\begin{code}
module TcMatches ( tcMatchesFun, tcMatchesCase, tcMatchLambda,
- tcStmts, tcStmtsAndThen, tcGRHSs
+ tcDoStmts, tcStmtsAndThen, tcGRHSs
) where
#include "HsVersions.h"
-import {-# SOURCE #-} TcExpr( tcExpr )
+import {-# SOURCE #-} TcExpr( tcMonoExpr )
-import HsSyn ( HsBinds(..), Match(..), GRHSs(..), GRHS(..),
- MonoBinds(..), Stmt(..), HsMatchContext(..), HsDoContext(..),
- pprMatch, getMatchLoc, pprMatchContext, isDoExpr,
- mkMonoBind, nullMonoBinds, collectSigTysFromPats
+import HsSyn ( HsExpr(..), HsBinds(..), Match(..), GRHSs(..), GRHS(..),
+ MonoBinds(..), Stmt(..), HsMatchContext(..), HsStmtContext(..),
+ pprMatch, getMatchLoc, isDoExpr,
+ pprMatchContext, pprStmtContext, pprStmtResultContext,
+ mkMonoBind, collectSigTysFromPats, andMonoBindList
)
-import RnHsSyn ( RenamedMatch, RenamedGRHSs, RenamedStmt, RenamedPat, RenamedMatchContext )
-import TcHsSyn ( TcMatch, TcGRHSs, TcStmt, TcDictBinds, TypecheckedPat )
+import RnHsSyn ( RenamedMatch, RenamedGRHSs, RenamedStmt,
+ RenamedPat, RenamedMatchContext )
+import TcHsSyn ( TcMatch, TcGRHSs, TcStmt, TcDictBinds, TcHsBinds,
+ TcMonoBinds, TcPat, TcStmt )
-import TcMonad
+import TcRnMonad
import TcMonoType ( tcAddScopedTyVars, tcHsSigType, UserTypeCtxt(..) )
-import Inst ( LIE, isEmptyLIE, plusLIE, emptyLIE, plusLIEs, lieToList )
-import TcEnv ( TcId, tcLookupLocalIds, tcExtendLocalValEnv, tcExtendGlobalTyVars )
-import TcPat ( tcPat, tcMonoPatBndr, polyPatSig )
-import TcMType ( newTyVarTy )
-import TcType ( TcType, TcTyVar, tyVarsOfType,
- mkFunTy, isOverloadedTy, liftedTypeKind, openTypeKind )
+import Inst ( tcSyntaxName )
+import TcEnv ( TcId, tcLookupLocalIds, tcLookupId, tcExtendLocalValEnv, tcExtendLocalValEnv2 )
+import TcPat ( tcPat, tcMonoPatBndr )
+import TcMType ( newTyVarTy, newTyVarTys, zonkTcType, zapToType )
+import TcType ( TcType, TcTyVar, tyVarsOfType, tidyOpenTypes, tidyOpenType,
+ mkFunTy, isOverloadedTy, liftedTypeKind, openTypeKind,
+ mkArrowKind, mkAppTy )
import TcBinds ( tcBindsAndThen )
-import TcUnify ( subFunTy, checkSigTyVars, tcSub, isIdCoercion, (<$>), sigPatCtxt )
+import TcUnify ( unifyPArrTy,subFunTy, unifyListTy, unifyTauTy,
+ checkSigTyVarsWrt, tcSubExp, isIdCoercion, (<$>) )
import TcSimplify ( tcSimplifyCheck, bindInstsOfLocalFuns )
import Name ( Name )
-import TysWiredIn ( boolTy )
-import Id ( idType )
+import PrelNames ( monadNames, mfixName )
+import TysWiredIn ( boolTy, mkListTy, mkPArrTy )
+import Id ( idType, mkSysLocal, mkLocalId )
+import CoreFVs ( idFreeTyVars )
import BasicTypes ( RecFlag(..) )
import VarSet
import Var ( Id )
import Bag
-import Util ( isSingleton )
+import Util ( isSingleton, lengthExceeds, notNull, zipEqual )
import Outputable
import List ( nub )
-> Name
-> TcType -- Expected type
-> [RenamedMatch]
- -> TcM ([TcMatch], LIE)
+ -> TcM [TcMatch]
tcMatchesFun xve fun_name expected_ty matches@(first_match:_)
= -- Check that they all have the same no of arguments
-- sensible location. Note: we have to do this odd
-- ann-grabbing, because we don't always have annotations in
-- hand when we call tcMatchesFun...
