\begin{code}
module TcMatches ( tcMatchesFun, tcGRHSsPat, tcMatchesCase, tcMatchLambda,
- matchCtxt, TcMatchCtxt(..),
- tcStmts, tcDoStmts, tcBody,
+ TcMatchCtxt(..),
+ tcStmts, tcStmtsAndThen, tcDoStmts, tcBody,
tcDoStmt, tcMDoStmt, tcGuardStmt
) where
-#include "HsVersions.h"
-
-import {-# SOURCE #-} TcExpr( tcSyntaxOp, tcInferRho, tcMonoExpr, tcPolyExpr )
+import {-# SOURCE #-} TcExpr( tcSyntaxOp, tcInferRhoNC, tcCheckId,
+ tcMonoExpr, tcMonoExprNC, tcPolyExpr )
import HsSyn
+import BasicTypes
import TcRnMonad
-import TcGadt
-import Inst
import TcEnv
import TcPat
import TcMType
import TcType
import TcBinds
import TcUnify
-import TcSimplify
import Name
import TysWiredIn
-import PrelNames
import Id
import TyCon
+import TysPrim
+import Coercion ( mkSymCoI )
import Outputable
+import Util
import SrcLoc
+import FastString
+
+-- Create chunkified tuple tybes for monad comprehensions
+import MkCore
+
+import Control.Monad
+
+#include "HsVersions.h"
\end{code}
%************************************************************************
is used in error messages. It checks that all the equations have the
same number of arguments before using @tcMatches@ to do the work.
+Note [Polymorphic expected type for tcMatchesFun]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+tcMatchesFun may be given a *sigma* (polymorphic) type
+so it must be prepared to use tcGen to skolemise it.
+See Note [sig_tau may be polymorphic] in TcPat.
+
\begin{code}
-tcMatchesFun :: Name
+tcMatchesFun :: Name -> Bool
-> MatchGroup Name
- -> BoxyRhoType -- Expected type of function
- -> TcM (HsWrapper, MatchGroup TcId) -- Returns type of body
-
-tcMatchesFun fun_name matches exp_ty
+ -> TcSigmaType -- Expected type of function
+ -> TcM (HsWrapper, MatchGroup TcId) -- Returns type of body
+tcMatchesFun fun_name inf matches exp_ty
= do { -- Check that they all have the same no of arguments
-- Location is in the monad, set the caller so that
-- any inter-equation error messages get some vaguely
-- sensible location. Note: we have to do this odd
-- ann-grabbing, because we don't always have annotations in
-- hand when we call tcMatchesFun...
- checkArgs fun_name matches
-
- -- ToDo: Don't use "expected" stuff if there ain't a type signature
- -- because inconsistency between branches
- -- may show up as something wrong with the (non-existent) type signature
-
- -- This is one of two places places we call subFunTys
- -- The point is that if expected_y is a "hole", we want
- -- to make pat_tys and rhs_ty as "holes" too.
- ; subFunTys doc n_pats exp_ty $ \ pat_tys rhs_ty ->
- tcMatches match_ctxt pat_tys rhs_ty matches
- }
+ traceTc "tcMatchesFun" (ppr fun_name $$ ppr exp_ty)
+ ; checkArgs fun_name matches
+
+ ; (wrap_gen, (wrap_fun, group))
+ <- tcGen (FunSigCtxt fun_name) exp_ty $ \ _ exp_rho ->
+ -- Note [Polymorphic expected type for tcMatchesFun]
+ matchFunTys herald arity exp_rho $ \ pat_tys rhs_ty ->
+ tcMatches match_ctxt pat_tys rhs_ty matches
+ ; return (wrap_gen <.> wrap_fun, group) }
where
- doc = ptext SLIT("The equation(s) for") <+> quotes (ppr fun_name)
- <+> ptext SLIT("have") <+> speakNOf n_pats (ptext SLIT("argument"))
- n_pats = matchGroupArity matches
- match_ctxt = MC { mc_what = FunRhs fun_name, mc_body = tcBody }
+ arity = matchGroupArity matches
+ herald = ptext (sLit "The equation(s) for")
+ <+> quotes (ppr fun_name) <+> ptext (sLit "have")
+ match_ctxt = MC { mc_what = FunRhs fun_name inf, mc_body = tcBody }
\end{code}
@tcMatchesCase@ doesn't do the argument-count check because the
tcMatchesCase :: TcMatchCtxt -- Case context
-> TcRhoType -- Type of scrutinee
-> MatchGroup Name -- The case alternatives
- -> BoxyRhoType -- Type of whole case expressions
+ -> TcRhoType -- Type of whole case expressions
-> TcM (MatchGroup TcId) -- Translated alternatives
tcMatchesCase ctxt scrut_ty matches res_ty
+ | isEmptyMatchGroup matches -- Allow empty case expressions
+ = return (MatchGroup [] (mkFunTys [scrut_ty] res_ty))
+
+ | otherwise
= tcMatches ctxt [scrut_ty] res_ty matches
-tcMatchLambda :: MatchGroup Name -> BoxyRhoType -> TcM (HsWrapper, MatchGroup TcId)
+tcMatchLambda :: MatchGroup Name -> TcRhoType -> TcM (HsWrapper, MatchGroup TcId)
tcMatchLambda match res_ty
- = subFunTys doc n_pats res_ty $ \ pat_tys rhs_ty ->
+ = matchFunTys herald n_pats res_ty $ \ pat_tys rhs_ty ->
tcMatches match_ctxt pat_tys rhs_ty match
where
n_pats = matchGroupArity match
- doc = sep [ ptext SLIT("The lambda expression")
- <+> quotes (pprSetDepth 1 $ pprMatches LambdaExpr match),
+ herald = sep [ ptext (sLit "The lambda expression")
+ <+> quotes (pprSetDepth (PartWay 1) $
+ pprMatches (LambdaExpr :: HsMatchContext Name) match),
-- The pprSetDepth makes the abstraction print briefly
- ptext SLIT("has") <+> speakNOf n_pats (ptext SLIT("argument"))]
+ ptext (sLit "has")]
match_ctxt = MC { mc_what = LambdaExpr,
mc_body = tcBody }
\end{code}
@tcGRHSsPat@ typechecks @[GRHSs]@ that occur in a @PatMonoBind@.
\begin{code}
-tcGRHSsPat :: GRHSs Name -> BoxyRhoType -> TcM (GRHSs TcId)
+tcGRHSsPat :: GRHSs Name -> TcRhoType -> TcM (GRHSs TcId)
-- Used for pattern bindings
-tcGRHSsPat grhss res_ty = tcGRHSs match_ctxt grhss (emptyRefinement, res_ty)
- -- emptyRefinement: no refinement in a pattern binding
+tcGRHSsPat grhss res_ty = tcGRHSs match_ctxt grhss res_ty
where
match_ctxt = MC { mc_what = PatBindRhs,
mc_body = tcBody }
\end{code}
+\begin{code}
+matchFunTys
+ :: SDoc -- See Note [Herald for matchExpecteFunTys] in TcUnify
+ -> Arity
+ -> TcRhoType
+ -> ([TcSigmaType] -> TcRhoType -> TcM a)
+ -> TcM (HsWrapper, a)
+
+-- Written in CPS style for historical reasons;
+-- could probably be un-CPSd, like matchExpectedTyConApp
+
+matchFunTys herald arity res_ty thing_inside
+ = do { (coi, pat_tys, res_ty) <- matchExpectedFunTys herald arity res_ty
+ ; res <- thing_inside pat_tys res_ty
+ ; return (coiToHsWrapper (mkSymCoI coi), res) }
+\end{code}
+
%************************************************************************
%* *
\subsection{tcMatch}
\begin{code}
tcMatches :: TcMatchCtxt
- -> [BoxySigmaType] -- Expected pattern types
- -> BoxyRhoType -- Expected result-type of the Match.
