\section[TcMatches]{Typecheck some @Matches@}
\begin{code}
-module TcMatches ( tcMatchesFun, tcMatchesCase, tcMatchLambda, matchCtxt,
- tcDoStmts, tcStmtsAndThen, tcStmts, tcGRHSs, tcThingWithSig,
+module TcMatches ( tcMatchesFun, tcGRHSsPat, tcMatchesCase, tcMatchLambda,
+ matchCtxt,
+ tcDoStmts, tcStmtsAndThen, tcStmts, tcThingWithSig,
tcMatchPats,
- TcStmtCtxt(..)
+ TcStmtCtxt(..), TcMatchCtxt(..)
) where
#include "HsVersions.h"
import {-# SOURCE #-} TcExpr( tcCheckRho, tcMonoExpr )
-import HsSyn ( HsExpr(..), HsBinds(..), Match(..), GRHSs(..), GRHS(..),
- MonoBinds(..), Stmt(..), HsMatchContext(..), HsStmtContext(..),
- ReboundNames,
- pprMatch, getMatchLoc, isDoExpr,
+import HsSyn ( HsExpr(..), LHsExpr, HsBindGroup(..),
+ Match(..), LMatch, GRHSs(..), GRHS(..),
+ Stmt(..), LStmt, HsMatchContext(..), HsStmtContext(..),
+ ReboundNames, LPat,
+ pprMatch, isDoExpr,
pprMatchContext, pprStmtContext, pprStmtResultContext,
- mkMonoBind, collectSigTysFromPats, andMonoBindList, glueBindsOnGRHSs
+ collectSigTysFromPats, glueBindsOnGRHSs
)
-import RnHsSyn ( RenamedMatch, RenamedGRHSs, RenamedStmt, RenamedHsExpr,
- RenamedPat, RenamedMatchContext )
-import TcHsSyn ( TcMatch, TcGRHSs, TcStmt, TcDictBinds, TcHsBinds, TcExpr,
- TcMonoBinds, TcPat, TcStmt, ExprCoFn,
- isIdCoercion, (<$>), (<.>) )
+import TcHsSyn ( ExprCoFn, TcDictBinds, isIdCoercion, (<$>), (<.>) )
import TcRnMonad
-import TcMonoType ( tcAddScopedTyVars, tcHsSigType, UserTypeCtxt(..) )
+import TcHsType ( tcAddScopedTyVars, tcHsSigType, UserTypeCtxt(..) )
import Inst ( tcSyntaxName, tcInstCall )
import TcEnv ( TcId, tcLookupLocalIds, tcLookupId, tcExtendLocalValEnv, tcExtendLocalValEnv2 )
import TcPat ( tcPat, tcMonoPatBndr )
import TcMType ( newTyVarTy, newTyVarTys, zonkTcType )
import TcType ( TcType, TcTyVar, TcSigmaType, TcRhoType,
- tyVarsOfTypes, tidyOpenTypes, tidyOpenType, isSigmaTy,
+ tyVarsOfTypes, tidyOpenTypes, isSigmaTy, typeKind,
mkFunTy, isOverloadedTy, liftedTypeKind, openTypeKind,
mkArrowKind, mkAppTy )
import TcBinds ( tcBindsAndThen )
checkSigTyVarsWrt, tcSubExp, tcGen )
import TcSimplify ( tcSimplifyCheck, bindInstsOfLocalFuns )
import Name ( Name )
-import PrelNames ( monadNames, mfixName )
import TysWiredIn ( boolTy, mkListTy, mkPArrTy )
-import Id ( idType, mkSysLocal, mkLocalId )
+import Id ( idType, mkLocalId )
import CoreFVs ( idFreeTyVars )
import BasicTypes ( RecFlag(..) )
import VarSet
-import Var ( Id )
import Bag
-import Util ( isSingleton, notNull, zipEqual )
+import Util ( isSingleton, notNull )
import Outputable
+import SrcLoc ( Located(..), noLoc )
import List ( nub )
\end{code}
\begin{code}
tcMatchesFun :: Name
- -> [RenamedMatch]
+ -> [LMatch Name]
-> Expected TcRhoType -- Expected type
- -> TcM [TcMatch]
+ -> TcM [LMatch TcId]
tcMatchesFun fun_name matches@(first_match:_) expected_ty
= -- Check that they all have the same no of arguments
- -- Set the location to that of the first equation, so that
+ -- 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...
