import {-# SOURCE #-} TcExpr( tcExpr )
import HsSyn ( HsBinds(..), Match(..), GRHSs(..), GRHS(..),
- MonoBinds(..), Stmt(..), HsMatchContext(..),
+ MonoBinds(..), Stmt(..), HsMatchContext(..), HsDoContext(..),
pprMatch, getMatchLoc, pprMatchContext, isDoExpr,
mkMonoBind, nullMonoBinds, collectSigTysFromPats
)
-import RnHsSyn ( RenamedMatch, RenamedGRHSs, RenamedStmt )
-import TcHsSyn ( TcMatch, TcGRHSs, TcStmt, TcDictBinds )
+import RnHsSyn ( RenamedMatch, RenamedGRHSs, RenamedStmt, RenamedPat, RenamedHsType,
+ RenamedMatchContext, extractHsTyVars )
+import TcHsSyn ( TcMatch, TcGRHSs, TcStmt, TcDictBinds, TypecheckedPat, TypecheckedMatchContext )
import TcMonad
-import TcMonoType ( kcHsSigType, tcTyVars, checkSigTyVars, tcHsSigType, sigPatCtxt )
+import TcMonoType ( kcHsSigTypes, tcScopedTyVars, checkSigTyVars, tcHsSigType, sigPatCtxt )
import Inst ( LIE, isEmptyLIE, plusLIE, emptyLIE, plusLIEs, lieToList )
-import TcEnv ( TcId, tcLookupLocalIds, tcExtendTyVarEnv, tcExtendLocalValEnv, tcExtendGlobalTyVars )
+import TcEnv ( TcId, tcLookupLocalIds, tcExtendLocalValEnv, tcExtendGlobalTyVars,
+ tcInLocalScope )
import TcPat ( tcPat, tcMonoPatBndr, polyPatSig )
import TcType ( TcType, newTyVarTy )
import TcBinds ( tcBindsAndThen )
import TcSimplify ( tcSimplifyCheck, bindInstsOfLocalFuns )
import TcUnify ( unifyFunTy, unifyTauTy )
import Name ( Name )
-import TysWiredIn ( boolTy, mkListTy )
+import TysWiredIn ( boolTy )
import Id ( idType )
import BasicTypes ( RecFlag(..) )
import Type ( tyVarsOfType, isTauTy, mkFunTy,
liftedTypeKind, openTypeKind, splitSigmaTy )
+import NameSet
import VarSet
import Var ( Id )
import Bag
-- may show up as something wrong with the (non-existent) type signature
-- No need to zonk expected_ty, because unifyFunTy does that on the fly
- tcMatches xve matches expected_ty (FunRhs fun_name)
+ tcMatches xve (FunRhs fun_name) matches expected_ty
\end{code}
@tcMatchesCase@ doesn't do the argument-count check because the
tcMatchesCase matches expr_ty
= newTyVarTy openTypeKind `thenNF_Tc` \ scrut_ty ->
- tcMatches [] matches (mkFunTy scrut_ty expr_ty) CaseAlt `thenTc` \ (matches', lie) ->
+ tcMatches [] CaseAlt matches (mkFunTy scrut_ty expr_ty) `thenTc` \ (matches', lie) ->
returnTc (scrut_ty, matches', lie)
tcMatchLambda :: RenamedMatch -> TcType -> TcM (TcMatch, LIE)
-tcMatchLambda match res_ty = tcMatch [] match res_ty LambdaExpr
+tcMatchLambda match res_ty = tcMatch [] LambdaExpr match res_ty
\end{code}
\begin{code}
tcMatches :: [(Name,Id)]
+ -> RenamedMatchContext
-> [RenamedMatch]
-> TcType
- -> HsMatchContext
-> TcM ([TcMatch], LIE)
-tcMatches xve matches expected_ty fun_or_case
+tcMatches xve fun_or_case matches expected_ty
= mapAndUnzipTc tc_match matches `thenTc` \ (matches, lies) ->
returnTc (matches, plusLIEs lies)
where
- tc_match match = tcMatch xve match expected_ty fun_or_case
+ tc_match match = tcMatch xve fun_or_case match expected_ty
\end{code}
\begin{code}
tcMatch :: [(Name,Id)]
+ -> RenamedMatchContext
-> RenamedMatch
-> TcType -- Expected result-type of the Match.