+ -> [TcSigmaType] -- Expected pattern types
+ -> TcRhoType -- Expected result-type of the Match.
-> MatchGroup Name
-> TcM (MatchGroup TcId)
data TcMatchCtxt -- c.f. TcStmtCtxt, also in this module
= MC { mc_what :: HsMatchContext Name, -- What kind of thing this is
- mc_body :: LHsExpr Name -- Type checker for a body of an alternative
- -> (Refinement, BoxyRhoType)
+ mc_body :: LHsExpr Name -- Type checker for a body of
+ -- an alternative
+ -> TcRhoType
-> TcM (LHsExpr TcId) }
tcMatches ctxt pat_tys rhs_ty (MatchGroup matches _)
- = do { matches' <- mapM (tcMatch ctxt pat_tys rhs_ty) matches
+ = ASSERT( not (null matches) ) -- Ensure that rhs_ty is filled in
+ do { matches' <- mapM (tcMatch ctxt pat_tys rhs_ty) matches
; return (MatchGroup matches' (mkFunTys pat_tys rhs_ty)) }
-------------
tcMatch :: TcMatchCtxt
- -> [BoxySigmaType] -- Expected pattern types
- -> BoxyRhoType -- Expected result-type of the Match.
+ -> [TcSigmaType] -- Expected pattern types
+ -> TcRhoType -- Expected result-type of the Match.
-> LMatch Name
-> TcM (LMatch TcId)
= wrapLocM (tc_match ctxt pat_tys rhs_ty) match
where
tc_match ctxt pat_tys rhs_ty match@(Match pats maybe_rhs_sig grhss)
- = addErrCtxt (matchCtxt (mc_what ctxt) match) $
- do { (pats', grhss') <- tcLamPats pats pat_tys rhs_ty $
- tc_grhss ctxt maybe_rhs_sig grhss
+ = add_match_ctxt match $
+ do { (pats', grhss') <- tcPats (mc_what ctxt) pats pat_tys $
+ tc_grhss ctxt maybe_rhs_sig grhss rhs_ty
; return (Match pats' Nothing grhss') }
tc_grhss ctxt Nothing grhss rhs_ty
= tcGRHSs ctxt grhss rhs_ty -- No result signature
-- Result type sigs are no longer supported
- tc_grhss ctxt (Just res_sig) grhss (co, rhs_ty)
- = do { addErr (ptext SLIT("Ignoring (deprecated) result type signature")
- <+> ppr res_sig)
- ; tcGRHSs ctxt grhss (co, rhs_ty) }
+ tc_grhss _ (Just {}) _ _
+ = panic "tc_ghrss" -- Rejected by renamer
+
+ -- For (\x -> e), tcExpr has already said "In the expresssion \x->e"
+ -- so we don't want to add "In the lambda abstraction \x->e"
+ add_match_ctxt match thing_inside
+ = case mc_what ctxt of
+ LambdaExpr -> thing_inside
+ m_ctxt -> addErrCtxt (pprMatchInCtxt m_ctxt match) thing_inside
-------------
-tcGRHSs :: TcMatchCtxt -> GRHSs Name -> (Refinement, BoxyRhoType)
+tcGRHSs :: TcMatchCtxt -> GRHSs Name -> TcRhoType
-> TcM (GRHSs TcId)
-- Notice that we pass in the full res_ty, so that we get
tcGRHSs ctxt (GRHSs grhss binds) res_ty
= do { (binds', grhss') <- tcLocalBinds binds $
- mappM (wrapLocM (tcGRHS ctxt res_ty)) grhss
+ mapM (wrapLocM (tcGRHS ctxt res_ty)) grhss
- ; returnM (GRHSs grhss' binds') }
+ ; return (GRHSs grhss' binds') }
-------------
-tcGRHS :: TcMatchCtxt -> (Refinement, BoxyRhoType) -> GRHS Name -> TcM (GRHS TcId)
+tcGRHS :: TcMatchCtxt -> TcRhoType -> GRHS Name -> TcM (GRHS TcId)
tcGRHS ctxt res_ty (GRHS guards rhs)
- = do { (guards', rhs') <- tcStmts stmt_ctxt tcGuardStmt guards res_ty $
+ = do { (guards', rhs') <- tcStmtsAndThen stmt_ctxt tcGuardStmt guards res_ty $
mc_body ctxt rhs
; return (GRHS guards' rhs') }
where
\begin{code}
tcDoStmts :: HsStmtContext Name
-> [LStmt Name]
- -> LHsExpr Name
- -> BoxyRhoType
+ -> TcRhoType
-> TcM (HsExpr TcId) -- Returns a HsDo
-tcDoStmts ListComp stmts body res_ty
- = do { elt_ty <- boxySplitListTy res_ty
- ; (stmts', body') <- tcStmts ListComp (tcLcStmt listTyCon) stmts
- (emptyRefinement,elt_ty) $
- tcBody body
- ; return (HsDo ListComp stmts' body' (mkListTy elt_ty)) }
-
-tcDoStmts PArrComp stmts body res_ty
- = do { [elt_ty] <- boxySplitTyConApp parrTyCon res_ty
- ; (stmts', body') <- tcStmts PArrComp (tcLcStmt parrTyCon) stmts
- (emptyRefinement, elt_ty) $
- tcBody body
- ; return (HsDo PArrComp stmts' body' (mkPArrTy elt_ty)) }
-
-tcDoStmts DoExpr stmts body res_ty
- = do { (m_ty, elt_ty) <- boxySplitAppTy res_ty
- ; let res_ty' = mkAppTy m_ty elt_ty -- The boxySplit consumes res_ty
- ; (stmts', body') <- tcStmts DoExpr (tcDoStmt m_ty) stmts
- (emptyRefinement, res_ty') $
- tcBody body
- ; return (HsDo DoExpr stmts' body' res_ty') }
-
-tcDoStmts ctxt@(MDoExpr _) stmts body res_ty
- = do { (m_ty, elt_ty) <- boxySplitAppTy res_ty
- ; let res_ty' = mkAppTy m_ty elt_ty -- The boxySplit consumes res_ty
- tc_rhs rhs = withBox liftedTypeKind $ \ pat_ty ->
- tcMonoExpr rhs (mkAppTy m_ty pat_ty)
-
- ; (stmts', body') <- tcStmts ctxt (tcMDoStmt tc_rhs) stmts
- (emptyRefinement, res_ty') $
- tcBody body
-
- ; let names = [mfixName, bindMName, thenMName, returnMName, failMName]
- ; insts <- mapM (newMethodFromName DoOrigin m_ty) names
- ; return (HsDo (MDoExpr (names `zip` insts)) stmts' body' res_ty') }
-
-tcDoStmts ctxt stmts body res_ty = pprPanic "tcDoStmts" (pprStmtContext ctxt)
-
-tcBody :: LHsExpr Name -> (Refinement, BoxyRhoType) -> TcM (LHsExpr TcId)
-tcBody body (reft, res_ty)
- = do { traceTc (text "tcBody" <+> ppr res_ty <+> ppr reft)
- ; let (co, res_ty') = refineResType reft res_ty
- ; body' <- tcPolyExpr body res_ty'
- ; return (mkLHsWrap co body') }
+tcDoStmts ListComp stmts res_ty
+ = do { (coi, elt_ty) <- matchExpectedListTy res_ty
+ ; stmts' <- tcStmts ListComp (tcLcStmt listTyCon) stmts elt_ty
+ ; return $ mkHsWrapCoI coi
+ (HsDo ListComp stmts' (mkListTy elt_ty)) }
+
+tcDoStmts PArrComp stmts res_ty
+ = do { (coi, elt_ty) <- matchExpectedPArrTy res_ty
