%
-% (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}
+module TcMatches ( tcMatchesFun, tcMatchesCase, tcMatchLambda,
+ tcStmts, tcStmtsAndThen, tcGRHSs
+ ) where
+
#include "HsVersions.h"
-module TcMatches ( tcMatchesFun, tcMatchesCase, tcMatch ) where
-
-import TcMonad -- typechecking monad machinery
-import TcMonadFns ( mkIdsWithOpenTyVarTys )
-import AbsSyn -- the stuff being typechecked
-
-import AbsPrel ( mkFunTy )
-import AbsUniType ( isTyVarTy, maybeUnpackFunTy )
-import E ( E, growE_LVE, LVE(..), GVE(..) )
-#if USE_ATTACK_PRAGMAS
-import CE
-import TCE
-#endif
-import Errors ( varyingArgsErr, Error(..), UnifyErrContext(..) )
-import LIE ( LIE, plusLIE )
-import Maybes ( Maybe(..) )
-import TcGRHSs ( tcGRHSsAndBinds )
-import TcPat ( tcPat )
-import Unify ( unifyTauTy, unifyTauTyList )
-import Util
+import {-# SOURCE #-} TcExpr( tcExpr )
+
+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 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
+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 :: E -> Name
- -> UniType -- Expected type
+tcMatchesFun :: [(Name,Id)] -- Bindings for the variables bound in this group
+ -> Name
+ -> TcType -- Expected type
-> [RenamedMatch]
- -> TcM ([TypecheckedMatch], LIE)
+ -> TcM ([TcMatch], LIE)
-tcMatchesFun e 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...
-
- addSrcLocTc (get_Match_loc first_match) (
-
- -- Check that they all have the same no of arguments
- checkTc (not (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
- applyTcSubstToTy expected_ty `thenNF_Tc` \ expected_ty' ->
- tcMatchesExpected e expected_ty' (\ m -> FunMonoBindsCtxt fun_name [m]) 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 :: E -> [RenamedMatch]
- -> TcM ([TypecheckedMatch], LIE, UniType)
-
-tcMatchesCase e matches
- =
-
- -- Typecheck them
- tcMatches e matches `thenTc` \ (matches', lie, tys@(first_ty:_)) ->
+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}
- -- Set the location to that of the first equation, so that
- -- any inter-equation error messages get some vaguely sensible location
- addSrcLocTc (get_Match_loc (head matches)) (
- unifyTauTyList tys (CaseBranchesCtxt matches)
- ) `thenTc_`
- returnTc (matches', lie, first_ty)
+\begin{code}
+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}
-tcMatchesExpected :: E
- -> UniType
- -> (RenamedMatch -> UnifyErrContext)
- -> [RenamedMatch]
- -> TcM ([TypecheckedMatch], LIE)
-
-tcMatchesExpected e expected_ty err_ctxt_fn [match]
- = addSrcLocTc (get_Match_loc match) (
- tcMatchExpected e expected_ty (err_ctxt_fn match) match
- ) `thenTc` \ (match', lie) ->
- returnTc ([match'], lie)
-
-tcMatchesExpected e expected_ty err_ctxt_fn ms@(match1 : matches)
- = addSrcLocTc (get_Match_loc match1) (
- tcMatchExpected e expected_ty (err_ctxt_fn match1) match1
- ) `thenTc` \ (match1', lie1) ->
- tcMatchesExpected e expected_ty err_ctxt_fn matches `thenTc` \ (matches', lie2) ->
- returnTc (match1' : matches', plusLIE lie1 lie2)
-
-tcMatches :: E -> [RenamedMatch] -> TcM ([TypecheckedMatch], LIE, [UniType])
-
-tcMatches e [match]
- = tcMatch e match `thenTc` \ (match', lie, ty) ->
- returnTc ([match'], lie, [ty])
-
-tcMatches e ms@(match1 : matches)
- = addSrcLocTc (get_Match_loc match1) (
- tcMatch e match1
- ) `thenTc` \ (match1', lie1, match1_ty) ->
- tcMatches e matches `thenTc` \ (matches', lie2, matches_ty) ->
- returnTc (match1' : matches', plusLIE lie1 lie2, match1_ty : matches_ty)
+tcMatch :: [(Name,Id)]
+ -> RenamedMatchContext
+ -> RenamedMatch
+ -> 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}
-\begin{code}
-tcMatchExpected
- :: E
- -> UniType -- This gives the expected
- -- result-type of the Match. Early unification
- -- with this guy gives better error messages
- -> UnifyErrContext
- -> RenamedMatch
- -> TcM (TypecheckedMatch,LIE)
- -- NB No type returned, because it was passed
- -- in instead!