-- Early unification with this guy gives better error messages
- -> HsMatchContext
-> TcM (TcMatch, LIE)
-tcMatch xve1 match@(Match sig_tvs pats maybe_rhs_sig grhss) expected_ty ctxt
- = tcAddSrcLoc (getMatchLoc match) $
- tcAddErrCtxt (matchCtxt ctxt match) $
+tcMatch xve1 ctxt match@(Match sig_tvs pats maybe_rhs_sig grhss) expected_ty
+ = tcAddSrcLoc (getMatchLoc match) $ -- At one stage I removed this;
+ tcAddErrCtxt (matchCtxt ctxt match) $ -- I'm not sure why, so I put it back
+
+ tcMatchPats pats expected_ty tc_grhss `thenTc` \ ((pats', grhss'), lie, ex_binds) ->
+ returnTc (Match [] pats' Nothing (glue_on Recursive ex_binds grhss'), lie)
- if null sig_tvs then -- The common case
- tc_match expected_ty `thenTc` \ (_, match_and_lie) ->
- returnTc match_and_lie
-
- else
- -- If there are sig tvs we must be careful *not* to use
- -- expected_ty right away, else we'll unify with tyvars free
- -- in the envt. So invent a fresh tyvar and use that instead
- newTyVarTy openTypeKind `thenNF_Tc` \ tyvar_ty ->
+ where
+ tc_grhss pats' rhs_ty
+ = -- Check that the remaining "expected type" is not a rank-2 type
+ -- If it is it'll mess up the unifier when checking the RHS
+ checkTc (isTauTy rhs_ty) lurkingRank2SigErr `thenTc_`
- -- Extend the tyvar env and check the match itself
- tcTyVars sig_tvs (mapTc_ kcHsSigType sig_tys) `thenTc` \ sig_tyvars ->
- tcExtendTyVarEnv sig_tyvars (tc_match tyvar_ty) `thenTc` \ (pat_ids, match_and_lie) ->
+ -- Deal with the result signature
+ tc_result_sig maybe_rhs_sig (
- -- Check that the scoped type variables from the patterns
- -- have not been constrained
- tcAddErrCtxtM (sigPatCtxt sig_tyvars pat_ids) (
- checkSigTyVars sig_tyvars emptyVarSet
- ) `thenTc_`
+ -- Typecheck the body
+ tcExtendLocalValEnv xve1 $
+ tcGRHSs ctxt grhss rhs_ty `thenTc` \ (grhss', lie) ->
+ returnTc ((pats', grhss'), lie)
+ )
- -- *Now* we're free to unify with expected_ty
- unifyTauTy expected_ty tyvar_ty `thenTc_`
+ tc_result_sig Nothing thing_inside
+ = thing_inside
+ tc_result_sig (Just sig) thing_inside
+ = tcAddScopedTyVars [sig] $
+ tcHsSigType sig `thenTc` \ sig_ty ->
- returnTc match_and_lie
+ -- Check that the signature isn't a polymorphic one, which
+ -- we don't permit (at present, anyway)
+ checkTc (isTauTy sig_ty) (polyPatSig sig_ty) `thenTc_`
+ unifyTauTy expected_ty sig_ty `thenTc_`
+ thing_inside
- where
- sig_tys = case maybe_rhs_sig of { Just t -> [t]; Nothing -> [] }
- ++ collectSigTysFromPats pats
-
- tc_match expected_ty -- Any sig tyvars are in scope by now
- = -- STEP 1: Typecheck the patterns
- tcMatchPats pats expected_ty `thenTc` \ (rhs_ty, pats', lie_req1, ex_tvs, pat_bndrs, lie_avail) ->
- let
- xve2 = bagToList pat_bndrs
- pat_ids = map snd xve2
- in
-
- -- STEP 2: Check that the remaining "expected type" is not a rank-2 type