+ ; stmts' <- tcStmts PArrComp (tcLcStmt parrTyCon) stmts elt_ty
+ ; return $ mkHsWrapCoI coi
+ (HsDo PArrComp stmts' (mkPArrTy elt_ty)) }
+
+tcDoStmts DoExpr stmts res_ty
+ = do { stmts' <- tcStmts DoExpr tcDoStmt stmts res_ty
+ ; return (HsDo DoExpr stmts' res_ty) }
+
+tcDoStmts MDoExpr stmts res_ty
+ = do { stmts' <- tcStmts MDoExpr tcDoStmt stmts res_ty
+ ; return (HsDo MDoExpr stmts' res_ty) }
+
+tcDoStmts MonadComp stmts res_ty
+ = do { stmts' <- tcStmts MonadComp tcMcStmt stmts res_ty
+ ; return (HsDo MonadComp stmts' res_ty) }
+
+tcDoStmts ctxt _ _ = pprPanic "tcDoStmts" (pprStmtContext ctxt)
+
+tcBody :: LHsExpr Name -> TcRhoType -> TcM (LHsExpr TcId)
+tcBody body res_ty
+ = do { traceTc "tcBody" (ppr res_ty)
+ ; body' <- tcMonoExpr body res_ty
+ ; return body'
+ }
\end{code}
type TcStmtChecker
= forall thing. HsStmtContext Name
-> Stmt Name
- -> (Refinement, BoxyRhoType) -- Result type for comprehension
- -> ((Refinement,BoxyRhoType) -> TcM thing) -- Checker for what follows the stmt
+ -> TcRhoType -- Result type for comprehension
+ -> (TcRhoType -> TcM thing) -- Checker for what follows the stmt
-> TcM (Stmt TcId, thing)
- -- The incoming BoxyRhoType may be refined by type refinements
- -- before being passed to the thing_inside
-
tcStmts :: HsStmtContext Name
-> TcStmtChecker -- NB: higher-rank type
-> [LStmt Name]
- -> (Refinement, BoxyRhoType)
- -> ((Refinement, BoxyRhoType) -> TcM thing)
- -> TcM ([LStmt TcId], thing)
+ -> TcRhoType
+ -> TcM [LStmt TcId]
+tcStmts ctxt stmt_chk stmts res_ty
+ = do { (stmts', _) <- tcStmtsAndThen ctxt stmt_chk stmts res_ty $
+ const (return ())
+ ; return stmts' }
+
+tcStmtsAndThen :: HsStmtContext Name
+ -> TcStmtChecker -- NB: higher-rank type
+ -> [LStmt Name]
+ -> TcRhoType
+ -> (TcRhoType -> TcM thing)
+ -> TcM ([LStmt TcId], thing)
-- Note the higher-rank type. stmt_chk is applied at different
-- types in the equations for tcStmts
-tcStmts ctxt stmt_chk [] res_ty thing_inside
+tcStmtsAndThen _ _ [] res_ty thing_inside
= do { thing <- thing_inside res_ty
; return ([], thing) }
-- LetStmts are handled uniformly, regardless of context
-tcStmts ctxt stmt_chk (L loc (LetStmt binds) : stmts) res_ty thing_inside
+tcStmtsAndThen ctxt stmt_chk (L loc (LetStmt binds) : stmts) res_ty thing_inside
= do { (binds', (stmts',thing)) <- tcLocalBinds binds $
- tcStmts ctxt stmt_chk stmts res_ty thing_inside
+ tcStmtsAndThen ctxt stmt_chk stmts res_ty thing_inside
; return (L loc (LetStmt binds') : stmts', thing) }
-- For the vanilla case, handle the location-setting part
-tcStmts ctxt stmt_chk (L loc stmt : stmts) res_ty thing_inside
+tcStmtsAndThen ctxt stmt_chk (L loc stmt : stmts) res_ty thing_inside
= do { (stmt', (stmts', thing)) <-
- setSrcSpan loc $
- addErrCtxt (stmtCtxt ctxt stmt) $
- stmt_chk ctxt stmt res_ty $ \ res_ty' ->
- popErrCtxt $
- tcStmts ctxt stmt_chk stmts res_ty' $
+ setSrcSpan loc $
+ addErrCtxt (pprStmtInCtxt ctxt stmt) $
+ stmt_chk ctxt stmt res_ty $ \ res_ty' ->
+ popErrCtxt $
+ tcStmtsAndThen ctxt stmt_chk stmts res_ty' $
thing_inside
; return (L loc stmt' : stmts', thing) }
--------------------------------
-- Pattern guards
tcGuardStmt :: TcStmtChecker
-tcGuardStmt ctxt (ExprStmt guard _ _) res_ty thing_inside
+tcGuardStmt _ (ExprStmt guard _ _ _) res_ty thing_inside
= do { guard' <- tcMonoExpr guard boolTy
; thing <- thing_inside res_ty
- ; return (ExprStmt guard' noSyntaxExpr boolTy, thing) }
+ ; return (ExprStmt guard' noSyntaxExpr noSyntaxExpr boolTy, thing) }
tcGuardStmt ctxt (BindStmt pat rhs _ _) res_ty thing_inside
- = do { (rhs', rhs_ty) <- tcInferRho rhs
- ; (pat', thing) <- tcLamPat pat rhs_ty res_ty thing_inside
+ = do { (rhs', rhs_ty) <- tcInferRhoNC rhs -- Stmt has a context already
+ ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat rhs_ty $
+ thing_inside res_ty
; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
-tcGuardStmt ctxt stmt res_ty thing_inside
+tcGuardStmt _ stmt _ _
= pprPanic "tcGuardStmt: unexpected Stmt" (ppr stmt)
tcLcStmt :: TyCon -- The list/Parray type constructor ([] or PArray)
-> TcStmtChecker
+tcLcStmt _ _ (LastStmt body _) elt_ty thing_inside
+ = do { body' <- tcMonoExpr body elt_ty
+ ; thing <- thing_inside (panic "tcLcStmt: thing_inside")
+ ; return (LastStmt body' noSyntaxExpr, thing) }
+
-- A generator, pat <- rhs
-tcLcStmt m_tc ctxt (BindStmt pat rhs _ _) res_ty thing_inside
- = do { (rhs', pat_ty) <- withBox liftedTypeKind $ \ ty ->
- tcMonoExpr rhs (mkTyConApp m_tc [ty])
- ; (pat', thing) <- tcLamPat pat pat_ty res_ty thing_inside
+tcLcStmt m_tc ctxt (BindStmt pat rhs _ _) elt_ty thing_inside
+ = do { pat_ty <- newFlexiTyVarTy liftedTypeKind
+ ; rhs' <- tcMonoExpr rhs (mkTyConApp m_tc [pat_ty])
+ ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat pat_ty $
+ thing_inside elt_ty
; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
-- A boolean guard
-tcLcStmt m_tc ctxt (ExprStmt rhs _ _) res_ty thing_inside
+tcLcStmt _ _ (ExprStmt rhs _ _ _) elt_ty thing_inside
= do { rhs' <- tcMonoExpr rhs boolTy
- ; thing <- thing_inside res_ty
- ; return (ExprStmt rhs' noSyntaxExpr boolTy, thing) }
+ ; thing <- thing_inside elt_ty
+ ; return (ExprStmt rhs' noSyntaxExpr noSyntaxExpr boolTy, thing) }
-- A parallel set of comprehensions
-- [ (g x, h x) | ... ; let g v = ...