- addSrcLoc (getMatchLoc first_match) (
- checkTc (sameNoOfArgs matches)
- (varyingArgsErr fun_name matches)
- ) `thenM_`
+ checkTc (sameNoOfArgs matches)
+ (varyingArgsErr fun_name matches) `thenM_`
-- 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
-- No need to zonk expected_ty, because subFunTys does that on the fly
- tcMatches (FunRhs fun_name) matches expected_ty
+ tcMatches match_ctxt matches expected_ty
+ where
+ match_ctxt = MC { mc_what = FunRhs fun_name,
+ mc_body = tcMonoExpr }
\end{code}
@tcMatchesCase@ doesn't do the argument-count check because the
parser guarantees that each equation has exactly one argument.
\begin{code}
-tcMatchesCase :: [RenamedMatch] -- The case alternatives
+tcMatchesCase :: TcMatchCtxt -- Case context
+ -> [LMatch Name] -- The case alternatives
-> Expected TcRhoType -- Type of whole case expressions
-> TcM (TcRhoType, -- Inferred type of the scrutinee
- [TcMatch]) -- Translated alternatives
-
-tcMatchesCase matches (Check expr_ty)
- = -- This case is a bit yukky, because it prevents the
- -- scrutinee being higher-ranked, which might just possible
- -- matter if we were seq'ing on it. But it's awkward to fix.
- newTyVarTy openTypeKind `thenM` \ scrut_ty ->
- tcMatches CaseAlt matches (Check (mkFunTy scrut_ty expr_ty)) `thenM` \ matches' ->
+ [LMatch TcId]) -- Translated alternatives
+
+tcMatchesCase ctxt matches (Check expr_ty)
+ = newTyVarTy openTypeKind `thenM` \ scrut_ty ->
+ -- openTypeKind because the scrutinee can be an unboxed type
+ tcMatches ctxt matches (Check (mkFunTy scrut_ty expr_ty)) `thenM` \ matches' ->
returnM (scrut_ty, matches')
-tcMatchesCase matches (Infer hole)
+tcMatchesCase ctxt matches (Infer hole)
= newHole `thenM` \ fun_hole ->
- tcMatches CaseAlt matches (Infer fun_hole) `thenM` \ matches' ->
+ tcMatches ctxt matches (Infer fun_hole) `thenM` \ matches' ->
readMutVar fun_hole `thenM` \ fun_ty ->
-- The result of tcMatches is bound to be a function type
unifyFunTy fun_ty `thenM` \ (scrut_ty, res_ty) ->
returnM (scrut_ty, matches')
-tcMatchLambda :: RenamedMatch -> Expected TcRhoType -> TcM TcMatch
-tcMatchLambda match res_ty = tcMatch LambdaExpr match res_ty
+tcMatchLambda :: LMatch Name -> Expected TcRhoType -> TcM (LMatch TcId)
+tcMatchLambda match res_ty = tcMatch match_ctxt res_ty match
+ where
+ match_ctxt = MC { mc_what = LambdaExpr,
+ mc_body = tcMonoExpr }
\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
+ where
+ match_ctxt = MC { mc_what = PatBindRhs,
+ mc_body = tcMonoExpr }
+\end{code}
\begin{code}
-tcMatches :: RenamedMatchContext
- -> [RenamedMatch]
+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
+ -> TcM (LHsExpr TcId) }
+
+tcMatches :: TcMatchCtxt
+ -> [LMatch Name]
-> Expected TcRhoType
- -> TcM [TcMatch]
+ -> TcM [LMatch TcId]
tcMatches ctxt matches exp_ty
= -- If there is more than one branch, and exp_ty is a 'hole',
-- all branches must be types, not type schemes, otherwise the
-- order in which we check them would affect the result.
zapExpectedBranches matches exp_ty `thenM` \ exp_ty' ->
- mappM (tc_match exp_ty') matches
- where
- tc_match exp_ty match = tcMatch ctxt match exp_ty
+ mappM (tcMatch ctxt exp_ty') matches
\end{code}
%************************************************************************
\begin{code}
-tcMatch :: RenamedMatchContext
- -> RenamedMatch
+tcMatch :: TcMatchCtxt
-> Expected TcRhoType -- Expected result-type of the Match.
-- Early unification with this guy gives better error messages
-- We regard the Match as having type
-- (ty1 -> ... -> tyn -> result_ty)
-- where there are n patterns.
