\begin{code}
module TcMatches ( tcMatchesFun, tcGRHSsPat, tcMatchesCase, tcMatchLambda,
- tcMatchPats, matchCtxt, TcMatchCtxt(..),
+ matchCtxt, TcMatchCtxt(..),
tcStmts, tcDoStmts,
- tcDoStmt, tcMDoStmt, tcGuardStmt,
- tcThingWithSig
+ tcDoStmt, tcMDoStmt, tcGuardStmt
) where
#include "HsVersions.h"
-import {-# SOURCE #-} TcExpr( tcSyntaxOp, tcCheckRho, tcInferRho, tcMonoExpr, tcCheckSigma )
+import {-# SOURCE #-} TcExpr( tcSyntaxOp, tcInferRho, tcMonoExpr, tcPolyExpr )
import HsSyn ( HsExpr(..), LHsExpr, MatchGroup(..),
Match(..), LMatch, GRHSs(..), GRHS(..),
Stmt(..), LStmt, HsMatchContext(..), HsStmtContext(..),
- LPat, pprMatch, isIrrefutableHsPat,
- pprMatchContext, pprStmtContext, pprMatchRhsContext,
- collectPatsBinders, noSyntaxExpr
- )
-import TcHsSyn ( ExprCoFn, isIdCoercion, (<$>), (<.>) )
+ pprMatch, isIrrefutableHsPat,
+ pprMatchContext, pprStmtContext,
+ noSyntaxExpr, matchGroupArity, pprMatches,
+ ExprCoFn )
import TcRnMonad
-import TcHsType ( tcHsPatSigType, UserTypeCtxt(..) )
-import Inst ( tcInstCall, newMethodFromName )
+import TcHsType ( tcPatSig, UserTypeCtxt(..) )
+import Inst ( newMethodFromName )
import TcEnv ( TcId, tcLookupLocalIds, tcLookupId, tcExtendIdEnv,
- tcExtendTyVarEnv )
-import TcPat ( PatCtxt(..), tcPats )
-import TcMType ( newTyFlexiVarTy, newTyFlexiVarTys, zonkTcType )
-import TcType ( TcType, TcTyVar, TcSigmaType, TcRhoType, mkFunTys,
- tyVarsOfTypes, tidyOpenTypes, isSigmaTy,
- liftedTypeKind, openTypeKind, mkFunTy, mkAppTy )
+ tcExtendTyVarEnv2 )
+import TcPat ( PatCtxt(..), tcPats, tcPat )
+import TcMType ( newFlexiTyVarTy, newFlexiTyVarTys )
+import TcType ( TcType, TcRhoType,
+ BoxySigmaType, BoxyRhoType,
+ mkFunTys, mkFunTy, mkAppTy, mkTyConApp,
+ liftedTypeKind )
import TcBinds ( tcLocalBinds )
-import TcUnify ( Expected(..), zapExpectedType, readExpectedType,
- unifyTauTy, subFunTys, unifyTyConApp,
- checkSigTyVarsWrt, zapExpectedBranches, tcSubExp, tcGen,
- unifyAppTy, zapToListTy, zapToTyConApp )
+import TcUnify ( boxySplitAppTy, boxySplitTyConApp, boxySplitListTy,
+ subFunTys, tcSubExp, withBox )
import TcSimplify ( bindInstsOfLocalFuns )
import Name ( Name )
import TysWiredIn ( stringTy, boolTy, parrTyCon, listTyCon, mkListTy, mkPArrTy )
import PrelNames ( bindMName, returnMName, mfixName, thenMName, failMName )
import Id ( idType, mkLocalId )
import TyCon ( TyCon )
-import CoreFVs ( idFreeTyVars )
-import VarSet
import Util ( isSingleton )
import Outputable
import SrcLoc ( Located(..) )
+import ErrUtils ( Message )
import List ( nub )
\end{code}
\begin{code}
tcMatchesFun :: Name
-> MatchGroup Name
- -> Expected TcRhoType -- Expected type of function
- -> TcM (MatchGroup TcId) -- Returns type of body
+ -> BoxyRhoType -- Expected type of function
+ -> TcM (ExprCoFn, MatchGroup TcId) -- Returns type of body
tcMatchesFun fun_name matches exp_ty
= do { -- Check that they all have the same no of arguments
-- 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.