-- | ... ; let h v = ... ]
--
-- It's possible that g,h are overloaded, so we need to feed the LIE from the
--- (g x, h x) up through both lots of bindings (so we get the bindInstsOfLocalFuns).
+-- (g x, h x) up through both lots of bindings (so we get the bindLocalMethods).
-- Similarly if we had an existential pattern match:
--
-- data T = forall a. Show a => C a
-- So the binders of the first parallel group will be in scope in the second
-- group. But that's fine; there's no shadowing to worry about.
-tcLcStmt m_tc ctxt (ParStmt bndr_stmts_s) elt_ty thing_inside
+tcLcStmt m_tc ctxt (ParStmt bndr_stmts_s _ _ _) elt_ty thing_inside
= do { (pairs', thing) <- loop bndr_stmts_s
- ; return (ParStmt pairs', thing) }
+ ; return (ParStmt pairs' noSyntaxExpr noSyntaxExpr noSyntaxExpr, thing) }
where
-- loop :: [([LStmt Name], [Name])] -> TcM ([([LStmt TcId], [TcId])], thing)
- loop [] = do { thing <- thing_inside elt_ty -- No refinement from pattern
+ loop [] = do { thing <- thing_inside elt_ty
; return ([], thing) } -- matching in the branches
loop ((stmts, names) : pairs)
= do { (stmts', (ids, pairs', thing))
- <- tcStmts ctxt (tcLcStmt m_tc) stmts elt_ty $ \ elt_ty' ->
+ <- tcStmtsAndThen ctxt (tcLcStmt m_tc) stmts elt_ty $ \ _elt_ty' ->
do { ids <- tcLookupLocalIds names
; (pairs', thing) <- loop pairs
; return (ids, pairs', thing) }
; return ( (stmts', ids) : pairs', thing ) }
-tcLcStmt m_tc ctxt stmt elt_ty thing_inside
+tcLcStmt m_tc ctxt (TransformStmt stmts binders usingExpr maybeByExpr _ _) elt_ty thing_inside = do
+ (stmts', (binders', usingExpr', maybeByExpr', thing)) <-
+ tcStmtsAndThen (TransformStmtCtxt ctxt) (tcLcStmt m_tc) stmts elt_ty $ \elt_ty' -> do
+ let alphaListTy = mkTyConApp m_tc [alphaTy]
+
+ (usingExpr', maybeByExpr') <-
+ case maybeByExpr of
+ Nothing -> do
+ -- We must validate that usingExpr :: forall a. [a] -> [a]
+ let using_ty = mkForAllTy alphaTyVar (alphaListTy `mkFunTy` alphaListTy)
+ usingExpr' <- tcPolyExpr usingExpr using_ty
+ return (usingExpr', Nothing)
+ Just byExpr -> do
+ -- We must infer a type such that e :: t and then check that
+ -- usingExpr :: forall a. (a -> t) -> [a] -> [a]
+ (byExpr', tTy) <- tcInferRhoNC byExpr
+ let using_ty = mkForAllTy alphaTyVar $
+ (alphaTy `mkFunTy` tTy)
+ `mkFunTy` alphaListTy `mkFunTy` alphaListTy
+ usingExpr' <- tcPolyExpr usingExpr using_ty
+ return (usingExpr', Just byExpr')
+
+ binders' <- tcLookupLocalIds binders
+ thing <- thing_inside elt_ty'
+
+ return (binders', usingExpr', maybeByExpr', thing)
+
+ return (TransformStmt stmts' binders' usingExpr' maybeByExpr' noSyntaxExpr noSyntaxExpr, thing)
+
+tcLcStmt m_tc ctxt (GroupStmt { grpS_stmts = stmts, grpS_bndrs = bindersMap
+ , grpS_by = by, grpS_using = using
+ , grpS_explicit = explicit }) elt_ty thing_inside
+ = do { let (bndr_names, list_bndr_names) = unzip bindersMap
+
+ ; (stmts', (bndr_ids, by', using_ty, elt_ty')) <-
+ tcStmtsAndThen (TransformStmtCtxt ctxt) (tcLcStmt m_tc) stmts elt_ty $ \elt_ty' -> do
+ (by', using_ty) <-
+ case by of
+ Nothing -> -- check that using :: forall a. [a] -> [[a]]
+ return (Nothing, mkForAllTy alphaTyVar $
+ alphaListTy `mkFunTy` alphaListListTy)
+
+ Just by_e -> -- check that using :: forall a. (a -> t) -> [a] -> [[a]]
+ -- where by :: t
+ do { (by_e', t_ty) <- tcInferRhoNC by_e
+ ; return (Just by_e', mkForAllTy alphaTyVar $
+ (alphaTy `mkFunTy` t_ty)
+ `mkFunTy` alphaListTy
+ `mkFunTy` alphaListListTy) }
+ -- Find the Ids (and hence types) of all old binders
+ bndr_ids <- tcLookupLocalIds bndr_names
+
+ return (bndr_ids, by', using_ty, elt_ty')
+
+ -- Ensure that every old binder of type b is linked up with
+ -- its new binder which should have type [b]
+ ; let list_bndr_ids = zipWith mk_list_bndr list_bndr_names bndr_ids
+ bindersMap' = bndr_ids `zip` list_bndr_ids
+ -- See Note [GroupStmt binder map] in HsExpr
+
+ ; using' <- tcPolyExpr using using_ty
+
+ -- Type check the thing in the environment with
+ -- these new binders and return the result
+ ; thing <- tcExtendIdEnv list_bndr_ids (thing_inside elt_ty')
+ ; return (emptyGroupStmt { grpS_stmts = stmts', grpS_bndrs = bindersMap'
+ , grpS_by = by', grpS_using = using'
+ , grpS_explicit = explicit }, thing) }
+ where
+ alphaListTy = mkTyConApp m_tc [alphaTy]
+ alphaListListTy = mkTyConApp m_tc [alphaListTy]
+
+ mk_list_bndr :: Name -> TcId -> TcId
+ mk_list_bndr list_bndr_name bndr_id
+ = mkLocalId list_bndr_name (mkTyConApp m_tc [idType bndr_id])
+
+tcLcStmt _ _ stmt _ _
= pprPanic "tcLcStmt: unexpected Stmt" (ppr stmt)
+
+
+--------------------------------
+-- Monad comprehensions
+
+tcMcStmt :: TcStmtChecker
+
+tcMcStmt _ (LastStmt body return_op) res_ty thing_inside
+ = do { a_ty <- newFlexiTyVarTy liftedTypeKind
+ ; return_op' <- tcSyntaxOp MCompOrigin return_op
+ (a_ty `mkFunTy` res_ty)
+ ; body' <- tcMonoExpr body a_ty
+ ; thing <- thing_inside (panic "tcMcStmt: thing_inside")
+ ; return (LastStmt body' return_op', thing) }
+
+-- Generators for monad comprehensions ( pat <- rhs )
+--
+-- [ body | q <- gen ] -> gen :: m a
+-- q :: a
+--
+
+tcMcStmt ctxt (BindStmt pat rhs bind_op fail_op) res_ty thing_inside
+ = do { rhs_ty <- newFlexiTyVarTy liftedTypeKind
+ ; pat_ty <- newFlexiTyVarTy liftedTypeKind
+ ; new_res_ty <- newFlexiTyVarTy liftedTypeKind
+
+ -- (>>=) :: rhs_ty -> (pat_ty -> new_res_ty) -> res_ty
+ ; bind_op' <- tcSyntaxOp MCompOrigin bind_op
+ (mkFunTys [rhs_ty, mkFunTy pat_ty new_res_ty] res_ty)
+
+ -- If (but only if) the pattern can fail, typecheck the 'fail' operator
+ ; fail_op' <- if isIrrefutableHsPat pat
+ then return noSyntaxExpr
+ else tcSyntaxOp MCompOrigin fail_op (mkFunTy stringTy new_res_ty)
+
+ ; rhs' <- tcMonoExprNC rhs rhs_ty
+ ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat pat_ty $
+ thing_inside new_res_ty
+
+ ; return (BindStmt pat' rhs' bind_op' fail_op', thing) }
+
+-- Boolean expressions.
