%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1994
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[TcMatches]{Typecheck some @Matches@}
\begin{code}
-#include "HsVersions.h"
-
-module TcMatches ( tcMatchesFun, tcMatchesCase, tcMatchExpected ) where
+module TcMatches ( tcMatchesFun, tcMatchesCase, tcMatchLambda,
+ tcStmts, tcStmtsAndThen, tcGRHSs
+ ) where
-IMP_Ubiq()
+#include "HsVersions.h"
-#if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ <= 201
-IMPORT_DELOOPER(TcLoop) ( tcGRHSsAndBinds )
-#else
-import {-# SOURCE #-} TcGRHSs ( tcGRHSsAndBinds )
-#endif
+import {-# SOURCE #-} TcExpr( tcExpr )
-import HsSyn ( Match(..), GRHSsAndBinds(..), GRHS(..), InPat,
- HsExpr(..), HsBinds(..), MonoBinds(..), OutPat, Fake, Stmt,
- Sig, HsLit, DoOrListComp, Fixity, HsType, ArithSeqInfo,
- collectPatBinders, pprMatch )
-import RnHsSyn ( SYN_IE(RenamedMatch) )
-import TcHsSyn ( SYN_IE(TcMatch) )
+import HsSyn ( HsBinds(..), Match(..), GRHSs(..), GRHS(..),
+ MonoBinds(..), Stmt(..), HsMatchContext(..), HsDoContext(..),
+ pprMatch, getMatchLoc, pprMatchContext, isDoExpr,
+ mkMonoBind, nullMonoBinds, collectSigTysFromPats
+ )
+import RnHsSyn ( RenamedMatch, RenamedGRHSs, RenamedStmt, RenamedPat, RenamedHsType,
+ RenamedMatchContext, extractHsTyVars )
+import TcHsSyn ( TcMatch, TcGRHSs, TcStmt, TcDictBinds, TypecheckedPat, TypecheckedMatchContext )
import TcMonad
-import Inst ( Inst, SYN_IE(LIE), plusLIE )
-import TcEnv ( newMonoIds )
-import TcPat ( tcPat )
-import TcType ( TcIdOcc(..), SYN_IE(TcType), TcMaybe, zonkTcType )
-import TcSimplify ( bindInstsOfLocalFuns )
-import Unify ( unifyTauTy, unifyTauTyList, unifyFunTy )
-import Name ( Name {- instance Outputable -} )
-
-import Kind ( Kind, mkTypeKind )
-import Pretty
-import Type ( isTyVarTy, isTauTy, mkFunTy, getFunTy_maybe )
-import Util
+import TcMonoType ( kcHsSigTypes, tcScopedTyVars, checkSigTyVars, tcHsSigType, sigPatCtxt )
+import Inst ( LIE, isEmptyLIE, plusLIE, emptyLIE, plusLIEs, lieToList )
+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 )
+import Id ( idType )
+import BasicTypes ( RecFlag(..) )
+import Type ( tyVarsOfType, isTauTy, mkFunTy,
+ liftedTypeKind, openTypeKind, splitSigmaTy )
+import NameSet
+import VarSet
+import Var ( Id )
+import Bag
import Outputable
-#if __GLASGOW_HASKELL__ >= 202
-import SrcLoc (SrcLoc)
-#endif
-
+import List ( nub )
\end{code}
+%************************************************************************
+%* *
+\subsection{tcMatchesFun, tcMatchesCase}
+%* *
+%************************************************************************
+
@tcMatchesFun@ typechecks a @[Match]@ list which occurs in a
@FunMonoBind@. The second argument is the name of the function, which
is used in error messages. It checks that all the equations have the
same number of arguments before using @tcMatches@ to do the work.
\begin{code}
-tcMatchesFun :: Name
- -> TcType s -- Expected type
+tcMatchesFun :: [(Name,Id)] -- Bindings for the variables bound in this group
+ -> Name
+ -> TcType -- Expected type
-> [RenamedMatch]
- -> TcM s ([TcMatch s], LIE s)
+ -> TcM ([TcMatch], LIE)
-tcMatchesFun fun_name expected_ty matches@(first_match:_)
- = -- Set the location to that of the first equation, so that
+tcMatchesFun xve fun_name expected_ty matches@(first_match:_)
+ = -- Check that they all have the same no of arguments
+ -- Set the location to that of the first equation, 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...