- ; exp_ty' <- zapExpectedBranches matches exp_ty
- ; subFunTys ctxt matches exp_ty' $ \ pat_tys rhs_ty ->
+ ; subFunTys doc n_pats exp_ty $ \ pat_tys rhs_ty ->
tcMatches match_ctxt pat_tys rhs_ty matches
}
where
- ctxt = FunRhs fun_name
- match_ctxt = MC { mc_what = ctxt, mc_body = tcMonoExpr }
+ 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 = tcPolyExpr }
\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
- -> Expected TcRhoType -- Type of whole case expressions
+ -> BoxyRhoType -- Type of whole case expressions
-> TcM (MatchGroup TcId) -- Translated alternatives
-tcMatchesCase ctxt scrut_ty matches exp_ty
- = do { exp_ty' <- zapExpectedBranches matches exp_ty
- ; tcMatches ctxt [Check scrut_ty] exp_ty' matches }
+tcMatchesCase ctxt scrut_ty matches res_ty
+ = tcMatches ctxt [scrut_ty] res_ty matches
-tcMatchLambda :: MatchGroup Name -> Expected TcRhoType -> TcM (MatchGroup TcId)
-tcMatchLambda match exp_ty -- One branch so no unifyBranches needed
- = subFunTys LambdaExpr match exp_ty $ \ pat_tys rhs_ty ->
+tcMatchLambda :: MatchGroup Name -> BoxyRhoType -> TcM (ExprCoFn, MatchGroup TcId)
+tcMatchLambda match res_ty
+ = subFunTys doc 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),
+ -- The pprSetDepth makes the abstraction print briefly
+ ptext SLIT("has") <+> speakNOf n_pats (ptext SLIT("arguments"))]
match_ctxt = MC { mc_what = LambdaExpr,
- mc_body = tcMonoExpr }
+ mc_body = tcPolyExpr }
\end{code}
@tcGRHSsPat@ typechecks @[GRHSs]@ that occur in a @PatMonoBind@.
\begin{code}
-tcGRHSsPat :: GRHSs Name
- -> Expected TcRhoType
- -> TcM (GRHSs TcId)
-tcGRHSsPat grhss exp_ty = tcGRHSs match_ctxt grhss exp_ty
+tcGRHSsPat :: GRHSs Name -> BoxyRhoType -> TcM (GRHSs TcId)
+tcGRHSsPat grhss res_ty = tcGRHSs match_ctxt grhss res_ty
where
match_ctxt = MC { mc_what = PatBindRhs,
- mc_body = tcMonoExpr }
+ mc_body = tcPolyExpr }
\end{code}
\begin{code}
tcMatches :: TcMatchCtxt
- -> [Expected TcRhoType] -- Expected pattern types
- -> Expected TcRhoType -- Expected result-type of the Match.
+ -> [BoxySigmaType] -- Expected pattern types
+ -> BoxyRhoType -- 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
- -> Expected TcRhoType
+ -> BoxyRhoType
-> TcM (LHsExpr TcId) }
tcMatches ctxt pat_tys rhs_ty (MatchGroup matches _)
= do { matches' <- mapM (tcMatch ctxt pat_tys rhs_ty) matches
- ; pat_tys' <- mapM readExpectedType pat_tys
- ; rhs_ty' <- readExpectedType rhs_ty
- ; return (MatchGroup matches' (mkFunTys pat_tys' rhs_ty')) }
+ ; return (MatchGroup matches' (mkFunTys pat_tys rhs_ty)) }
-------------
tcMatch :: TcMatchCtxt
- -> [Expected TcRhoType] -- Expected pattern types
- -> Expected TcRhoType -- Expected result-type of the Match.
+ -> [BoxySigmaType] -- Expected pattern types
+ -> BoxyRhoType -- Expected result-type of the Match.