+--
+-- [ body | stmts, expr ] -> expr :: m Bool
+--
+tcMcStmt _ (ExprStmt rhs then_op guard_op _) res_ty thing_inside
+ = do { -- Deal with rebindable syntax:
+ -- guard_op :: test_ty -> rhs_ty
+ -- then_op :: rhs_ty -> new_res_ty -> res_ty
+ -- Where test_ty is, for example, Bool
+ test_ty <- newFlexiTyVarTy liftedTypeKind
+ ; rhs_ty <- newFlexiTyVarTy liftedTypeKind
+ ; new_res_ty <- newFlexiTyVarTy liftedTypeKind
+ ; rhs' <- tcMonoExpr rhs test_ty
+ ; guard_op' <- tcSyntaxOp MCompOrigin guard_op
+ (mkFunTy test_ty rhs_ty)
+ ; then_op' <- tcSyntaxOp MCompOrigin then_op
+ (mkFunTys [rhs_ty, new_res_ty] res_ty)
+ ; thing <- thing_inside new_res_ty
+ ; return (ExprStmt rhs' then_op' guard_op' rhs_ty, thing) }
+
+-- Transform statements.
+--
+-- [ body | stmts, then f ] -> f :: forall a. m a -> m a
+-- [ body | stmts, then f by e ] -> f :: forall a. (a -> t) -> m a -> m a
+--
+tcMcStmt ctxt (TransformStmt stmts binders usingExpr maybeByExpr return_op bind_op) res_ty thing_inside
+ = do {
+ -- We don't know the types of binders yet, so we use this dummy and
+ -- later unify this type with the `m_bndr_ty`
+ ty_dummy <- newFlexiTyVarTy liftedTypeKind
+
+ ; (stmts', (binders', usingExpr', maybeByExpr', return_op', bind_op', thing)) <-
+ tcStmtsAndThen (TransformStmtCtxt ctxt) tcMcStmt stmts ty_dummy $ \res_ty' -> do
+ { (_, (m_ty, _)) <- matchExpectedAppTy res_ty'
+ ; (usingExpr', maybeByExpr') <-
+ case maybeByExpr of
+ Nothing -> do
+ -- We must validate that usingExpr :: forall a. m a -> m a
+ let using_ty = mkForAllTy alphaTyVar $
+ (m_ty `mkAppTy` alphaTy)
+ `mkFunTy`
+ (m_ty `mkAppTy` alphaTy)
+ usingExpr' <- tcPolyExpr usingExpr using_ty
+ return (usingExpr', Nothing)
+ Just byExpr -> do
+ -- We must infer a type such that e :: t and then check that
+ -- usingExpr :: forall a. (a -> t) -> m a -> m a
+ (byExpr', tTy) <- tcInferRhoNC byExpr
+ let using_ty = mkForAllTy alphaTyVar $
+ (alphaTy `mkFunTy` tTy)
+ `mkFunTy`
+ (m_ty `mkAppTy` alphaTy)
+ `mkFunTy`
+ (m_ty `mkAppTy` alphaTy)
+ usingExpr' <- tcPolyExpr usingExpr using_ty
+ return (usingExpr', Just byExpr')
+
+ ; bndr_ids <- tcLookupLocalIds binders
+
+ -- `return` and `>>=` are used to pass around/modify our
+ -- binders, so we know their types:
+ --
+ -- return :: (a,b,c,..) -> m (a,b,c,..)
+ -- (>>=) :: m (a,b,c,..)
+ -- -> ( (a,b,c,..) -> m (a,b,c,..) )
+ -- -> m (a,b,c,..)
+ --
+ ; let bndr_ty = mkBigCoreVarTupTy bndr_ids
+ m_bndr_ty = m_ty `mkAppTy` bndr_ty
+
+ ; return_op' <- tcSyntaxOp MCompOrigin return_op
+ (bndr_ty `mkFunTy` m_bndr_ty)
+
+ ; bind_op' <- tcSyntaxOp MCompOrigin bind_op $
+ m_bndr_ty `mkFunTy` (bndr_ty `mkFunTy` res_ty)
+ `mkFunTy` res_ty
+
+ -- Unify types of the inner comprehension and the binders type
+ ; _ <- unifyType res_ty' m_bndr_ty
+
+ -- Typecheck the `thing` with out old type (which is the type
+ -- of the final result of our comprehension)
+ ; thing <- thing_inside res_ty
+
+ ; return (bndr_ids, usingExpr', maybeByExpr', return_op', bind_op', thing) }
+
+ ; return (TransformStmt stmts' binders' usingExpr' maybeByExpr' return_op' bind_op', thing) }
+
+-- Grouping statements
+--
+-- [ body | stmts, then group by e ]
+-- -> e :: t
+-- [ body | stmts, then group by e using f ]
+-- -> e :: t
+-- f :: forall a. (a -> t) -> m a -> m (m a)
+-- [ body | stmts, then group using f ]
+-- -> f :: forall a. m a -> m (m a)
+--
+tcMcStmt ctxt (GroupStmt { grpS_stmts = stmts, grpS_bndrs = bindersMap
+ , grpS_by = by, grpS_using = using, grpS_explicit = explicit
+ , grpS_ret = return_op, grpS_bind = bind_op
+ , grpS_fmap = fmap_op }) res_ty thing_inside
+ = do { let star_star_kind = liftedTypeKind `mkArrowKind` liftedTypeKind
+ ; m1_ty <- newFlexiTyVarTy star_star_kind
+ ; m2_ty <- newFlexiTyVarTy star_star_kind
+ ; n_ty <- newFlexiTyVarTy star_star_kind
+ ; tup_ty_var <- newFlexiTyVarTy liftedTypeKind
+ ; new_res_ty <- newFlexiTyVarTy liftedTypeKind
+ ; let (bndr_names, n_bndr_names) = unzip bindersMap
+ m1_tup_ty = m1_ty `mkAppTy` tup_ty_var
+
+ -- 'stmts' returns a result of type (m1_ty tuple_ty),
+ -- typically something like [(Int,Bool,Int)]
+ -- We don't know what tuple_ty is yet, so we use a variable
+ ; (stmts', (bndr_ids, by_e_ty, return_op')) <-
+ tcStmtsAndThen (TransformStmtCtxt ctxt) tcMcStmt stmts m1_tup_ty $ \res_ty' -> do
+ { by_e_ty <- case by of
+ Nothing -> return Nothing
+ Just e -> do { e_ty <- tcInferRhoNC e; return (Just e_ty) }
+
+ -- Find the Ids (and hence types) of all old binders
+ ; bndr_ids <- tcLookupLocalIds bndr_names
+
+ -- 'return' is only used for the binders, so we know its type.