-
- tcAddSrcLoc (get_Match_loc first_match) (
-
- -- Check that they all have the same no of arguments
- checkTc (all_same (noOfArgs matches))
- (varyingArgsErr fun_name matches) `thenTc_`
+ tcAddSrcLoc (getMatchLoc first_match) (
+ checkTc (sameNoOfArgs matches)
+ (varyingArgsErr fun_name matches)
+ ) `thenTc_`
-- 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
- -- We need to substitute so that we can see as much about the type as possible
- zonkTcType expected_ty `thenNF_Tc` \ expected_ty' ->
- tcMatchesExpected expected_ty' (MFun fun_name) matches
-
- )
- where
- all_same :: [Int] -> Bool
- all_same [] = True -- Should never happen (ToDo: panic?)
- all_same [x] = True
- all_same (x:xs) = all ((==) x) xs
+ -- No need to zonk expected_ty, because unifyFunTy does that on the fly
+ tcMatches xve (FunRhs fun_name) matches expected_ty
\end{code}
@tcMatchesCase@ doesn't do the argument-count check because the
parser guarantees that each equation has exactly one argument.
\begin{code}
-tcMatchesCase :: TcType s -> [RenamedMatch] -> TcM s ([TcMatch s], LIE s)
-tcMatchesCase expected_ty matches = tcMatchesExpected expected_ty MCase matches
+tcMatchesCase :: [RenamedMatch] -- The case alternatives
+ -> TcType -- Type of whole case expressions
+ -> TcM (TcType, -- Inferred type of the scrutinee
+ [TcMatch], -- Translated alternatives
+ LIE)
+
+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)
+
+tcMatchLambda :: RenamedMatch -> TcType -> TcM (TcMatch, LIE)
+tcMatchLambda match res_ty = tcMatch [] LambdaExpr match res_ty
\end{code}
\begin{code}
-data FunOrCase = MCase | MFun Name -- Records whether doing fun or case rhss;
- -- used to produced better error messages
-
-tcMatchesExpected :: TcType s
- -> FunOrCase
- -> [RenamedMatch]
- -> TcM s ([TcMatch s], LIE s)
-
-tcMatchesExpected expected_ty fun_or_case [match]
- = tcAddSrcLoc (get_Match_loc match) $
- tcAddErrCtxt (matchCtxt fun_or_case match) $
- tcMatchExpected expected_ty match `thenTc` \ (match', lie) ->
- returnTc ([match'], lie)
-
-tcMatchesExpected expected_ty fun_or_case (match1 : matches)
- = tcAddSrcLoc (get_Match_loc match1) (
- tcAddErrCtxt (matchCtxt fun_or_case match1) $
- tcMatchExpected expected_ty match1
- ) `thenTc` \ (match1', lie1) ->
- tcMatchesExpected expected_ty fun_or_case matches `thenTc` \ (matches', lie2) ->
- returnTc (match1' : matches', plusLIE lie1 lie2)
+tcMatches :: [(Name,Id)]
+ -> 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)
+ where
+ tc_match match = tcMatch xve fun_or_case match expected_ty
\end{code}
+
+%************************************************************************
+%* *
+\subsection{tcMatch}
+%* *
+%************************************************************************
+
\begin{code}
-tcMatchExpected
- :: TcType s -- This gives the expected
- -- result-type of the Match. Early unification
- -- with this guy gives better error messages
+tcMatch :: [(Name,Id)]
+ -> RenamedMatchContext
-> RenamedMatch
- -> TcM s (TcMatch s,LIE s) -- NB No type returned, because it was passed
- -- in instead!
+ -> TcType -- Expected result-type of the Match.