-> LMatch Name
-> TcM (LMatch TcId)
tcMatch ctxt pat_tys rhs_ty match
= 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') <- tcPats LamPat pats pat_tys rhs_ty $
+ tc_grhss ctxt maybe_rhs_sig grhss
+ ; returnM (Match pats' Nothing grhss') }
-tc_match ctxt pat_tys rhs_ty match@(Match pats maybe_rhs_sig grhss)
- = addErrCtxt (matchCtxt (mc_what ctxt) match) $
- do { (pats', grhss') <- tcMatchPats pats pat_tys rhs_ty $
- tc_grhss ctxt maybe_rhs_sig grhss rhs_ty
- ; returnM (Match pats' Nothing grhss') }
+ tc_grhss ctxt Nothing grhss rhs_ty
+ = tcGRHSs ctxt grhss rhs_ty -- No result signature
+ tc_grhss ctxt (Just res_sig) grhss rhs_ty
+ = do { (inner_ty, sig_tvs) <- tcPatSig ResSigCtxt res_sig rhs_ty
+ ; tcExtendTyVarEnv2 sig_tvs $
+ tcGRHSs ctxt grhss inner_ty }
-------------
-tc_grhss ctxt Nothing grhss rhs_ty
- = tcGRHSs ctxt grhss rhs_ty -- No result signature
-
-tc_grhss ctxt (Just res_sig) grhss rhs_ty
- = do { (sig_tvs, sig_ty) <- tcHsPatSigType ResSigCtxt res_sig
- ; traceTc (text "tc_grhss" <+> ppr sig_tvs)
- ; (co_fn, grhss') <- tcExtendTyVarEnv sig_tvs $
- tcThingWithSig sig_ty (tcGRHSs ctxt grhss . Check) rhs_ty
-
- -- Push the coercion down to the right hand sides,
- -- because there is no convenient place to hang it otherwise.
- ; if isIdCoercion co_fn then
- return grhss'
- else
- return (lift_grhss co_fn grhss') }
+tcGRHSs :: TcMatchCtxt -> GRHSs Name -> BoxyRhoType -> TcM (GRHSs TcId)
--------------
-lift_grhss co_fn (GRHSs grhss binds)
- = GRHSs (map (fmap lift_grhs) grhss) binds
- where
- lift_grhs (GRHS stmts rhs) = GRHS stmts (fmap (co_fn <$>) rhs)
+-- Notice that we pass in the full res_ty, so that we get
+-- good inference from simple things like
+-- f = \(x::forall a.a->a) -> <stuff>
+-- We used to force it to be a monotype when there was more than one guard
+-- but we don't need to do that any more
--------------
-tcGRHSs :: TcMatchCtxt -> GRHSs Name
- -> Expected TcRhoType
- -> TcM (GRHSs TcId)
-
- -- Special case when there is just one equation with a degenerate
- -- guard; then we pass in the full Expected type, so that we get
- -- good inference from simple things like
- -- f = \(x::forall a.a->a) -> <stuff>
- -- This is a consequence of the fact that tcStmts takes a TcType,
- -- not a Expected TcType, a decision we could revisit if necessary
-tcGRHSs ctxt (GRHSs [L loc1 (GRHS [] rhs)] binds) exp_ty
- = do { (binds', rhs') <- tcLocalBinds binds $
- mc_body ctxt rhs exp_ty
- ; returnM (GRHSs [L loc1 (GRHS [] rhs')] binds') }
-
-tcGRHSs ctxt (GRHSs grhss binds) exp_ty
- = do { exp_ty' <- zapExpectedType exp_ty openTypeKind
- -- Even if there is only one guard, we zap the RHS type to
- -- a monotype. Reason: it makes tcStmts much easier,
- -- and even a one-armed guard has a notional second arm
-
- ; (binds', grhss') <- tcLocalBinds binds $
- mappM (wrapLocM (tcGRHS ctxt exp_ty')) grhss
+tcGRHSs ctxt (GRHSs grhss binds) res_ty
+ = do { (binds', grhss') <- tcLocalBinds binds $
+ mappM (wrapLocM (tcGRHS ctxt res_ty)) grhss