- -> TcM TcMatch
+ -> LMatch Name
+ -> TcM (LMatch TcId)
-tcMatch ctxt match@(Match pats maybe_rhs_sig grhss) expected_ty
- = addSrcLoc (getMatchLoc match) $ -- At one stage I removed this;
- addErrCtxt (matchCtxt ctxt match) $ -- I'm not sure why, so I put it back
+tcMatch ctxt exp_ty match = wrapLocM (tc_match ctxt exp_ty) match
+
+tc_match ctxt expected_ty match@(Match pats maybe_rhs_sig grhss)
+ = addErrCtxt (matchCtxt (mc_what ctxt) match) $ -- I'm not sure why, so I put it back
subFunTys pats expected_ty $ \ pats_w_tys rhs_ty ->
-- This is the unique place we call subFunTys
-- The point is that if expected_y is a "hole", we want
returnM (lift_grhss co_fn rhs_ty' grhss')
lift_grhss co_fn rhs_ty (GRHSs grhss binds ty)
- = GRHSs (map lift_grhs grhss) binds rhs_ty -- Change the type, since the coercion does
+ = GRHSs (map (fmap lift_grhs) grhss) binds rhs_ty -- Change the type, since the coercion does
where
- lift_grhs (GRHS stmts loc) = GRHS (map lift_stmt stmts) loc
+ lift_grhs (GRHS stmts) = GRHS (map lift_stmt stmts)
- lift_stmt (ResultStmt e l) = ResultStmt (co_fn <$> e) l
- lift_stmt stmt = stmt
-
-tcGRHSs :: RenamedMatchContext -> RenamedGRHSs
+ lift_stmt (L loc (ResultStmt e)) = L loc (ResultStmt (fmap (co_fn <$>) e))
+ lift_stmt stmt = stmt
+
+tcGRHSs :: TcMatchCtxt -> GRHSs Name
-> Expected TcRhoType
- -> TcM TcGRHSs
+ -> 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
-- 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 [GRHS [ResultStmt rhs loc1] loc2] binds _) exp_ty
+tcGRHSs ctxt (GRHSs [L loc1 (GRHS [L loc2 (ResultStmt rhs)])] binds _) exp_ty
= tcBindsAndThen glueBindsOnGRHSs binds $
- tcMonoExpr rhs exp_ty `thenM` \ rhs' ->
+ mc_body ctxt rhs exp_ty `thenM` \ rhs' ->
readExpectedType exp_ty `thenM` \ exp_ty' ->
- returnM (GRHSs [GRHS [ResultStmt rhs' loc1] loc2] EmptyBinds exp_ty')
+ returnM (GRHSs [L loc1 (GRHS [L loc2 (ResultStmt rhs')])] [] exp_ty')
tcGRHSs ctxt (GRHSs grhss binds _) exp_ty
= tcBindsAndThen glueBindsOnGRHSs binds $
- zapExpectedType exp_ty `thenM` \ exp_ty' ->
+ zapExpectedType exp_ty openTypeKind `thenM` \ exp_ty' ->
-- 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
let
- stmt_ctxt = SC { sc_what = PatGuard ctxt,
+ stmt_ctxt = SC { sc_what = PatGuard (mc_what ctxt),
sc_rhs = tcCheckRho,
- sc_body = \ body -> tcCheckRho body exp_ty',
+ sc_body = sc_body,
sc_ty = exp_ty' }
+ sc_body body = mc_body ctxt body (Check exp_ty')
- tc_grhs (GRHS guarded locn)
- = addSrcLoc locn $
- tcStmts stmt_ctxt guarded `thenM` \ guarded' ->
- returnM (GRHS guarded' locn)
+ tc_grhs (GRHS guarded)
+ = tcStmts stmt_ctxt guarded `thenM` \ guarded' ->
+ returnM (GRHS guarded')
in
- mappM tc_grhs grhss `thenM` \ grhss' ->
- returnM (GRHSs grhss' EmptyBinds exp_ty')
+ mappM (wrapLocM tc_grhs) grhss `thenM` \ grhss' ->
+ returnM (GRHSs grhss' [] exp_ty')
\end{code}
\begin{code}
tcMatchPats
- :: [(RenamedPat, Expected TcRhoType)]
+ :: [(LPat Name, Expected TcRhoType)]
-> Expected TcRhoType
-> TcM a
- -> TcM ([TcPat], a, TcHsBinds)
+ -> TcM ([LPat TcId], a, HsBindGroup TcId)
-- 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
-- f (C g) x = g x
-- Here, result_ty will be simply Int, but expected_ty is (C -> a -> Int).