+ -- Early unification with this guy gives better error messages
+ -> TcM (TcMatch, LIE)
+
+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)
+
+ 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_`
+
+ -- Deal with the result signature
+ tc_result_sig maybe_rhs_sig (
+
+ -- Typecheck the body
+ tcExtendLocalValEnv xve1 $
+ tcGRHSs ctxt grhss rhs_ty `thenTc` \ (grhss', lie) ->
+ returnTc ((pats', grhss'), lie)
+ )
+
+ tc_result_sig Nothing thing_inside
+ = thing_inside
+ tc_result_sig (Just sig) thing_inside
+ = tcAddScopedTyVars [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 expected_ty sig_ty `thenTc_`
+ thing_inside
+
+
+ -- 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 :: RenamedMatchContext -> RenamedGRHSs
+ -> TcType
+ -> TcM (TcGRHSs, LIE)
+
+tcGRHSs ctxt (GRHSs grhss binds _) expected_ty
+ = tcBindsAndThen glue_on binds (tc_grhss grhss)
+ where
+ tc_grhss grhss
+ = mapAndUnzipTc tc_grhs grhss `thenTc` \ (grhss', lies) ->
+ returnTc (GRHSs grhss' EmptyBinds (Just expected_ty), plusLIEs lies)
+
+ tc_grhs (GRHS guarded locn)
+ = tcAddSrcLoc locn $
+ tcStmts ctxt (\ty -> ty, expected_ty) guarded `thenTc` \ (guarded', lie) ->
+ returnTc (GRHS guarded' locn, lie)
+\end{code}
-tcMatchExpected expected_ty the_match@(PatMatch pat match)
- = unifyFunTy expected_ty `thenTc` \ (arg_ty, rest_ty) ->
- let binders = collectPatBinders pat
+%************************************************************************
+%* *
+\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
- newMonoIds binders mkTypeKind (\ mono_ids ->
- tcPat pat `thenTc` \ (pat', lie_pat, pat_ty) ->
- unifyTauTy pat_ty arg_ty `thenTc_`
- tcMatchExpected rest_ty match `thenTc` \ (match', lie_match) ->
- -- 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
- --
- -- 99% of the time there are no bindings. In the unusual case we
- -- march down the match to dump them in the right place (boring but easy).
- bindInstsOfLocalFuns lie_match mono_ids `thenTc` \ (lie_match', inst_mbinds) ->
- let
- inst_binds = MonoBind inst_mbinds [] False
- match'' = case inst_mbinds of
- EmptyMonoBinds -> match'
- other -> glue_on match'
- glue_on (PatMatch p m) = PatMatch p (glue_on m)
- glue_on (GRHSMatch (GRHSsAndBindsOut grhss binds ty))
- = (GRHSMatch (GRHSsAndBindsOut grhss
- (inst_binds `ThenBinds` binds)
- ty))
- glue_on (SimpleMatch expr) = SimpleMatch (HsLet inst_binds expr)
- in
- returnTc (PatMatch pat' match'',
- plusLIE lie_pat lie_match')
- )
+ 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
+ -> LIE -- Required context
+ -> TcType -- and result type; vars in here must not escape
+ -> TcM (LIE, TcDictBinds) -- LIE to float out and dict bindings
+tcCheckExistentialPat ids ex_tvs lie_avail lie_req result_ty
+ | isEmptyBag ex_tvs && all not_overloaded 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)
+
+ | otherwise
+ = tcExtendGlobalTyVars (tyVarsOfType result_ty) $
+ tcAddErrCtxtM (sigPatCtxt tv_list ids) $
+
+ -- 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) ->
+
+ -- 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_`
+
+ returnTc (lie2, dict_binds `AndMonoBinds` inst_binds)
+ where
+ doc = text ("the existential context of a data constructor")
+ tv_list = bagToList ex_tvs
+ not_overloaded id = case splitSigmaTy (idType id) of
+ (_, theta, _) -> null theta
-tcMatchExpected expected_ty (GRHSMatch grhss_and_binds)
- = tcGRHSsAndBinds expected_ty grhss_and_binds `thenTc` \ (grhss_and_binds', lie) ->
- checkTc (isTauTy expected_ty)
- lurkingRank2SigErr `thenTc_`
- returnTc (GRHSMatch grhss_and_binds', lie)
+tc_match_pats [] expected_ty
+ = returnTc (expected_ty, [], emptyLIE, emptyBag, emptyBag, emptyLIE)
+
+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) ->
+ 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
+ )
\end{code}
-@noOfArgs@ takes a @[RenamedMatch]@ and returns a list telling how
-many arguments were used in each of the equations. This is used to
-report a sensible error message when different equations have
-different numbers of arguments.