- tcAddSrcLoc (getMatchLoc first_match) (
+ addSrcLoc (getMatchLoc first_match) (
checkTc (sameNoOfArgs matches)
(varyingArgsErr fun_name matches)
- ) `thenTc_`
+ ) `thenM_`
-- ToDo: Don't use "expected" stuff if there ain't a type signature
-- because inconsistency between branches
tcMatchesCase :: [RenamedMatch] -- The case alternatives
-> TcType -- Type of whole case expressions
-> TcM (TcType, -- Inferred type of the scrutinee
- [TcMatch], -- Translated alternatives
- LIE)
+ [TcMatch]) -- Translated alternatives
tcMatchesCase matches expr_ty
- = newTyVarTy openTypeKind `thenNF_Tc` \ scrut_ty ->
- tcMatches [] CaseAlt matches (mkFunTy scrut_ty expr_ty) `thenTc` \ (matches', lie) ->
- returnTc (scrut_ty, matches', lie)
+ = newTyVarTy openTypeKind `thenM` \ scrut_ty ->
+ tcMatches [] CaseAlt matches (mkFunTy scrut_ty expr_ty) `thenM` \ matches' ->
+ returnM (scrut_ty, matches')
-tcMatchLambda :: RenamedMatch -> TcType -> TcM (TcMatch, LIE)
+tcMatchLambda :: RenamedMatch -> TcType -> TcM TcMatch
tcMatchLambda match res_ty = tcMatch [] LambdaExpr match res_ty
\end{code}
-> RenamedMatchContext
-> [RenamedMatch]
-> TcType
- -> TcM ([TcMatch], LIE)
-
-tcMatches xve fun_or_case matches expected_ty
- = mapAndUnzipTc tc_match matches `thenTc` \ (matches, lies) ->
- returnTc (matches, plusLIEs lies)
+ -> TcM [TcMatch]
+
+tcMatches xve ctxt matches expected_ty
+ = -- If there is more than one branch, and expected_ty is a 'hole',
+ -- all branches must be types, not type schemes, otherwise the
+ -- in which we check them would affect the result.
+ (if lengthExceeds matches 1 then
+ zapToType expected_ty
+ else
+ returnM expected_ty) `thenM` \ expected_ty' ->
+
+ mappM (tc_match expected_ty') matches
where
- tc_match match = tcMatch xve fun_or_case match expected_ty
+ tc_match expected_ty match = tcMatch xve ctxt match expected_ty
\end{code}
-- We regard the Match as having type
-- (ty1 -> ... -> tyn -> result_ty)
-- where there are n patterns.
- -> TcM (TcMatch, LIE)
+ -> TcM TcMatch
tcMatch xve1 ctxt match@(Match 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)
+ = addSrcLoc (getMatchLoc match) $ -- At one stage I removed this;
+ addErrCtxt (matchCtxt ctxt match) $ -- I'm not sure why, so I put it back
+ tcMatchPats pats expected_ty tc_grhss `thenM` \ (pats', grhss', ex_binds) ->
+ returnM (Match pats' Nothing (glue_on ex_binds grhss'))
where
- tc_grhss pats' rhs_ty
- = tcExtendLocalValEnv xve1 $
+ tc_grhss rhs_ty
+ = tcExtendLocalValEnv2 xve1 $
-- Deal with the result signature
case maybe_rhs_sig of
- Nothing -> tcGRHSs ctxt grhss rhs_ty `thenTc` \ (grhss', lie) ->
- returnTc ((pats', grhss'), lie)
+ Nothing -> tcGRHSs ctxt grhss rhs_ty
Just sig -> tcAddScopedTyVars [sig] $
-- Bring into scope the type variables in the signature
- tcHsSigType ResSigCtxt sig `thenTc` \ sig_ty ->
- tcGRHSs ctxt grhss sig_ty `thenTc` \ (grhss', lie1) ->
- tcSub rhs_ty sig_ty `thenTc` \ (co_fn, lie2) ->
- returnTc ((pats', lift_grhss co_fn rhs_ty grhss'),
- lie1 `plusLIE` lie2)
+ tcHsSigType ResSigCtxt sig `thenM` \ sig_ty ->
+ tcGRHSs ctxt grhss sig_ty `thenM` \ grhss' ->
+ tcSubExp rhs_ty sig_ty `thenM` \ co_fn ->
+ returnM (lift_grhss co_fn rhs_ty grhss')
-- lift_grhss pushes the coercion down to the right hand sides,
-- because there is no convenient place to hang it otherwise.
