaEnv :: Name -> DsM (Maybe DsMetaVal)
+dsLookupMetaEnv name = do { env <- getLclEnv; return (lookupNameEnv (ds_meta env) name) }
-extendEnvDs pairs then_do us loc mod_and_grp old_env warns
- = case splitUniqSupply us of { (s1, s2) ->
- let
- revised_pairs = subst_all pairs s1
- in
- then_do s2 loc mod_and_grp (growIdEnvList old_env revised_pairs) warns
- }
- where
- subst_all pairs = mapUs subst pairs
-
- subst (v, expr)
- = substCoreExpr old_env nullTyVarEnv expr `thenUs` \ new_expr ->
- returnUs (v, new_expr)
-
-lookupEnvDs :: Id -> DsM (Maybe CoreExpr)
-lookupEnvDs id us loc mod_and_grp env warns
- = (lookupIdEnv env id, warns)
- -- Note: we don't assert anything about the Id
- -- being looked up. There's not really anything
- -- much to say about it. (WDP 94/06)
-
-lookupEnvWithDefaultDs :: Id -> CoreExpr -> DsM CoreExpr
-lookupEnvWithDefaultDs id deflt us loc mod_and_grp env warns
- = (case (lookupIdEnv env id) of
- Nothing -> deflt
- Just xx -> xx,
- warns)
-
-lookupId :: [(Id, a)] -> Id -> a
-lookupId env id
- = assoc "lookupId" env id
+dsExtendMetaEnv :: DsMetaEnv -> DsM a -> DsM a
+dsExtendMetaEnv menv thing_inside
+ = updLclEnv (\env -> env { ds_meta = ds_meta env `plusNameEnv` menv }) thing_inside
\end{code}
-%************************************************************************
-%* *
-%* type synonym EquationInfo and access functions for its pieces *
-%* *
-%************************************************************************
-
-\begin{code}
-data DsMatchContext
- = DsMatchContext DsMatchKind [TypecheckedPat] SrcLoc
- | NoMatchContext
-data DsMatchKind
- = FunMatch Id
- | CaseMatch
- | LambdaMatch
- | PatBindMatch
- | DoBindMatch
-
-pprDsWarnings :: PprStyle -> Bag DsMatchContext -> Pretty
-pprDsWarnings sty warns
- = ppAboves (map pp_cxt (bagToList warns))
- where
- pp_cxt NoMatchContext = ppPStr SLIT("Some match is shadowed; I don't know what")
- pp_cxt (DsMatchContext kind pats loc)
- = ppHang (ppBesides [ppr PprForUser loc, ppPStr SLIT(": ")])
- 4 (ppHang (ppPStr SLIT("Pattern match(es) completely overlapped:"))
- 4 (pp_match kind pats))
-
- pp_match (FunMatch fun) pats
- = ppHang (ppr sty fun)
- 4 (ppSep [ppSep (map (ppr sty) pats), ppPStr SLIT("= ...")])
-
- pp_match CaseMatch pats
- = ppHang (ppPStr SLIT("in a case alternative:"))
- 4 (ppSep [ppSep (map (ppr sty) pats), pp_arrow_dotdotdot])
-
- pp_match PatBindMatch pats
- = ppHang (ppPStr SLIT("in a pattern binding:"))
- 4 (ppSep [ppSep (map (ppr sty) pats), pp_arrow_dotdotdot])
-
- pp_match LambdaMatch pats
- = ppHang (ppPStr SLIT("in a lambda abstraction:"))
- 4 (ppSep [ppSep (map (ppr sty) pats), pp_arrow_dotdotdot])
-
- pp_match DoBindMatch pats
- = ppHang (ppPStr SLIT("in a `do' pattern binding:"))
- 4 (ppSep [ppSep (map (ppr sty) pats), pp_arrow_dotdotdot])
-
- pp_arrow_dotdotdot = ppPStr SLIT("-> ...")
-\end{code}
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