- -- If it is it'll mess up the unifier when checking the RHS
- checkTc (isTauTy rhs_ty) lurkingRank2SigErr `thenTc_`
-
- -- STEP 3: Unify with the rhs type signature if any
- (case maybe_rhs_sig of
- Nothing -> returnTc ()
- Just sig -> tcHsSigType sig `thenTc` \ sig_ty ->
-
- -- Check that the signature isn't a polymorphic one, which
- -- we don't permit (at present, anyway)
- checkTc (isTauTy sig_ty) (polyPatSig sig_ty) `thenTc_`
- unifyTauTy rhs_ty sig_ty
- ) `thenTc_`
-
- -- STEP 4: Typecheck the guarded RHSs and the associated where clause
- tcExtendLocalValEnv xve1 (tcExtendLocalValEnv xve2 (
- tcGRHSs grhss rhs_ty ctxt
- )) `thenTc` \ (grhss', lie_req2) ->
-
- -- STEP 5: Check for existentially bound type variables
- tcCheckExistentialPat pat_ids ex_tvs lie_avail
- (lie_req1 `plusLIE` lie_req2)
- rhs_ty `thenTc` \ (lie_req', ex_binds) ->
-
- -- Phew! All done.
- let
- match' = Match [] pats' Nothing (glue_on Recursive ex_binds grhss')
- in
- returnTc (pat_ids, (match', lie_req'))
-- glue_on just avoids stupid dross
glue_on _ EmptyMonoBinds grhss = grhss -- The common case
glue_on is_rec mbinds (GRHSs grhss binds ty)
= GRHSs grhss (mkMonoBind mbinds [] is_rec `ThenBinds` binds) ty
-tcGRHSs :: RenamedGRHSs
- -> TcType -> HsMatchContext
+tcGRHSs :: RenamedMatchContext -> RenamedGRHSs
+ -> TcType
-> TcM (TcGRHSs, LIE)
-tcGRHSs (GRHSs grhss binds _) expected_ty ctxt
+tcGRHSs ctxt (GRHSs grhss binds _) expected_ty
= tcBindsAndThen glue_on binds (tc_grhss grhss)
where
tc_grhss grhss
= tcAddSrcLoc locn $
tcStmts ctxt (\ty -> ty, expected_ty) guarded `thenTc` \ (guarded', lie) ->
returnTc (GRHS guarded' locn, lie)
+\end{code}
+%************************************************************************
+%* *
+\subsection{tcMatchPats}
+%* *
+%************************************************************************
+
+\begin{code}
+tcMatchPats
+ :: [RenamedPat] -> TcType
+ -> ([TypecheckedPat] -> TcType -> TcM (a, LIE))
+ -> TcM (a, LIE, TcDictBinds)
+-- 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 expected_ty thing_inside
+ = -- STEP 1: Bring pattern-signature type variables into scope
+ tcAddScopedTyVars (collectSigTysFromPats pats) $
+
+ -- STEP 2: Typecheck the patterns themselves, gathering all the stuff
+ tc_match_pats pats expected_ty `thenTc` \ (rhs_ty, pats', lie_req1, ex_tvs, pat_bndrs, lie_avail) ->
+
+ -- STEP 3: Extend the environment, and do the thing inside
+ let
+ xve = bagToList pat_bndrs
+ pat_ids = map snd xve
+ in
+ tcExtendLocalValEnv xve (thing_inside pats' rhs_ty) `thenTc` \ (result, lie_req2) ->
+
+ -- STEP 4: Check for existentially bound type variables
+ -- I'm a bit concerned that lie_req1 from an 'inner' pattern in the list
+ -- might need (via lie_req2) something made available from an 'outer'
+ -- pattern. But it's inconvenient to deal with, and I can't find an example