+ --
+ -- return :: (a,b,c,..) -> m (a,b,c,..)
+ ; return_op' <- tcSyntaxOp MCompOrigin return_op $
+ (mkBigCoreVarTupTy bndr_ids) `mkFunTy` res_ty'
+
+ ; return (bndr_ids, by_e_ty, return_op') }
+
+
+
+ ; let tup_ty = mkBigCoreVarTupTy bndr_ids -- (a,b,c)
+ using_arg_ty = m1_ty `mkAppTy` tup_ty -- m1 (a,b,c)
+ n_tup_ty = n_ty `mkAppTy` tup_ty -- n (a,b,c)
+ using_res_ty = m2_ty `mkAppTy` n_tup_ty -- m2 (n (a,b,c))
+ using_fun_ty = using_arg_ty `mkFunTy` using_arg_ty
+
+ -- (>>=) :: m2 (n (a,b,c)) -> ( n (a,b,c) -> new_res_ty ) -> res_ty
+ -- using :: ((a,b,c)->t) -> m1 (a,b,c) -> m2 (n (a,b,c))
+
+ --------------- Typecheck the 'bind' function -------------
+ ; bind_op' <- tcSyntaxOp MCompOrigin bind_op $
+ using_res_ty `mkFunTy` (n_tup_ty `mkFunTy` new_res_ty)
+ `mkFunTy` res_ty
+
+ --------------- Typecheck the 'using' function -------------
+ ; let poly_fun_ty = (m1_ty `mkAppTy` alphaTy) `mkFunTy`
+ (m2_ty `mkAppTy` (n_ty `mkAppTy` alphaTy))
+ using_poly_ty = case by_e_ty of
+ Nothing -> mkForAllTy alphaTyVar poly_fun_ty
+ -- using :: forall a. m1 a -> m2 (n a)
+
+ Just (_,t_ty) -> mkForAllTy alphaTyVar $
+ (alphaTy `mkFunTy` t_ty) `mkFunTy` poly_fun_ty
+ -- using :: forall a. (a->t) -> m1 a -> m2 (n a)
+ -- where by :: t
+
+ ; using' <- tcPolyExpr using using_poly_ty
+ ; coi <- unifyType (applyTy using_poly_ty tup_ty)
+ (case by_e_ty of
+ Nothing -> using_fun_ty
+ Just (_,t_ty) -> (tup_ty `mkFunTy` t_ty) `mkFunTy` using_fun_ty)
+ ; let final_using = fmap (mkHsWrapCoI coi . HsWrap (WpTyApp tup_ty)) using'
+
+ --------------- Typecheck the 'fmap' function -------------
+ ; fmap_op' <- fmap unLoc . tcPolyExpr (noLoc fmap_op) $
+ mkForAllTy alphaTyVar $ mkForAllTy betaTyVar $
+ (alphaTy `mkFunTy` betaTy)
+ `mkFunTy` (n_ty `mkAppTy` alphaTy)
+ `mkFunTy` (n_ty `mkAppTy` betaTy)
+
+ ; let mk_n_bndr :: Name -> TcId -> TcId
+ mk_n_bndr n_bndr_name bndr_id
+ = mkLocalId n_bndr_name (n_ty `mkAppTy` idType bndr_id)
+
+ -- Ensure that every old binder of type `b` is linked up with its
+ -- new binder which should have type `n b`
+ -- See Note [GroupStmt binder map] in HsExpr
+ n_bndr_ids = zipWith mk_n_bndr n_bndr_names bndr_ids
+ bindersMap' = bndr_ids `zip` n_bndr_ids
+
+ -- Type check the thing in the environment with these new binders and
+ -- return the result
+ ; thing <- tcExtendIdEnv n_bndr_ids (thing_inside res_ty)
+
+ ; return (GroupStmt { grpS_stmts = stmts', grpS_bndrs = bindersMap'
+ , grpS_by = fmap fst by_e_ty, grpS_using = final_using
+ , grpS_ret = return_op', grpS_bind = bind_op'
+ , grpS_fmap = fmap_op', grpS_explicit = explicit }, thing) }
+
+-- Typecheck `ParStmt`. See `tcLcStmt` for more informations about typechecking
+-- of `ParStmt`s.
+--
+-- Note: The `mzip` function will get typechecked via:
+--
+-- ParStmt [st1::t1, st2::t2, st3::t3]
+--
+-- mzip :: m st1
+-- -> (m st2 -> m st3 -> m (st2, st3)) -- recursive call
+-- -> m (st1, (st2, st3))
+--
+tcMcStmt ctxt (ParStmt bndr_stmts_s mzip_op bind_op return_op) res_ty thing_inside
+ = do { (_,(m_ty,_)) <- matchExpectedAppTy res_ty
+ -- ToDo: what if the coercion isn't the identity?