- returnM (pats', result, mkMonoBind Recursive ex_binds)
+ returnM (pats', result, HsBindGroup ex_binds [] Recursive)
tc_match_pats [] thing_inside
= thing_inside `thenM` \ answer ->
-- of the existential Ids used in checkExistentialPat
in
tcExtendLocalValEnv2 xve $
+ traceTc (text "tc_match_pats" <+> (ppr xve $$ ppr (map (idType . snd) xve) $$
+ ppr (map (typeKind . idType . snd) xve))) `thenM_`
tc_match_pats pats thing_inside `thenM` \ (pats', exs_tvs, exs_ids, exs_lie, answer) ->
returnM ( pat':pats',
ex_tvs `unionBags` exs_tvs,
-- Here we must discharge op Methods
= ASSERT( null ex_lie )
extendLIEs lie_req `thenM_`
- returnM EmptyMonoBinds
+ returnM emptyBag
| otherwise
= -- Read the by-now-filled-in expected types
-- Check for type variable escape
checkSigTyVarsWrt (tyVarsOfTypes tys) tv_list `thenM_`
- returnM (dict_binds `AndMonoBinds` inst_binds)
+ returnM (dict_binds `unionBags` inst_binds)
where
doc = text ("existential context of a data constructor")
tv_list = bagToList ex_tvs
\begin{code}
tcDoStmts :: HsStmtContext Name
- -> [RenamedStmt] -> ReboundNames Name
+ -> [LStmt Name] -> ReboundNames Name
-> TcRhoType -- To keep it simple, we don't have an "expected" type here
- -> TcM ([TcStmt], ReboundNames TcId)
+ -> TcM ([LStmt TcId], ReboundNames TcId)
tcDoStmts PArrComp stmts method_names res_ty
= unifyPArrTy res_ty `thenM` \elt_ty ->
tcComprehension PArrComp mkPArrTy elt_ty stmts `thenM` \ stmts' ->
tcStmtsAndThen (:) ctxt stmts (returnM [])
data TcStmtCtxt
- = SC { sc_what :: HsStmtContext Name, -- What kind of thing this is
- sc_rhs :: RenamedHsExpr -> TcType -> TcM TcExpr, -- Type checker for RHS computations
- sc_body :: RenamedHsExpr -> TcM TcExpr, -- Type checker for return computation
+ = SC { sc_what :: HsStmtContext Name, -- What kind of thing this is
+ sc_rhs :: LHsExpr Name -> TcType -> TcM (LHsExpr TcId), -- Type checker for RHS computations
+ sc_body :: LHsExpr Name -> TcM (LHsExpr TcId), -- Type checker for return computation
sc_ty :: TcType } -- Return type; used *only* to check
-- for escape in existential patterns
tcStmtsAndThen
- :: (TcStmt -> thing -> thing) -- Combiner
+ :: (LStmt TcId -> thing -> thing) -- Combiner
-> TcStmtCtxt
- -> [RenamedStmt]
+ -> [LStmt Name]
-> TcM thing
-> TcM thing
thing_inside
-- LetStmt
-tcStmtAndThen combine ctxt (LetStmt binds) thing_inside
+tcStmtAndThen combine ctxt (L _ (LetStmt binds)) thing_inside
= tcBindsAndThen -- No error context, but a binding group is
(glue_binds combine) -- rather a large thing for an error context anyway
binds
thing_inside
-- BindStmt
-tcStmtAndThen combine ctxt stmt@(BindStmt pat exp src_loc) thing_inside
- = addSrcLoc src_loc $
+tcStmtAndThen combine ctxt (L src_loc stmt@(BindStmt pat exp)) thing_inside
+ = addSrcSpan src_loc $
addErrCtxt (stmtCtxt ctxt stmt) $
newTyVarTy liftedTypeKind `thenM` \ pat_ty ->
sc_rhs ctxt exp pat_ty `thenM` \ exp' ->
tcMatchPats [(pat, Check pat_ty)] (Check (sc_ty ctxt)) (
popErrCtxt thing_inside
) `thenM` \ ([pat'], thing, dict_binds) ->
- returnM (combine (BindStmt pat' exp' src_loc)
+ returnM (combine (L src_loc (BindStmt pat' exp'))
(glue_binds combine dict_binds thing))
-- ExprStmt
-tcStmtAndThen combine ctxt stmt@(ExprStmt exp _ src_loc) thing_inside
- = addSrcLoc src_loc (
+tcStmtAndThen combine ctxt (L src_loc stmt@(ExprStmt exp _)) thing_inside
+ = addSrcSpan src_loc (
addErrCtxt (stmtCtxt ctxt stmt) $
if isDoExpr (sc_what ctxt)
then -- do or mdo; the expression is a computation
- newTyVarTy openTypeKind `thenM` \ any_ty ->