+ tcCheckExistentialPat pat_ids ex_tvs lie_avail lie_req2 rhs_ty `thenTc` \ (lie_req2', ex_binds) ->
+
+ returnTc (result, lie_req1 `plusLIE` lie_req2', ex_binds)
+
+tcAddScopedTyVars :: [RenamedHsType] -> TcM a -> TcM a
+-- Find the not-already-in-scope signature type variables,
+-- kind-check them, and bring them into scope
+--
+-- We no longer specify that these type variables must be univerally
+-- quantified (lots of email on the subject). If you want to put that
+-- back in, you need to
+-- a) Do a checkSigTyVars after thing_inside
+-- b) More insidiously, don't pass in expected_ty, else
+-- we unify with it too early and checkSigTyVars barfs
+-- Instead you have to pass in a fresh ty var, and unify
+-- it with expected_ty afterwards
+tcAddScopedTyVars sig_tys thing_inside
+ = tcGetEnv `thenNF_Tc` \ env ->
+ let
+ all_sig_tvs = foldr (unionNameSets . extractHsTyVars) emptyNameSet sig_tys
+ sig_tvs = filter not_in_scope (nameSetToList all_sig_tvs)
+ not_in_scope tv = not (tcInLocalScope env tv)
+ in
+ tcScopedTyVars sig_tvs (kcHsSigTypes sig_tys) thing_inside
+
tcCheckExistentialPat :: [TcId] -- Ids bound by this pattern
-> Bag TcTyVar -- Existentially quantified tyvars bound by pattern
-> LIE -- and context
tv_list = bagToList ex_tvs
not_overloaded id = case splitSigmaTy (idType id) of
(_, theta, _) -> null theta
-\end{code}
-
-
-%************************************************************************
-%* *
-\subsection{tcMatchPats}
-%* *
-%************************************************************************
-\begin{code}
-tcMatchPats [] expected_ty
+tc_match_pats [] expected_ty
= returnTc (expected_ty, [], emptyLIE, emptyBag, emptyBag, emptyLIE)
-tcMatchPats (pat:pats) expected_ty
+tc_match_pats (pat:pats) expected_ty
= unifyFunTy expected_ty `thenTc` \ (arg_ty, rest_ty) ->
tcPat tcMonoPatBndr pat arg_ty `thenTc` \ (pat', lie_req, pat_tvs, pat_ids, lie_avail) ->
- tcMatchPats pats rest_ty `thenTc` \ (rhs_ty, pats', lie_reqs, pats_tvs, pats_ids, lie_avails) ->
+ tc_match_pats pats rest_ty `thenTc` \ (rhs_ty, pats', lie_reqs, pats_tvs, pats_ids, lie_avails) ->
returnTc ( rhs_ty,
pat':pats',
lie_req `plusLIE` lie_reqs,
tcStmtsAndThen
:: (TcStmt -> thing -> thing) -- Combiner
- -> HsMatchContext
+ -> RenamedMatchContext
-> (TcType -> TcType, TcType) -- m, the relationship type of pat and rhs in pat <- rhs
-- elt_ty, where type of the comprehension is (m elt_ty)
-> [RenamedStmt]
tcStmtsAndThen combine do_or_lc m_ty [] do_next
= do_next
+tcStmtsAndThen combine do_or_lc m_ty (stmt:stmts) do_next
+ = tcStmtAndThen combine do_or_lc m_ty stmt
+ (tcStmtsAndThen combine do_or_lc m_ty stmts do_next)
+
-- LetStmt
-tcStmtsAndThen combine do_or_lc m_ty (LetStmt binds : stmts) do_next
+tcStmtAndThen combine do_or_lc m_ty (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