+
+ ; (pairs', thing) <- loop m_ty bndr_stmts_s
+
+ ; let mzip_ty = mkForAllTys [alphaTyVar, betaTyVar] $
+ (m_ty `mkAppTy` alphaTy)
+ `mkFunTy`
+ (m_ty `mkAppTy` betaTy)
+ `mkFunTy`
+ (m_ty `mkAppTy` mkBoxedTupleTy [alphaTy, betaTy])
+ ; mzip_op' <- unLoc `fmap` tcPolyExpr (noLoc mzip_op) mzip_ty
+
+ -- Typecheck bind:
+ ; let tys = map (mkBigCoreVarTupTy . snd) pairs'
+ tuple_ty = mk_tuple_ty tys
+
+ ; bind_op' <- tcSyntaxOp MCompOrigin bind_op $
+ (m_ty `mkAppTy` tuple_ty)
+ `mkFunTy`
+ (tuple_ty `mkFunTy` res_ty)
+ `mkFunTy`
+ res_ty
+
+ ; return_op' <- fmap unLoc . tcPolyExpr (noLoc return_op) $
+ mkForAllTy alphaTyVar $
+ alphaTy `mkFunTy` (m_ty `mkAppTy` alphaTy)
+
+ ; return (ParStmt pairs' mzip_op' bind_op' return_op', thing) }
+
+ where mk_tuple_ty tys = foldr1 (\tn tm -> mkBoxedTupleTy [tn, tm]) tys
+
+ -- loop :: Type -- m_ty
+ -- -> [([LStmt Name], [Name])]
+ -- -> TcM ([([LStmt TcId], [TcId])], thing)
+ loop _ [] = do { thing <- thing_inside res_ty
+ ; return ([], thing) } -- matching in the branches
+
+ loop m_ty ((stmts, names) : pairs)
+ = do { -- type dummy since we don't know all binder types yet
+ ty_dummy <- newFlexiTyVarTy liftedTypeKind
+ ; (stmts', (ids, pairs', thing))
+ <- tcStmtsAndThen ctxt tcMcStmt stmts ty_dummy $ \res_ty' ->
+ do { ids <- tcLookupLocalIds names
+ ; _ <- unifyType res_ty' (m_ty `mkAppTy` mkBigCoreVarTupTy ids)
+ ; (pairs', thing) <- loop m_ty pairs
+ ; return (ids, pairs', thing) }
+ ; return ( (stmts', ids) : pairs', thing ) }
+
+tcMcStmt _ stmt _ _
+ = pprPanic "tcMcStmt: unexpected Stmt" (ppr stmt)
--------------------------------
-- Do-notation
-- The main excitement here is dealing with rebindable syntax
-tcDoStmt :: TcType -- Monad type, m
- -> TcStmtChecker
+tcDoStmt :: TcStmtChecker
+
+tcDoStmt _ (LastStmt body _) res_ty thing_inside
+ = do { body' <- tcMonoExprNC body res_ty
+ ; thing <- thing_inside (panic "tcDoStmt: thing_inside")
+ ; return (LastStmt body' noSyntaxExpr, thing) }
+
+tcDoStmt ctxt (BindStmt pat rhs bind_op fail_op) res_ty thing_inside
+ = do { -- Deal with rebindable syntax:
+ -- (>>=) :: rhs_ty -> (pat_ty -> new_res_ty) -> res_ty
+ -- This level of generality is needed for using do-notation
+ -- in full generality; see Trac #1537
+
+ -- I'd like to put this *after* the tcSyntaxOp
+ -- (see Note [Treat rebindable syntax first], but that breaks
+ -- the rigidity info for GADTs. When we move to the new story
+ -- for GADTs, we can move this after tcSyntaxOp
+ rhs_ty <- newFlexiTyVarTy liftedTypeKind
+ ; pat_ty <- newFlexiTyVarTy liftedTypeKind
+ ; new_res_ty <- newFlexiTyVarTy liftedTypeKind
+ ; bind_op' <- tcSyntaxOp DoOrigin bind_op
+ (mkFunTys [rhs_ty, mkFunTy pat_ty new_res_ty] res_ty)
-tcDoStmt m_ty ctxt (BindStmt pat rhs bind_op fail_op) reft_res_ty@(_,res_ty) thing_inside
- = do { (rhs', pat_ty) <- withBox liftedTypeKind $ \ pat_ty ->
- tcMonoExpr rhs (mkAppTy m_ty pat_ty)
- -- We should use type *inference* for the RHS computations, becuase of GADTs.
- -- do { pat <- rhs; <rest> }
- -- is rather like
- -- case rhs of { pat -> <rest> }
- -- We do inference on rhs, so that information about its type can be refined
- -- when type-checking the pattern.
-
- ; (pat', thing) <- tcLamPat pat pat_ty reft_res_ty thing_inside
-
- -- Deal with rebindable syntax; (>>=) :: m a -> (a -> m b) -> m b
- ; let bind_ty = mkFunTys [mkAppTy m_ty pat_ty,
- mkFunTy pat_ty res_ty] res_ty
- ; bind_op' <- tcSyntaxOp DoOrigin bind_op bind_ty
-- If (but only if) the pattern can fail,
-- typecheck the 'fail' operator
- ; fail_op' <- if isIrrefutableHsPat pat'
+ ; fail_op' <- if isIrrefutableHsPat pat
then return noSyntaxExpr
- else tcSyntaxOp DoOrigin fail_op (mkFunTy stringTy res_ty)
- ; return (BindStmt pat' rhs' bind_op' fail_op', thing) }
+ else tcSyntaxOp DoOrigin fail_op (mkFunTy stringTy new_res_ty)
+ ; rhs' <- tcMonoExprNC rhs rhs_ty
+ ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat pat_ty $
+ thing_inside new_res_ty
+
+ ; return (BindStmt pat' rhs' bind_op' fail_op', thing) }
-tcDoStmt m_ty ctxt (ExprStmt rhs then_op _) reft_res_ty@(_,res_ty) thing_inside
- = do { -- Deal with rebindable syntax; (>>) :: m a -> m b -> m b
- a_ty <- newFlexiTyVarTy liftedTypeKind
- ; let rhs_ty = mkAppTy m_ty a_ty
- then_ty = mkFunTys [rhs_ty, res_ty] res_ty
- ; then_op' <- tcSyntaxOp DoOrigin then_op then_ty
- ; rhs' <- tcPolyExpr rhs rhs_ty
- ; thing <- thing_inside reft_res_ty
- ; return (ExprStmt rhs' then_op' rhs_ty, thing) }
-tcDoStmt m_ty ctxt stmt res_ty thing_inside
+tcDoStmt _ (ExprStmt rhs then_op _ _) res_ty thing_inside
+ = do { -- Deal with rebindable syntax;
+ -- (>>) :: rhs_ty -> new_res_ty -> res_ty
+ -- See also Note [Treat rebindable syntax first]
+ rhs_ty <- newFlexiTyVarTy liftedTypeKind
+ ; new_res_ty <- newFlexiTyVarTy liftedTypeKind
+ ; then_op' <- tcSyntaxOp DoOrigin then_op
+ (mkFunTys [rhs_ty, new_res_ty] res_ty)
+
+ ; rhs' <- tcMonoExprNC rhs rhs_ty
+ ; thing <- thing_inside new_res_ty
+ ; return (ExprStmt rhs' then_op' noSyntaxExpr rhs_ty, thing) }
+
+tcDoStmt ctxt (RecStmt { recS_stmts = stmts, recS_later_ids = later_names
+ , recS_rec_ids = rec_names, recS_ret_fn = ret_op
+ , recS_mfix_fn = mfix_op, recS_bind_fn = bind_op })
+ res_ty thing_inside
+ = do { let tup_names = rec_names ++ filterOut (`elem` rec_names) later_names
+ ; tup_elt_tys <- newFlexiTyVarTys (length tup_names) liftedTypeKind
+ ; let tup_ids = zipWith mkLocalId tup_names tup_elt_tys
+ tup_ty = mkBoxedTupleTy tup_elt_tys
+
+ ; tcExtendIdEnv tup_ids $ do
+ { stmts_ty <- newFlexiTyVarTy liftedTypeKind
+ ; (stmts', (ret_op', tup_rets))
+ <- tcStmtsAndThen ctxt tcDoStmt stmts stmts_ty $ \ inner_res_ty ->
+ do { tup_rets <- zipWithM tcCheckId tup_names tup_elt_tys
+ -- Unify the types of the "final" Ids (which may
+ -- be polymorphic) with those of "knot-tied" Ids
+ ; ret_op' <- tcSyntaxOp DoOrigin ret_op (mkFunTy tup_ty inner_res_ty)
+ ; return (ret_op', tup_rets) }
+
+ ; mfix_res_ty <- newFlexiTyVarTy liftedTypeKind
+ ; mfix_op' <- tcSyntaxOp DoOrigin mfix_op
+ (mkFunTy (mkFunTy tup_ty stmts_ty) mfix_res_ty)
+
+ ; new_res_ty <- newFlexiTyVarTy liftedTypeKind
+ ; bind_op' <- tcSyntaxOp DoOrigin bind_op
+ (mkFunTys [mfix_res_ty, mkFunTy tup_ty new_res_ty] res_ty)
+
+ ; thing <- thing_inside new_res_ty
+-- ; lie_binds <- bindLocalMethods lie tup_ids
+
+ ; let rec_ids = takeList rec_names tup_ids
+ ; later_ids <- tcLookupLocalIds later_names
+ ; traceTc "tcdo" $ vcat [ppr rec_ids <+> ppr (map idType rec_ids),
+ ppr later_ids <+> ppr (map idType later_ids)]
+ ; return (RecStmt { recS_stmts = stmts', recS_later_ids = later_ids
+ , recS_rec_ids = rec_ids, recS_ret_fn = ret_op'
+ , recS_mfix_fn = mfix_op', recS_bind_fn = bind_op'
+ , recS_rec_rets = tup_rets, recS_ret_ty = stmts_ty }, thing)
+ }}
+
+tcDoStmt _ stmt _ _
= pprPanic "tcDoStmt: unexpected Stmt" (ppr stmt)
+\end{code}
+Note [Treat rebindable syntax first]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+When typechecking
+ do { bar; ... } :: IO ()
+we want to typecheck 'bar' in the knowledge that it should be an IO thing,
+pushing info from the context into the RHS. To do this, we check the
+rebindable syntax first, and push that information into (tcMonoExprNC rhs).