lift_stmt stmt = stmt
-- 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
+glue_on EmptyBinds grhss = grhss -- The common case
+glue_on binds1 (GRHSs grhss binds2 ty)
+ = GRHSs grhss (binds1 `ThenBinds` binds2) ty
tcGRHSs :: RenamedMatchContext -> RenamedGRHSs
-> TcType
- -> TcM (TcGRHSs, LIE)
+ -> TcM TcGRHSs
tcGRHSs ctxt (GRHSs grhss binds _) expected_ty
= tcBindsAndThen glue_on binds (tc_grhss grhss)
where
+ m_ty = (\ty -> ty, expected_ty)
+
tc_grhss grhss
- = mapAndUnzipTc tc_grhs grhss `thenTc` \ (grhss', lies) ->
- returnTc (GRHSs grhss' EmptyBinds expected_ty, plusLIEs lies)
+ = mappM tc_grhs grhss `thenM` \ grhss' ->
+ returnM (GRHSs grhss' EmptyBinds expected_ty)
tc_grhs (GRHS guarded locn)
- = tcAddSrcLoc locn $
- tcStmts ctxt (\ty -> ty, expected_ty) guarded `thenTc` \ (guarded', lie) ->
- returnTc (GRHS guarded' locn, lie)
+ = addSrcLoc locn $
+ tcStmts (PatGuard ctxt) m_ty guarded `thenM` \ guarded' ->
+ returnM (GRHS guarded' locn)
\end{code}
\begin{code}
tcMatchPats
:: [RenamedPat] -> TcType
- -> ([TypecheckedPat] -> TcType -> TcM (a, LIE))
- -> TcM (a, LIE, TcDictBinds)
+ -> (TcType -> TcM a)
+ -> TcM ([TcPat], a, TcHsBinds)
-- 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
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) ->
-
- returnTc (rhs_ty, lie_req1, ex_tvs, pat_ids, lie_avail, result, lie_req2)
- ) `thenTc` \ (rhs_ty, lie_req1, ex_tvs, pat_ids, lie_avail, result, lie_req2) ->
+ -- then do the thing inside
+ getLIE (tc_match_pats pats expected_ty thing_inside)
+
+ ) `thenM` \ ((pats', ex_tvs, ex_ids, ex_lie, result), lie_req) ->
-- STEP 4: Check for existentially bound type variables
-- Do this *outside* the scope of the tcAddScopedTyVars, else checkSigTyVars
-- 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 expected_ty `thenTc` \ (lie_req2', ex_binds) ->
+ tcCheckExistentialPat ex_tvs ex_ids ex_lie lie_req expected_ty `thenM` \ ex_binds ->
-- NB: we *must* pass "expected_ty" not "result_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 (a -> Int).
- returnTc (result, lie_req1 `plusLIE` lie_req2', ex_binds)
+ returnM (pats', result, mkMonoBind Recursive ex_binds)
+
+tc_match_pats [] expected_ty thing_inside
+ = thing_inside expected_ty `thenM` \ answer ->
+ returnM ([], emptyBag, [], [], answer)
+
+tc_match_pats (pat:pats) expected_ty thing_inside
+ = subFunTy expected_ty $ \ arg_ty rest_ty ->
+ -- This is the unique place we call subFunTy
+ -- The point is that if expected_y is a "hole", we want
+ -- to make arg_ty and rest_ty as "holes" too.