+%************************************************************************
+%* *
+\subsection{tcStmts}
+%* *
+%************************************************************************
-\begin{code}
-noOfArgs :: [RenamedMatch] -> [Int]
+Typechecking statements is rendered a bit tricky by parallel list comprehensions:
-noOfArgs ms = map args_in_match ms
- where
- args_in_match :: RenamedMatch -> Int
- args_in_match (GRHSMatch _) = 0
- args_in_match (PatMatch _ match) = 1 + args_in_match match
-\end{code}
+ [ (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).
+Similarly if we had an existential pattern match:
+
+ data T = forall a. Show a => C a
+
+ [ (show x, show y) | ... ; C x <- ...
+ | ... ; C y <- ... ]
-@get_Match_loc@ takes a @RenamedMatch@ and returns the
-source-location gotten from the GRHS inside.
-THis is something of a nuisance, but no more.
+Then we need the LIE from (show x, show y) to be simplified against
+the bindings for x and y.
+
+It's difficult to do this in parallel, so we rely on the renamer to
+ensure that g,h and x,y don't duplicate, and simply grow the environment.
+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.
\begin{code}
-get_Match_loc :: RenamedMatch -> SrcLoc
-
-get_Match_loc (PatMatch _ m) = get_Match_loc m
-get_Match_loc (GRHSMatch (GRHSsAndBindsIn (g:_) _))
- = get_GRHS_loc g
- where
- get_GRHS_loc (OtherwiseGRHS _ locn) = locn
- get_GRHS_loc (GRHS _ _ locn) = locn
+tcStmts do_or_lc m_ty stmts
+ = tcStmtsAndThen (:) do_or_lc m_ty stmts (returnTc ([], emptyLIE))
+
+tcStmtsAndThen
+ :: (TcStmt -> thing -> thing) -- Combiner
+ -> 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]
+ -> TcM (thing, LIE)
+ -> TcM (thing, LIE)
+
+ -- Base case
+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
+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
+ 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
+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 []
+ = thing_inside `thenTc` \ (thing, stmts_lie) ->
+ returnTc (([], thing), stmts_lie)
+
+ loop ((bndrs,stmts) : pairs)
+ = tcStmtsAndThen
+ 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)
+
+ -- ExprStmt
+tcStmtAndThen combine do_or_lc m_ty@(m, res_elt_ty) stmt@(ExprStmt exp locn) thing_inside
+ = tcSetErrCtxt (stmtCtxt do_or_lc stmt) (
+ 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) ->
+
+ thing_inside `thenTc` \ (thing, stmts_lie) ->
+
+ returnTc (combine (ExprStmt exp' locn) thing,
+ stmt_lie `plusLIE` stmts_lie)
+
+
+ -- 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
+ | nullMonoBinds binds = thing
+ | otherwise = combine (LetStmt (mkMonoBind binds [] is_rec)) thing
\end{code}
-Errors and contexts
-~~~~~~~~~~~~~~~~~~~
-\begin{code}
-matchCtxt MCase match sty
- = hang (ptext SLIT("In a \"case\" branch:"))
- 4 (pprMatch sty True{-is_case-} match)
-matchCtxt (MFun fun) match sty
- = hang (hcat [ptext SLIT("In an equation for function "), ppr sty fun, char ':'])
- 4 (pprQuote sty $ \sty -> hcat [ppr sty fun, space, pprMatch sty False{-not case-} match])
-\end{code}
+%************************************************************************
+%* *
+\subsection{Errors and contexts}
+%* *
+%************************************************************************
+
+@sameNoOfArgs@ takes a @[RenamedMatch]@ and decides whether the same
+number of args are used in each equation.
+\begin{code}
+sameNoOfArgs :: [RenamedMatch] -> Bool
+sameNoOfArgs matches = length (nub (map args_in_match matches)) == 1
+ where
+ args_in_match :: RenamedMatch -> Int
+ args_in_match (Match _ pats _ _) = length pats
+\end{code}
\begin{code}
-varyingArgsErr name matches sty
- = sep [ptext SLIT("Varying number of arguments for function"), ppr sty name]
+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 sty
+lurkingRank2SigErr
= ptext SLIT("Too few explicit arguments when defining a function with a rank-2 type")
\end{code}
projects / ghc-hetmet.git / blobdiff