-
-tcMatchExpected e expected_ty err_ctxt the_match@(PatMatch pat match)
- = case maybeUnpackFunTy expected_ty of
-
- Nothing -> -- Not a function type (eg type variable)
- -- So use tcMatch instead
- tcMatch e the_match `thenTc` \ (match', lie_match, match_ty) ->
- unifyTauTy match_ty expected_ty err_ctxt `thenTc_`
- returnTc (match', lie_match)
-
- Just (arg_ty,rest_ty) -> -- It's a function type!
- let binders = collectPatBinders pat
- in
- mkIdsWithOpenTyVarTys binders `thenNF_Tc` \ lve ->
- let e' = growE_LVE e lve
- in
- tcPat e' pat `thenTc` \ (pat', lie_pat, pat_ty) ->
-
- unifyTauTy arg_ty pat_ty err_ctxt `thenTc_`
- tcMatchExpected e' rest_ty err_ctxt match `thenTc` \ (match', lie_match) ->
- returnTc (PatMatch pat' match',
- plusLIE lie_pat lie_match)
-
-tcMatchExpected e expected_ty err_ctxt (GRHSMatch grhss_and_binds)
- = tcGRHSsAndBinds e grhss_and_binds `thenTc` \ (grhss_and_binds', lie, grhss_ty) ->
- unifyTauTy grhss_ty expected_ty err_ctxt `thenTc_`
- returnTc (GRHSMatch grhss_and_binds', lie)
-
-tcMatch :: E
- -> RenamedMatch
- -> TcM (TypecheckedMatch,LIE,UniType)
-
-tcMatch e (PatMatch pat match)
- = let binders = collectPatBinders pat
- in
- mkIdsWithOpenTyVarTys binders `thenNF_Tc` \ lve ->
- let e' = growE_LVE e lve
+
+%************************************************************************
+%* *
+\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
- tcPat e' pat `thenTc` \ (pat', lie_pat, pat_ty) ->
- tcMatch e' match `thenTc` \ (match', lie_match, match_ty) ->
+ 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
+
+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}
--- We don't do this any more, do we?
--- applyTcSubstToTy pat_ty `thenNF_Tc`\ pat_ty' ->
- returnTc (PatMatch pat' match',
- plusLIE lie_pat lie_match,
- mkFunTy pat_ty match_ty)
+%************************************************************************
+%* *
+\subsection{tcStmts}
+%* *
+%************************************************************************
-tcMatch e (GRHSMatch grhss_and_binds)
- = tcGRHSsAndBinds e grhss_and_binds `thenTc` \ (grhss_and_binds', lie, grhss_ty) ->
- returnTc (GRHSMatch grhss_and_binds', lie, grhss_ty)
-\end{code}
+Typechecking statements is rendered a bit tricky by parallel list comprehensions:
+
+ [ (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 <- ... ]
+Then we need the LIE from (show x, show y) to be simplified against
+the bindings for x and y.
-@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.
+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}
-noOfArgs :: [RenamedMatch] -> [Int]
+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}
+
+
+%************************************************************************
+%* *
+\subsection{Errors and contexts}
+%* *
+%************************************************************************
+
+@sameNoOfArgs@ takes a @[RenamedMatch]@ and decides whether the same
+number of args are used in each equation.
-noOfArgs ms = map args_in_match ms
+\begin{code}
+sameNoOfArgs :: [RenamedMatch] -> Bool
+sameNoOfArgs matches = length (nub (map args_in_match matches)) == 1
where
args_in_match :: RenamedMatch -> Int
- args_in_match (GRHSMatch _) = 0
- args_in_match (PatMatch _ match) = 1 + args_in_match match
+ args_in_match (Match _ pats _ _) = length pats
\end{code}
-@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.
-
\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
+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")
\end{code}