; returnM (GRHSs grhss' binds') }
-------------
-tcGRHS :: TcMatchCtxt -> TcRhoType
- -> GRHS Name -> TcM (GRHS TcId)
+tcGRHS :: TcMatchCtxt -> BoxyRhoType -> GRHS Name -> TcM (GRHS TcId)
-tcGRHS ctxt exp_ty' (GRHS guards rhs)
- = do { (guards', rhs') <- tcStmts stmt_ctxt (tcGuardStmt exp_ty') guards $
- addErrCtxt (grhsCtxt match_ctxt rhs) $
- tcCheckRho rhs exp_ty'
+tcGRHS ctxt res_ty (GRHS guards rhs)
+ = do { (guards', rhs') <- tcStmts stmt_ctxt tcGuardStmt guards res_ty $
+ mc_body ctxt rhs
; return (GRHS guards' rhs') }
where
- match_ctxt = mc_what ctxt
- stmt_ctxt = PatGuard match_ctxt
-\end{code}
-
-
-\begin{code}
-tcThingWithSig :: TcSigmaType -- Type signature
- -> (TcRhoType -> TcM r) -- How to type check the thing inside
- -> Expected TcRhoType -- Overall expected result type
- -> TcM (ExprCoFn, r)
--- Used for expressions with a type signature, and for result type signatures
-
-tcThingWithSig sig_ty thing_inside res_ty
- | not (isSigmaTy sig_ty)
- = thing_inside sig_ty `thenM` \ result ->
- tcSubExp res_ty sig_ty `thenM` \ co_fn ->
- returnM (co_fn, result)
-
- | otherwise -- The signature has some outer foralls
- = -- Must instantiate the outer for-alls of sig_tc_ty
- -- else we risk instantiating a ? res_ty to a forall-type
- -- which breaks the invariant that tcMonoExpr only returns phi-types
- tcGen sig_ty emptyVarSet thing_inside `thenM` \ (gen_fn, result) ->
- tcInstCall InstSigOrigin sig_ty `thenM` \ (inst_fn, _, inst_sig_ty) ->
- tcSubExp res_ty inst_sig_ty `thenM` \ co_fn ->
- returnM (co_fn <.> inst_fn <.> gen_fn, result)
- -- Note that we generalise, then instantiate. Ah well.
-\end{code}
-
-
-%************************************************************************
-%* *
-\subsection{tcMatchPats}
-%* *
-%************************************************************************
-
-\begin{code}
-tcMatchPats :: [LPat Name]
- -> [Expected TcSigmaType] -- Pattern types
- -> Expected TcRhoType -- Result type;
- -- used only to check existential escape
- -> TcM a
- -> TcM ([LPat TcId], a)
--- Typecheck the patterns, extend the environment to bind the variables,
--- do the thing inside, use any existentially-bound dictionaries to
--- discharge parts of the returning LIE, and deal with pattern type
--- signatures
-
-tcMatchPats pats tys body_ty thing_inside
- = do { (pats', ex_tvs, res) <- tcPats LamPat pats tys thing_inside
- ; tcCheckExistentialPat pats' ex_tvs tys body_ty
- ; returnM (pats', res) }
-
-tcCheckExistentialPat :: [LPat TcId] -- Patterns (just for error message)
- -> [TcTyVar] -- Existentially quantified tyvars bound by pattern
- -> [Expected TcSigmaType] -- Types of the patterns
- -> Expected TcRhoType -- Type of the body of the match
- -- Tyvars in either of these must not escape
- -> TcM ()
- -- NB: we *must* pass "pats_tys" not just "body_ty" to tcCheckExistentialPat
- -- For example, we must reject this program:
- -- data C = forall a. C (a -> Int)
- -- f (C g) x = g x
- -- Here, result_ty will be simply Int, but expected_ty is (C -> a -> Int).