+ tcPat tcMonoPatBndr pat arg_ty `thenM` \ (pat', ex_tvs, pat_bndrs, ex_lie) ->
+ let
+ xve = bagToList pat_bndrs
+ ex_ids = [id | (_, id) <- xve]
+ -- ex_ids is all the pattern-bound Ids, a superset
+ -- of the existential Ids used in checkExistentialPat
+ in
+ tcExtendLocalValEnv2 xve $
+ tc_match_pats pats rest_ty thing_inside `thenM` \ (pats', exs_tvs, exs_ids, exs_lie, answer) ->
+ returnM ( pat':pats',
+ ex_tvs `unionBags` exs_tvs,
+ ex_ids ++ exs_ids,
+ ex_lie ++ exs_lie,
+ answer
+ )
+
-tcCheckExistentialPat :: [TcId] -- Ids bound by this pattern
- -> Bag TcTyVar -- Existentially quantified tyvars bound by pattern
- -> LIE -- and context
- -> LIE -- Required context
+tcCheckExistentialPat :: Bag TcTyVar -- Existentially quantified tyvars bound by pattern
+ -> [TcId] -- Ids bound by this pattern; used
+ -- (a) by bindsInstsOfLocalFuns
+ -- (b) to generate helpful error messages
+ -> [Inst] -- and context
+ -> [Inst] -- Required context
-> TcType -- and type of the Match; vars in here must not escape
- -> TcM (LIE, TcDictBinds) -- LIE to float out and dict bindings
-tcCheckExistentialPat ids ex_tvs lie_avail lie_req match_ty
- | isEmptyBag ex_tvs && all not_overloaded ids
+ -> TcM TcDictBinds -- LIE to float out and dict bindings
+tcCheckExistentialPat ex_tvs ex_ids ex_lie lie_req match_ty
+ | isEmptyBag ex_tvs && all not_overloaded ex_ids
-- Short cut for case when there are no existentials
-- and no polymorphic overloaded variables
-- e.g. f :: (forall a. Ord a => a -> a) -> Int -> Int
-- f op x = ....
-- Here we must discharge op Methods
- = ASSERT( isEmptyLIE lie_avail )
- returnTc (lie_req, EmptyMonoBinds)
+ = ASSERT( null ex_lie )
+ extendLIEs lie_req `thenM_`
+ returnM EmptyMonoBinds
| otherwise
- = tcExtendGlobalTyVars (tyVarsOfType match_ty) $
- tcAddErrCtxtM (sigPatCtxt tv_list ids) $
+ = addErrCtxtM (sigPatCtxt tv_list ex_ids match_ty) $
-- In case there are any polymorpic, overloaded binders in the pattern
-- (which can happen in the case of rank-2 type signatures, or data constructors
-- with polymorphic arguments), we must do a bindInstsOfLocalFns here
- bindInstsOfLocalFuns lie_req ids `thenTc` \ (lie1, inst_binds) ->
+ getLIE (bindInstsOfLocalFuns lie_req ex_ids) `thenM` \ (inst_binds, lie) ->
-- Deal with overloaded functions bound by the pattern
- tcSimplifyCheck doc tv_list (lieToList lie_avail) lie1 `thenTc` \ (lie2, dict_binds) ->
- checkSigTyVars tv_list emptyVarSet `thenTc_`
+ tcSimplifyCheck doc tv_list ex_lie lie `thenM` \ dict_binds ->
+ checkSigTyVarsWrt (tyVarsOfType match_ty) tv_list `thenM_`
- returnTc (lie2, dict_binds `AndMonoBinds` inst_binds)
+ returnM (dict_binds `AndMonoBinds` inst_binds)
where
- doc = text ("the existential context of a data constructor")
+ doc = text ("existential context of a data constructor")
tv_list = bagToList ex_tvs
not_overloaded id = not (isOverloadedTy (idType id))
+\end{code}
-tc_match_pats [] expected_ty
- = returnTc (expected_ty, [], emptyLIE, emptyBag, emptyBag, emptyLIE)
-tc_match_pats (pat:pats) expected_ty
- = subFunTy expected_ty `thenTc` \ (arg_ty, rest_ty) ->
- -- This is the unique place we call subFunTy
- -- The point is that if expected_y is a "hole", we want
- -- to make arg_ty and rest_ty as "holes" too.
- tcPat tcMonoPatBndr pat arg_ty `thenTc` \ (pat', lie_req, pat_tvs, pat_ids, lie_avail) ->
- 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,
- pat_tvs `unionBags` pats_tvs,
- pat_ids `unionBags` pats_ids,
- lie_avail `plusLIE` lie_avails
- )
+%************************************************************************
+%* *
+\subsection{@tcDoStmts@ typechecks a {\em list} of do statements}
+%* *
+%************************************************************************
+
+\begin{code}
+tcDoStmts :: HsStmtContext Name -> [RenamedStmt] -> [Name] -> TcType
+ -> TcM (TcMonoBinds, [TcStmt], [Id])
+tcDoStmts PArrComp stmts method_names res_ty
+ = unifyPArrTy res_ty `thenM` \elt_ty ->
+ tcStmts PArrComp (mkPArrTy, elt_ty) stmts `thenM` \ stmts' ->
+ returnM (EmptyMonoBinds, stmts', [{- unused -}])
+
+tcDoStmts ListComp stmts method_names res_ty
+ = unifyListTy res_ty `thenM` \ elt_ty ->
+ tcStmts ListComp (mkListTy, elt_ty) stmts `thenM` \ stmts' ->
+ returnM (EmptyMonoBinds, stmts', [{- unused -}])
+
+tcDoStmts do_or_mdo_expr stmts method_names res_ty
+ = newTyVarTy (mkArrowKind liftedTypeKind liftedTypeKind) `thenM` \ m_ty ->
+ newTyVarTy liftedTypeKind `thenM` \ elt_ty ->
+ unifyTauTy res_ty (mkAppTy m_ty elt_ty) `thenM_`
+
+ tcStmts do_or_mdo_expr (mkAppTy m_ty, elt_ty) stmts `thenM` \ stmts' ->
+
+ -- Build the then and zero methods in case we need them
+ -- It's important that "then" and "return" appear just once in the final LIE,
+ -- not only for typechecker efficiency, but also because otherwise during
+ -- simplification we end up with silly stuff like
+ -- then = case d of (t,r) -> t
+ -- then = then
+ -- where the second "then" sees that it already exists in the "available" stuff.