+ newTyVarTy liftedTypeKind `thenM` \ any_ty ->
sc_rhs ctxt exp any_ty `thenM` \ exp' ->
- returnM (ExprStmt exp' any_ty src_loc)
+ returnM (L src_loc (ExprStmt exp' any_ty))
else -- List comprehensions, pattern guards; expression is a boolean
tcCheckRho exp boolTy `thenM` \ exp' ->
- returnM (ExprStmt exp' boolTy src_loc)
+ returnM (L src_loc (ExprStmt exp' boolTy))
) `thenM` \ stmt' ->
thing_inside `thenM` \ thing ->
-- ParStmt
-tcStmtAndThen combine ctxt (ParStmt bndr_stmts_s) thing_inside
+tcStmtAndThen combine ctxt (L src_loc (ParStmt bndr_stmts_s)) thing_inside
= loop bndr_stmts_s `thenM` \ (pairs', thing) ->
- returnM (combine (ParStmt pairs') thing)
+ returnM (combine (L src_loc (ParStmt pairs')) thing)
where
loop [] = thing_inside `thenM` \ thing ->
returnM ([], thing)
combine_par stmt ((stmts, bndrs) : pairs , thing) = ((stmt:stmts, bndrs) : pairs, thing)
-- RecStmt
-tcStmtAndThen combine ctxt (RecStmt stmts laterNames recNames _) thing_inside
+tcStmtAndThen combine ctxt (L src_loc (RecStmt stmts laterNames recNames _)) thing_inside
= newTyVarTys (length recNames) liftedTypeKind `thenM` \ recTys ->
let
rec_ids = zipWith mkLocalId recNames recTys
in
tcExtendLocalValEnv rec_ids $
tcStmtsAndThen combine_rec ctxt stmts (
- mappM tc_ret (recNames `zip` recTys) `thenM` \ rec_rets ->
+ zipWithM tc_ret recNames recTys `thenM` \ rec_rets ->
tcLookupLocalIds laterNames `thenM` \ later_ids ->
returnM ([], (later_ids, rec_rets))
) `thenM` \ (stmts', (later_ids, rec_rets)) ->
-- already scope over this part
thing_inside `thenM` \ thing ->
- returnM (combine (RecStmt stmts' later_ids rec_ids rec_rets) thing)
+ returnM (combine (L src_loc (RecStmt stmts' later_ids rec_ids rec_rets)) thing)
where
combine_rec stmt (stmts, thing) = (stmt:stmts, thing)
-- Unify the types of the "final" Ids with those of "knot-tied" Ids
- tc_ret (rec_name, mono_ty)
+ tc_ret rec_name mono_ty
= tcLookupId rec_name `thenM` \ poly_id ->
-- 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 <$> HsVar poly_id)
+ returnM (L src_loc (co_fn <$> HsVar poly_id))
-- Result statements
-tcStmtAndThen combine ctxt stmt@(ResultStmt exp locn) thing_inside
+tcStmtAndThen combine ctxt (L src_loc stmt@(ResultStmt exp)) thing_inside
= addErrCtxt (stmtCtxt ctxt stmt) (sc_body ctxt exp) `thenM` \ exp' ->
thing_inside `thenM` \ thing ->
- returnM (combine (ResultStmt exp' locn) thing)
+ returnM (combine (L src_loc (ResultStmt exp')) thing)
------------------------------
-glue_binds combine EmptyBinds thing = thing
-glue_binds combine other_binds thing = combine (LetStmt other_binds) thing
+glue_binds combine binds thing = combine (noLoc (LetStmt [binds])) thing
+ -- ToDo: fix the noLoc
\end{code}
number of args are used in each equation.
\begin{code}
-sameNoOfArgs :: [RenamedMatch] -> Bool
+sameNoOfArgs :: [LMatch Name] -> Bool
sameNoOfArgs matches = isSingleton (nub (map args_in_match matches))
where
- args_in_match :: RenamedMatch -> Int
- args_in_match (Match pats _ _) = length pats
+ args_in_match :: LMatch Name -> Int
+ args_in_match (L _ (Match pats _ _)) = length pats
\end{code}
\begin{code}
stmtCtxt ctxt stmt = hang (ptext SLIT("In") <+> pp_ctxt (sc_what ctxt) <> colon) 4 (ppr stmt)
where
pp_ctxt = case stmt of
- ResultStmt _ _ -> pprStmtResultContext
- other -> pprStmtContext
+ ResultStmt _ -> pprStmtResultContext
+ other -> pprStmtContext
sigPatCtxt bound_tvs bound_ids 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'
+ (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"),
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