-
-tcCheckExistentialPat pats [] pat_tys body_ty
- = return () -- Short cut for case when there are no existentials
-
-tcCheckExistentialPat pats ex_tvs pat_tys body_ty
- = do { tys <- mapM readExpectedType (body_ty : pat_tys)
- ; addErrCtxtM (sigPatCtxt (collectPatsBinders pats) ex_tvs tys) $
- checkSigTyVarsWrt (tyVarsOfTypes tys) ex_tvs }
+ stmt_ctxt = PatGuard (mc_what ctxt)
\end{code}
tcDoStmts :: HsStmtContext Name
-> [LStmt Name]
-> LHsExpr Name
- -> Expected TcRhoType
+ -> BoxyRhoType
-> TcM (HsExpr TcId) -- Returns a HsDo
tcDoStmts ListComp stmts body res_ty
- = do { elt_ty <- zapToListTy res_ty
- ; (stmts', body') <- tcStmts ListComp (tcLcStmt listTyCon elt_ty) stmts $
- addErrCtxt (doBodyCtxt ListComp body) $
- tcCheckRho body elt_ty
+ = do { elt_ty <- boxySplitListTy res_ty
+ ; (stmts', body') <- tcStmts ListComp (tcLcStmt listTyCon) stmts elt_ty $
+ tcBody (doBodyCtxt ListComp body) body
; return (HsDo ListComp stmts' body' (mkListTy elt_ty)) }
tcDoStmts PArrComp stmts body res_ty
- = do { [elt_ty] <- zapToTyConApp parrTyCon res_ty
- ; (stmts', body') <- tcStmts PArrComp (tcLcStmt parrTyCon elt_ty) stmts $
- addErrCtxt (doBodyCtxt PArrComp body) $
- tcCheckRho body elt_ty
+ = do { [elt_ty] <- boxySplitTyConApp parrTyCon res_ty
+ ; (stmts', body') <- tcStmts PArrComp (tcLcStmt parrTyCon) stmts elt_ty $
+ tcBody (doBodyCtxt PArrComp body) body
; return (HsDo PArrComp stmts' body' (mkPArrTy elt_ty)) }
tcDoStmts DoExpr stmts body res_ty
- = do { res_ty' <- zapExpectedType res_ty liftedTypeKind
- ; (m_ty, _) <- unifyAppTy res_ty'
- ; (stmts', body') <- tcStmts DoExpr (tcDoStmt m_ty res_ty') stmts $
- addErrCtxt (doBodyCtxt DoExpr body) $
- tcCheckRho 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 res_ty' $
+ tcBody (doBodyCtxt DoExpr body) body
; return (HsDo DoExpr stmts' body' res_ty') }
-tcDoStmts cxt@(MDoExpr _) stmts body res_ty
- = do { res_ty' <- zapExpectedType res_ty liftedTypeKind
- ; (m_ty, _) <- unifyAppTy res_ty'
- ; let tc_rhs rhs = do { (rhs', rhs_ty) <- tcInferRho rhs
- ; (n_ty, pat_ty) <- unifyAppTy rhs_ty
- ; unifyTauTy m_ty n_ty
- ; return (rhs', pat_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 cxt (tcMDoStmt res_ty' tc_rhs) stmts $
- addErrCtxt (doBodyCtxt cxt body) $
- tcCheckRho body res_ty'
+ ; (stmts', body') <- tcStmts ctxt (tcMDoStmt tc_rhs) stmts res_ty' $
+ tcBody (doBodyCtxt ctxt body) 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 :: Message -> LHsExpr Name -> BoxyRhoType -> TcM (LHsExpr TcId)
+tcBody ctxt body res_ty
+ = -- addErrCtxt ctxt $ -- This context adds little that is useful
+ tcPolyExpr body res_ty
\end{code}
type TcStmtChecker
= forall thing. HsStmtContext Name
-> Stmt Name
- -> TcM thing
+ -> BoxyRhoType -- Result type for comprehension
+ -> (BoxyRhoType -> 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]
- -> TcM thing
+ -> BoxyRhoType
+ -> (BoxyRhoType -> 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 [] thing_inside
- = do { thing <- thing_inside
+tcStmts ctxt stmt_chk [] 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) thing_inside
+tcStmts ctxt stmt_chk (L loc (LetStmt binds) : stmts) res_ty thing_inside
= do { (binds', (stmts',thing)) <- tcLocalBinds binds $
- tcStmts ctxt stmt_chk stmts thing_inside
+ tcStmts 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) thing_inside
+tcStmts 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 $
- popErrCtxt $