+ --
+ mapAndUnzipM (tc_syn_name m_ty)
+ (zipEqual "tcDoStmts" currentMonadNames method_names) `thenM` \ (binds, ids) ->
+ returnM (andMonoBindList binds, stmts', ids)
+ where
+ currentMonadNames = case do_or_mdo_expr of
+ DoExpr -> monadNames
+ MDoExpr -> monadNames ++ [mfixName]
+ tc_syn_name :: TcType -> (Name,Name) -> TcM (TcMonoBinds, Id)
+ tc_syn_name m_ty (std_nm, usr_nm)
+ = tcSyntaxName DoOrigin m_ty std_nm usr_nm `thenM` \ (expr, expr_ty) ->
+ case expr of
+ HsVar v -> returnM (EmptyMonoBinds, v)
+ other -> newUnique `thenM` \ uniq ->
+ let
+ id = mkSysLocal FSLIT("syn") uniq expr_ty
+ in
+ returnM (VarMonoBind id expr, id)
\end{code}
\begin{code}
tcStmts do_or_lc m_ty stmts
- = tcStmtsAndThen (:) do_or_lc m_ty stmts (returnTc ([], emptyLIE))
+ = ASSERT( notNull stmts )
+ tcStmtsAndThen (:) do_or_lc m_ty stmts (returnM [])
tcStmtsAndThen
:: (TcStmt -> thing -> thing) -- Combiner
- -> RenamedMatchContext
+ -> HsStmtContext Name
-> (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]
- -> TcM (thing, LIE)
- -> TcM (thing, LIE)
+ -> TcM thing
+ -> TcM thing
-- Base case
tcStmtsAndThen combine do_or_lc m_ty [] do_next
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)
-
+ = addSrcLoc src_loc $
+ addErrCtxt (stmtCtxt do_or_lc stmt) $
+ newTyVarTy liftedTypeKind `thenM` \ pat_ty ->
+ tcMonoExpr exp (m pat_ty) `thenM` \ exp' ->
+ tcMatchPats [pat] (mkFunTy pat_ty (m elt_ty)) (\ _ ->
+ popErrCtxt thing_inside
+ ) `thenM` \ ([pat'], thing, dict_binds) ->
+ returnM (combine (BindStmt pat' exp' src_loc)
+ (glue_binds combine dict_binds thing))
-- ParStmt
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)
+ = loop bndr_stmts_s `thenM` \ (pairs', thing) ->
+ returnM (combine (ParStmtOut pairs') thing)
where
loop []
- = thing_inside `thenTc` \ (thing, stmts_lie) ->
- returnTc (([], thing), stmts_lie)
+ = thing_inside `thenM` \ thing ->
+ returnM ([], thing)
loop ((bndrs,stmts) : pairs)
= tcStmtsAndThen
- combine_par (DoCtxt ListComp) m_ty stmts
+ combine_par 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) ->
+ (tcLookupLocalIds bndrs `thenM` \ bndrs' ->
+ loop pairs `thenM` \ (pairs', thing) ->
+ returnM ([], (bndrs', pairs', thing))) `thenM` \ (stmts', (bndrs', pairs', thing)) ->
- returnTc ( ((bndrs',stmts') : pairs', thing), lie)
+ returnM ((bndrs',stmts') : pairs', thing)
combine_par stmt (stmts, thing) = (stmt:stmts, thing)
+ -- RecStmt
+tcStmtAndThen combine do_or_lc m_ty (RecStmt recNames stmts _) thing_inside
+ = newTyVarTys (length recNames) liftedTypeKind `thenM` \ recTys ->
+ let
+ mono_ids = zipWith mkLocalId recNames recTys
+ in
+ tcExtendLocalValEnv mono_ids $
+ tcStmtsAndThen combine_rec do_or_lc m_ty stmts (
+ mappM tc_ret (recNames `zip` recTys) `thenM` \ rets ->
+ returnM ([], rets)
+ ) `thenM` \ (stmts', rets) ->
+
+ -- NB: it's the mono_ids that scope over this part