- (tcStmtsAndThen combine do_or_lc m_ty stmts do_next)
-
- -- BindStmt
-tcStmtsAndThen combine do_or_lc m_ty@(m,elt_ty) (stmt@(BindStmt pat exp src_loc) : stmts) do_next
- = tcAddSrcLoc src_loc (
- tcSetErrCtxt (stmtCtxt do_or_lc stmt) $
- newTyVarTy liftedTypeKind `thenNF_Tc` \ pat_ty ->
- tcPat tcMonoPatBndr pat pat_ty `thenTc` \ (pat', pat_lie, pat_tvs, pat_ids, avail) ->
- tcExpr exp (m pat_ty) `thenTc` \ (exp', exp_lie) ->
- returnTc (pat', exp',
- pat_lie `plusLIE` exp_lie,
- pat_tvs, pat_ids, avail)
- ) `thenTc` \ (pat', exp', lie_req, pat_tvs, pat_bndrs, lie_avail) ->
- let
- new_val_env = bagToList pat_bndrs
- pat_ids = map snd new_val_env
- in
-
- -- Do the rest; we don't need to add the pat_tvs to the envt
- -- because they all appear in the pat_ids's types
- tcExtendLocalValEnv new_val_env (
- tcStmtsAndThen combine do_or_lc m_ty stmts do_next
- ) `thenTc` \ (thing, stmts_lie) ->
-
- -- Reinstate context for existential checks
- tcSetErrCtxt (stmtCtxt do_or_lc stmt) $
- tcCheckExistentialPat pat_ids pat_tvs lie_avail
- stmts_lie (m elt_ty) `thenTc` \ (final_lie, dict_binds) ->
-
- returnTc (combine (BindStmt pat' exp' src_loc)
- (glue_binds combine Recursive dict_binds thing),
- lie_req `plusLIE` final_lie)
+ thing_inside
+
+tcStmtAndThen combine do_or_lc m_ty@(m,elt_ty) stmt@(BindStmt pat exp src_loc) thing_inside
+ = tcAddSrcLoc src_loc $
+ tcAddErrCtxt (stmtCtxt do_or_lc stmt) $
+ newTyVarTy liftedTypeKind `thenNF_Tc` \ pat_ty ->
+ tcExpr exp (m pat_ty) `thenTc` \ (exp', exp_lie) ->
+ tcMatchPats [pat] (mkFunTy pat_ty (m elt_ty)) (\ [pat'] _ ->
+ tcPopErrCtxt $
+ thing_inside `thenTc` \ (thing, lie) ->
+ returnTc ((BindStmt pat' exp' src_loc, thing), lie)
+ ) `thenTc` \ ((stmt', thing), lie, dict_binds) ->
+ returnTc (combine stmt' (glue_binds combine Recursive dict_binds thing),
+ lie `plusLIE` exp_lie)
-- ParStmt
-tcStmtsAndThen combine do_or_lc m_ty (ParStmtOut bndr_stmts_s : stmts) do_next
+tcStmtAndThen combine do_or_lc m_ty (ParStmtOut bndr_stmts_s) thing_inside
= loop bndr_stmts_s `thenTc` \ ((pairs', thing), lie) ->
returnTc (combine (ParStmtOut pairs') thing, lie)
where
loop []
- = tcStmtsAndThen combine do_or_lc m_ty stmts do_next `thenTc` \ (thing, stmts_lie) ->
+ = thing_inside `thenTc` \ (thing, stmts_lie) ->
returnTc (([], thing), stmts_lie)
loop ((bndrs,stmts) : pairs)
= tcStmtsAndThen
- combine_par ListComp (mkListTy, not_required) stmts
+ combine_par (DoCtxt ListComp) m_ty stmts
+ -- Notice we pass on m_ty; the result type is used only
+ -- to get escaping type variables for checkExistentialPat
(tcLookupLocalIds bndrs `thenNF_Tc` \ bndrs' ->
loop pairs `thenTc` \ ((pairs', thing), lie) ->
returnTc (([], (bndrs', pairs', thing)), lie)) `thenTc` \ ((stmts', (bndrs', pairs', thing)), lie) ->