- tcStmts ctxt stmt_chk stmts $
+ setSrcSpan loc $
+ addErrCtxt (stmtCtxt ctxt stmt) $
+ stmt_chk ctxt stmt res_ty $ \ res_ty' ->
+ popErrCtxt $
+ tcStmts ctxt stmt_chk stmts res_ty' $
thing_inside
; return (L loc stmt' : stmts', thing) }
--------------------------------
-- Pattern guards
-tcGuardStmt :: TcType -> TcStmtChecker
-tcGuardStmt res_ty ctxt (ExprStmt guard _ _) thing_inside
- = do { guard' <- tcCheckRho guard boolTy
- ; thing <- thing_inside
+tcGuardStmt :: TcStmtChecker
+tcGuardStmt ctxt (ExprStmt guard _ _) res_ty thing_inside
+ = do { guard' <- tcMonoExpr guard boolTy
+ ; thing <- thing_inside res_ty
; return (ExprStmt guard' noSyntaxExpr boolTy, thing) }
-tcGuardStmt res_ty ctxt (BindStmt pat rhs _ _) thing_inside
+tcGuardStmt ctxt (BindStmt pat rhs _ _) res_ty thing_inside
= do { (rhs', rhs_ty) <- tcInferRho rhs
- ; (pat', thing) <- tcBindPat pat rhs_ty res_ty thing_inside
+ ; (pat', thing) <- tcPat LamPat pat rhs_ty res_ty thing_inside
; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
-tcGuardStmt res_ty ctxt stmt thing_inside
+tcGuardStmt ctxt stmt res_ty thing_inside
= pprPanic "tcGuardStmt: unexpected Stmt" (ppr stmt)
-- List comprehensions and PArrays
tcLcStmt :: TyCon -- The list/Parray type constructor ([] or PArray)
- -> TcType -- The element type of the list or PArray
-> TcStmtChecker
-- A generator, pat <- rhs
-tcLcStmt m_tc elt_ty ctxt (BindStmt pat rhs _ _) thing_inside
- = do { (rhs', rhs_ty) <- tcInferRho rhs
- ; [pat_ty] <- unifyTyConApp m_tc rhs_ty
- ; (pat', thing) <- tcBindPat pat pat_ty elt_ty thing_inside
+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) <- tcPat LamPat pat pat_ty res_ty thing_inside
; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
-- A boolean guard
-tcLcStmt m_tc elt_ty ctxt (ExprStmt rhs _ _) thing_inside
- = do { rhs' <- tcCheckRho rhs boolTy
- ; thing <- thing_inside
+tcLcStmt m_tc ctxt (ExprStmt rhs _ _) res_ty thing_inside
+ = do { rhs' <- tcMonoExpr rhs boolTy
+ ; thing <- thing_inside res_ty
; return (ExprStmt rhs' noSyntaxExpr boolTy, thing) }
-- A parallel set of comprehensions
-- 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 elt_ty ctxt (ParStmt bndr_stmts_s) 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) }
where
-- loop :: [([LStmt Name], [Name])] -> TcM ([([LStmt TcId], [TcId])], thing)
- loop [] = do { thing <- thing_inside
- ; return ([], thing) }
+ loop [] = do { thing <- thing_inside elt_ty -- No refinement from pattern
+ ; return ([], thing) } -- matching in the branches
loop ((stmts, names) : pairs)
= do { (stmts', (ids, pairs', thing))
- <- tcStmts ctxt (tcLcStmt m_tc elt_ty) stmts $
+ <- tcStmts 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 elt_ty ctxt stmt thing_inside
+tcLcStmt m_tc ctxt stmt elt_ty thing_inside
= pprPanic "tcLcStmt: unexpected Stmt" (ppr stmt)
--------------------------------
-- The main excitement here is dealing with rebindable syntax
tcDoStmt :: TcType -- Monad type, m
- -> TcType -- Result type, m b
-> TcStmtChecker
- -- BindStmt
-tcDoStmt m_ty res_ty ctxt (BindStmt pat rhs bind_op fail_op) thing_inside
- = do { -- Deal with rebindable syntax; (>>=) :: m a -> (a -> m b) -> m b
- ; (rhs', rhs_ty) <- tcInferRho rhs
+
+tcDoStmt m_ty ctxt (BindStmt pat rhs bind_op fail_op) 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
-- We do inference on rhs, so that information about its type can be refined
-- when type-checking the pattern.