+Otherwise the error shows up when cheking the rebindable syntax, and
+the expected/inferred stuff is back to front (see Trac #3613).
+
+\begin{code}
--------------------------------
-- Mdo-notation
-- The distinctive features here are
tcMDoStmt :: (LHsExpr Name -> TcM (LHsExpr TcId, TcType)) -- RHS inference
-> TcStmtChecker
-tcMDoStmt tc_rhs ctxt (BindStmt pat rhs bind_op fail_op) res_ty thing_inside
+-- Used only by TcArrows... should be gotten rid of
+tcMDoStmt tc_rhs ctxt (BindStmt pat rhs _ _) res_ty thing_inside
= do { (rhs', pat_ty) <- tc_rhs rhs
- ; (pat', thing) <- tcLamPat pat pat_ty res_ty thing_inside
+ ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat pat_ty $
+ thing_inside res_ty
; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
-tcMDoStmt tc_rhs ctxt (ExprStmt rhs then_op _) res_ty thing_inside
+tcMDoStmt tc_rhs _ (ExprStmt rhs _ _ _) res_ty thing_inside
= do { (rhs', elt_ty) <- tc_rhs rhs
; thing <- thing_inside res_ty
- ; return (ExprStmt rhs' noSyntaxExpr elt_ty, thing) }
+ ; return (ExprStmt rhs' noSyntaxExpr noSyntaxExpr elt_ty, thing) }
-tcMDoStmt tc_rhs ctxt (RecStmt stmts laterNames recNames _ _) res_ty thing_inside
+tcMDoStmt tc_rhs ctxt (RecStmt { recS_stmts = stmts, recS_later_ids = laterNames
+ , recS_rec_ids = recNames }) res_ty thing_inside
= do { rec_tys <- newFlexiTyVarTys (length recNames) liftedTypeKind
; let rec_ids = zipWith mkLocalId recNames rec_tys
- ; tcExtendIdEnv rec_ids $ do
+ ; tcExtendIdEnv rec_ids $ do
{ (stmts', (later_ids, rec_rets))
- <- tcStmts ctxt (tcMDoStmt tc_rhs) stmts res_ty $ \ res_ty' ->
+ <- tcStmtsAndThen ctxt (tcMDoStmt tc_rhs) stmts res_ty $ \ _res_ty' ->
-- ToDo: res_ty not really right
- do { rec_rets <- zipWithM tc_ret recNames rec_tys
+ do { rec_rets <- zipWithM tcCheckId recNames rec_tys
; later_ids <- tcLookupLocalIds laterNames
; return (later_ids, rec_rets) }
- ; (thing,lie) <- tcExtendIdEnv later_ids (getLIE (thing_inside res_ty))
+ ; thing <- tcExtendIdEnv later_ids (thing_inside res_ty)
-- NB: The rec_ids for the recursive things
-- already scope over this part. This binding may shadow
-- some of them with polymorphic things with the same Name
-- (see note [RecStmt] in HsExpr)
- ; lie_binds <- bindInstsOfLocalFuns lie later_ids
-
- ; return (RecStmt stmts' later_ids rec_ids rec_rets lie_binds, thing)
+
+ ; return (emptyRecStmt { recS_stmts = stmts', recS_later_ids = later_ids
+ , recS_rec_ids = rec_ids, recS_rec_rets = rec_rets
+ , recS_ret_ty = res_ty }, thing)
}}
- where
- -- Unify the types of the "final" Ids with those of "knot-tied" Ids
- tc_ret rec_name mono_ty
- = do { poly_id <- tcLookupId rec_name
- -- poly_id may have a polymorphic type
- -- but mono_ty is just a monomorphic type variable
- ; co_fn <- tcSubExp (idType poly_id) mono_ty
- ; return (mkHsWrap co_fn (HsVar poly_id)) }
-
-tcMDoStmt tc_rhs ctxt stmt res_ty thing_inside
- = pprPanic "tcMDoStmt: unexpected Stmt" (ppr stmt)
+tcMDoStmt _ _ stmt _ _
+ = pprPanic "tcMDoStmt: unexpected Stmt" (ppr stmt)
\end{code}
checkArgs fun (MatchGroup (match1:matches) _)
| null bad_matches = return ()
| otherwise
- = failWithTc (vcat [ptext SLIT("Equations for") <+> quotes (ppr fun) <+>
- ptext SLIT("have different numbers of arguments"),
+ = failWithTc (vcat [ptext (sLit "Equations for") <+> quotes (ppr fun) <+>
+ ptext (sLit "have different numbers of arguments"),
nest 2 (ppr (getLoc match1)),
nest 2 (ppr (getLoc (head bad_matches)))])
where
args_in_match :: LMatch Name -> Int
args_in_match (L _ (Match pats _ _)) = length pats
-checkArgs fun other = panic "TcPat.checkArgs" -- Matches always non-empty
+checkArgs fun _ = pprPanic "TcPat.checkArgs" (ppr fun) -- Matches always non-empty
\end{code}
-\begin{code}
-matchCtxt ctxt match = hang (ptext SLIT("In") <+> pprMatchContext ctxt <> colon)
- 4 (pprMatch ctxt match)
-
-stmtCtxt ctxt stmt = hang (ptext SLIT("In") <+> pprStmtContext ctxt <> colon)
- 4 (ppr stmt)
-\end{code}
projects / ghc-hetmet.git / blobdiff