returnTc ( ((bndrs',stmts') : pairs', thing), lie)
combine_par stmt (stmts, thing) = (stmt:stmts, thing)
- not_required = panic "tcStmtsAndThen: elt_ty"
- -- The simple-statment case
-tcStmtsAndThen combine do_or_lc m_ty (stmt@(ExprStmt exp locn):stmts) do_next
+ -- ExprStmt
+tcStmtAndThen combine do_or_lc m_ty@(m, res_elt_ty) stmt@(ExprStmt exp locn) thing_inside
= tcSetErrCtxt (stmtCtxt do_or_lc stmt) (
- tcExprStmt do_or_lc m_ty exp (null stmts)
- ) `thenTc` \ (exp', stmt_lie) ->
+ if isDoExpr do_or_lc then
+ newTyVarTy openTypeKind `thenNF_Tc` \ any_ty ->
+ tcExpr exp (m any_ty)
+ else
+ tcExpr exp boolTy
+ ) `thenTc` \ (exp', stmt_lie) ->
- tcStmtsAndThen combine do_or_lc m_ty stmts do_next `thenTc` \ (thing, stmts_lie) ->
+ thing_inside `thenTc` \ (thing, stmts_lie) ->
returnTc (combine (ExprStmt exp' locn) thing,
stmt_lie `plusLIE` stmts_lie)
-------------------------------
- -- ExprStmt; see comments with HsExpr.HsStmt
- -- for meaning of ExprStmt
-tcExprStmt do_or_lc (m, res_elt_ty) exp is_last_stmt
- = compute_expr_ty `thenNF_Tc` \ expr_ty ->
- tcExpr exp expr_ty
- where
- compute_expr_ty
- | is_last_stmt = if isDoExpr do_or_lc then
- returnNF_Tc (m res_elt_ty)
- else
- returnNF_Tc res_elt_ty
-
- | otherwise = if isDoExpr do_or_lc then
- newTyVarTy openTypeKind `thenNF_Tc` \ any_ty ->
- returnNF_Tc (m any_ty)
- else
- returnNF_Tc boolTy
+ -- Result statements
+tcStmtAndThen combine do_or_lc m_ty@(m, res_elt_ty) stmt@(ResultStmt exp locn) thing_inside
+ = tcSetErrCtxt (stmtCtxt do_or_lc stmt) (
+ if isDoExpr do_or_lc then
+ tcExpr exp (m res_elt_ty)
+ else
+ tcExpr exp res_elt_ty
+ ) `thenTc` \ (exp', stmt_lie) ->
+
+ thing_inside `thenTc` \ (thing, stmts_lie) ->
+
+ returnTc (combine (ResultStmt exp' locn) thing,
+ stmt_lie `plusLIE` stmts_lie)
+
------------------------------
glue_binds combine is_rec binds thing
\end{code}
\begin{code}
-matchCtxt CaseAlt match
- = hang (ptext SLIT("In a case alternative:"))
- 4 (pprMatch (True,empty) {-is_case-} match)
-
-matchCtxt (FunRhs fun) match
- = hang (hcat [ptext SLIT("In an equation for function "), quotes (ppr_fun), char ':'])
- 4 (pprMatch (False, ppr_fun) {-not case-} match)
- where
- ppr_fun = ppr fun
-
-matchCtxt LambdaExpr match
- = hang (ptext SLIT("In the lambda expression"))
- 4 (pprMatch (True, empty) match)
+matchCtxt ctxt match = hang (pprMatchContext ctxt <> colon) 4 (pprMatch ctxt match)
+stmtCtxt do_or_lc stmt = hang (pprMatchContext do_or_lc <> colon) 4 (ppr stmt)
varyingArgsErr name matches
= sep [ptext SLIT("Varying number of arguments for function"), quotes (ppr name)]
lurkingRank2SigErr
= ptext SLIT("Too few explicit arguments when defining a function with a rank-2 type")
-
-stmtCtxt do_or_lc stmt = hang (pprMatchContext do_or_lc <> colon) 4 (ppr stmt)
\end{code}
projects / ghc-hetmet.git / blobdiff