- ; (n_ty, pat_ty) <- unifyAppTy rhs_ty
- ; unifyTauTy m_ty n_ty
- ; let bind_ty = mkFunTys [rhs_ty, mkFunTy pat_ty res_ty] res_ty
-
- ; (pat', thing) <- tcBindPat pat pat_ty res_ty thing_inside
+ ; (pat', thing) <- tcPat LamPat pat pat_ty res_ty thing_inside
- -- Rebindable syntax stuff
+ -- 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
; return (BindStmt pat' rhs' bind_op' fail_op', thing) }
-tcDoStmt m_ty res_ty ctxt (ExprStmt rhs then_op _) thing_inside
+tcDoStmt m_ty ctxt (ExprStmt rhs then_op _) res_ty thing_inside
= do { -- Deal with rebindable syntax; (>>) :: m a -> m b -> m b
- a_ty <- newTyFlexiVarTy liftedTypeKind
+ 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' <- tcCheckSigma rhs rhs_ty
- ; thing <- thing_inside
+ ; rhs' <- tcPolyExpr rhs rhs_ty
+ ; thing <- thing_inside res_ty
; return (ExprStmt rhs' then_op' rhs_ty, thing) }
-tcDoStmt m_ty res_ty ctxt stmt thing_inside
+tcDoStmt m_ty ctxt stmt res_ty thing_inside
= pprPanic "tcDoStmt: unexpected Stmt" (ppr stmt)
--------------------------------
-- (a) RecStmts, and
-- (b) no rebindable syntax
-tcMDoStmt :: TcType -- Result type, m b
- -> (LHsExpr Name -> TcM (LHsExpr TcId, TcType)) -- RHS inference
+tcMDoStmt :: (LHsExpr Name -> TcM (LHsExpr TcId, TcType)) -- RHS inference
-> TcStmtChecker
-tcMDoStmt res_ty tc_rhs ctxt (BindStmt pat rhs bind_op fail_op) thing_inside
+tcMDoStmt tc_rhs ctxt (BindStmt pat rhs bind_op fail_op) res_ty thing_inside
= do { (rhs', pat_ty) <- tc_rhs rhs
- ; (pat', thing) <- tcBindPat pat pat_ty res_ty thing_inside
+ ; (pat', thing) <- tcPat LamPat pat pat_ty res_ty thing_inside
; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
-tcMDoStmt res_ty tc_rhs ctxt (ExprStmt rhs then_op _) thing_inside
+tcMDoStmt tc_rhs ctxt (ExprStmt rhs then_op _) res_ty thing_inside
= do { (rhs', elt_ty) <- tc_rhs rhs
- ; thing <- thing_inside
+ ; thing <- thing_inside res_ty
; return (ExprStmt rhs' noSyntaxExpr elt_ty, thing) }
-tcMDoStmt res_ty tc_rhs ctxt (RecStmt stmts laterNames recNames _ _) thing_inside
- = do { rec_tys <- newTyFlexiVarTys (length recNames) liftedTypeKind
+tcMDoStmt tc_rhs ctxt (RecStmt stmts laterNames recNames _ _) res_ty thing_inside
+ = do { rec_tys <- newFlexiTyVarTys (length recNames) liftedTypeKind
; let rec_ids = zipWith mkLocalId recNames rec_tys
; tcExtendIdEnv rec_ids $ do
{ (stmts', (later_ids, rec_rets))
- <- tcStmts ctxt (tcMDoStmt res_ty tc_rhs) stmts $
+ <- tcStmts ctxt (tcMDoStmt tc_rhs) stmts res_ty $ \ res_ty' ->
-- ToDo: res_ty not really right