+ thing_inside `thenM` \ thing ->
+
+ returnM (combine (RecStmt mono_ids stmts' 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)
+ = tcLookupId rec_name `thenM` \ poly_id ->
+ -- poly_id may have a polymorphic type
+ -- but mono_ty is just a monomorphic type variable
+ tcSubExp mono_ty (idType poly_id) `thenM` \ co_fn ->
+ returnM (co_fn <$> HsVar poly_id)
+
-- ExprStmt
tcStmtAndThen combine do_or_lc m_ty@(m, res_elt_ty) stmt@(ExprStmt exp _ locn) thing_inside
- = tcSetErrCtxt (stmtCtxt do_or_lc stmt) (
+ = addErrCtxt (stmtCtxt do_or_lc stmt) (
if isDoExpr do_or_lc then
- newTyVarTy openTypeKind `thenNF_Tc` \ any_ty ->
- tcExpr exp (m any_ty) `thenNF_Tc` \ (exp', lie) ->
- returnTc (ExprStmt exp' any_ty locn, lie)
+ newTyVarTy openTypeKind `thenM` \ any_ty ->
+ tcMonoExpr exp (m any_ty) `thenM` \ exp' ->
+ returnM (ExprStmt exp' any_ty locn)
else
- tcExpr exp boolTy `thenNF_Tc` \ (exp', lie) ->
- returnTc (ExprStmt exp' boolTy locn, lie)
- ) `thenTc` \ (stmt', stmt_lie) ->
+ tcMonoExpr exp boolTy `thenM` \ exp' ->
+ returnM (ExprStmt exp' boolTy locn)
+ ) `thenM` \ stmt' ->
- thing_inside `thenTc` \ (thing, stmts_lie) ->
-
- returnTc (combine stmt' thing, stmt_lie `plusLIE` stmts_lie)
+ thing_inside `thenM` \ thing ->
+ returnM (combine stmt' thing)
-- 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) (
+ = addErrCtxt (resCtxt do_or_lc stmt) (
if isDoExpr do_or_lc then
- tcExpr exp (m res_elt_ty)
+ tcMonoExpr exp (m res_elt_ty)
else
- tcExpr exp res_elt_ty
- ) `thenTc` \ (exp', stmt_lie) ->
+ tcMonoExpr exp res_elt_ty
+ ) `thenM` \ exp' ->
- thing_inside `thenTc` \ (thing, stmts_lie) ->
+ thing_inside `thenM` \ thing ->
- returnTc (combine (ResultStmt exp' locn) thing,
- stmt_lie `plusLIE` stmts_lie)
+ returnM (combine (ResultStmt exp' locn) thing)
------------------------------
-glue_binds combine is_rec binds thing
- | nullMonoBinds binds = thing
- | otherwise = combine (LetStmt (mkMonoBind binds [] is_rec)) thing
+glue_binds combine EmptyBinds thing = thing
+glue_binds combine other_binds thing = combine (LetStmt other_binds) thing
\end{code}
\end{code}
\begin{code}
-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)]
+
+matchCtxt ctxt match = hang (ptext SLIT("In") <+> pprMatchContext ctxt <> colon) 4 (pprMatch ctxt match)
+stmtCtxt do_or_lc stmt = hang (ptext SLIT("In") <+> pprStmtContext do_or_lc <> colon) 4 (ppr stmt)
+resCtxt do_or_lc stmt = hang (ptext SLIT("In") <+> pprStmtResultContext do_or_lc <> colon) 4 (ppr stmt)
+
+sigPatCtxt bound_tvs bound_ids match_ty tidy_env
+ = zonkTcType match_ty `thenM` \ match_ty' ->
+ let
+ (env1, tidy_tys) = tidyOpenTypes tidy_env (map idType show_ids)
+ (env2, tidy_mty) = tidyOpenType env1 match_ty'
+ 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("and whose type is") <+> ppr tidy_mty])
+ 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