do { rec_rets <- zipWithM tc_ret recNames rec_tys
; later_ids <- tcLookupLocalIds laterNames
; return (later_ids, rec_rets) }
- ; (thing,lie) <- tcExtendIdEnv later_ids (getLIE thing_inside)
+ ; (thing,lie) <- tcExtendIdEnv later_ids (getLIE (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
where
-- Unify the types of the "final" Ids with those of "knot-tied" Ids
tc_ret rec_name mono_ty
- = tcLookupId rec_name `thenM` \ poly_id ->
+ = do { poly_id <- tcLookupId rec_name
-- poly_id may have a polymorphic type
-- but mono_ty is just a monomorphic type variable
- tcSubExp (Check mono_ty) (idType poly_id) `thenM` \ co_fn ->
- returnM (co_fn <$> HsVar poly_id)
+ ; co_fn <- tcSubExp (idType poly_id) mono_ty
+ ; return (HsCoerce co_fn (HsVar poly_id)) }
-tcMDoStmt res_ty tc_rhs ctxt stmt thing_inside
+tcMDoStmt tc_rhs ctxt stmt res_ty thing_inside
= pprPanic "tcMDoStmt: unexpected Stmt" (ppr stmt)
------------------
-tcBindPat :: LPat Name -> TcType
- -> TcType -- Result type; used only to check existential escape
- -> TcM a
- -> TcM (LPat TcId, a)
-tcBindPat pat pat_ty res_ty thing_inside
- = do { ([pat'],thing) <- tcMatchPats [pat] [Check pat_ty]
- (Check res_ty) thing_inside
- ; return (pat', thing) }
\end{code}
matchCtxt ctxt match = hang (ptext SLIT("In") <+> pprMatchContext ctxt <> colon)
4 (pprMatch ctxt match)
-grhsCtxt ctxt rhs = hang (ptext SLIT("In") <+> pprMatchRhsContext ctxt <> colon)
- 4 (ppr rhs)
-
doBodyCtxt :: HsStmtContext Name -> LHsExpr Name -> SDoc
doBodyCtxt ctxt body = hang (ptext SLIT("In the result of") <+> pprStmtContext ctxt <> colon)
4 (ppr body)
stmtCtxt ctxt stmt = hang (ptext SLIT("In") <+> pprStmtContext ctxt <> colon)
4 (ppr stmt)
-
-sigPatCtxt bound_ids bound_tvs tys tidy_env
- = -- tys is (body_ty : pat_tys)
- mapM zonkTcType tys `thenM` \ tys' ->
- let
- (env1, tidy_tys) = tidyOpenTypes tidy_env (map idType show_ids)
- (_env2, tidy_body_ty : tidy_pat_tys) = tidyOpenTypes env1 tys'
- in
- returnM (env1,
- sep [ptext SLIT("When checking an existential match that binds"),
- nest 4 (vcat (zipWith ppr_id show_ids tidy_tys)),
- ptext SLIT("The pattern(s) have type(s):") <+> vcat (map ppr tidy_pat_tys),
- ptext SLIT("The body has type:") <+> ppr tidy_body_ty
- ])
- where
- show_ids = filter is_interesting bound_ids
- is_interesting id = any (`elemVarSet` idFreeTyVars id) bound_tvs
-
- ppr_id id ty = ppr id <+> dcolon <+> ppr ty
- -- Don't zonk the types so we get the separate, un-unified versions
\end{code}
projects / ghc-hetmet.git / blobdiff