X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FdeSugar%2FMatch.lhs;h=bbc37b33b8012cdea7f06cc32e463c95f68e1569;hb=5d3051c66796dcf884b052f9e4afc3ed19b9f514;hp=f65de3c3f2d4624791d728ac7eb4ccbc731983fc;hpb=9bb6b6d0fbca6c82040027fab9859c9fcbc1ef7e;p=ghc-hetmet.git diff --git a/ghc/compiler/deSugar/Match.lhs b/ghc/compiler/deSugar/Match.lhs index f65de3c..bbc37b3 100644 --- a/ghc/compiler/deSugar/Match.lhs +++ b/ghc/compiler/deSugar/Match.lhs @@ -4,30 +4,34 @@ \section[Main_match]{The @match@ function} \begin{code} -module Match ( match, matchExport, matchWrapper, matchSimply, matchSinglePat ) where +module Match ( match, matchWrapper, matchSimply, matchSinglePat ) where #include "HsVersions.h" -import CmdLineOpts ( DynFlag(..), DynFlags, dopt ) +import DynFlags ( DynFlag(..), dopt ) import HsSyn -import TcHsSyn ( TypecheckedPat, TypecheckedMatch ) -import DsHsSyn ( outPatType ) +import TcHsSyn ( mkVanillaTuplePat ) import Check ( check, ExhaustivePat ) import CoreSyn -import CoreUtils ( bindNonRec ) +import CoreUtils ( bindNonRec, exprType ) import DsMonad +import DsBinds ( dsLHsBinds ) import DsGRHSs ( dsGRHSs ) import DsUtils -import Id ( idType, recordSelectorFieldLabel, Id ) -import DataCon ( dataConFieldLabels, dataConInstOrigArgTys ) +import Id ( idName, idType, Id ) +import DataCon ( dataConFieldLabels, dataConInstOrigArgTys, isVanillaDataCon ) import MatchCon ( matchConFamily ) -import MatchLit ( matchLiterals ) +import MatchLit ( matchLiterals, matchNPlusKPats, matchNPats, tidyLitPat, tidyNPat ) import PrelInfo ( pAT_ERROR_ID ) -import Type ( splitAlgTyConApp, mkTyVarTys, Type ) -import TysWiredIn ( nilDataCon, consDataCon, mkTupleTy, mkListTy, tupleCon ) +import TcType ( Type, tcTyConAppArgs ) +import Type ( splitFunTysN, mkTyVarTys ) +import TysWiredIn ( consDataCon, mkListTy, unitTy, + tupleCon, parrFakeCon, mkPArrTy ) import BasicTypes ( Boxity(..) ) -import UniqSet -import ErrUtils ( addErrLocHdrLine, dontAddErrLoc ) +import ListSetOps ( runs ) +import SrcLoc ( noLoc, unLoc, Located(..) ) +import Util ( lengthExceeds, notNull ) +import Name ( Name ) import Outputable \end{code} @@ -39,36 +43,38 @@ It can not be called matchWrapper because this name already exists :-( JJCQ 30-Nov-1997 \begin{code} -matchExport :: [Id] -- Vars rep'ing the exprs we're matching with +matchCheck :: DsMatchContext + -> [Id] -- Vars rep'ing the exprs we're matching with + -> Type -- Type of the case expression -> [EquationInfo] -- Info about patterns, etc. (type synonym below) -> DsM MatchResult -- Desugared result! - -matchExport vars qs +matchCheck ctx vars ty qs = getDOptsDs `thenDs` \ dflags -> - matchExport_really dflags vars qs + matchCheck_really dflags ctx vars ty qs -matchExport_really dflags vars qs@((EqnInfo _ ctx _ (MatchResult _ _)) : _) +matchCheck_really dflags ctx vars ty qs | incomplete && shadow = dsShadowWarn ctx eqns_shadow `thenDs` \ () -> dsIncompleteWarn ctx pats `thenDs` \ () -> - match vars qs + match vars ty qs | incomplete = dsIncompleteWarn ctx pats `thenDs` \ () -> - match vars qs + match vars ty qs | shadow = dsShadowWarn ctx eqns_shadow `thenDs` \ () -> - match vars qs + match vars ty qs | otherwise = - match vars qs - where (pats,indexs) = check qs - incomplete = dopt Opt_WarnIncompletePatterns dflags - && (length pats /= 0) + match vars ty qs + where (pats, eqns_shadow) = check qs + incomplete = want_incomplete && (notNull pats) + want_incomplete = case ctx of + DsMatchContext RecUpd _ _ -> + dopt Opt_WarnIncompletePatternsRecUpd dflags + _ -> + dopt Opt_WarnIncompletePatterns dflags shadow = dopt Opt_WarnOverlappingPatterns dflags - && sizeUniqSet indexs < no_eqns - no_eqns = length qs - unused_eqns = uniqSetToList (mkUniqSet [1..no_eqns] `minusUniqSet` indexs) - eqns_shadow = map (\n -> qs!!(n - 1)) unused_eqns + && not (null eqns_shadow) \end{code} This variable shows the maximum number of lines of output generated for warnings. @@ -84,19 +90,21 @@ The next two functions create the warning message. \begin{code} dsShadowWarn :: DsMatchContext -> [EquationInfo] -> DsM () -dsShadowWarn ctx@(DsMatchContext kind _ _) qs = dsWarn warn - where - warn | length qs > maximum_output - = pp_context ctx (ptext SLIT("are overlapped")) - (\ f -> vcat (map (ppr_eqn f kind) (take maximum_output qs)) $$ - ptext SLIT("...")) - | otherwise - = pp_context ctx (ptext SLIT("are overlapped")) - (\ f -> vcat $ map (ppr_eqn f kind) qs) +dsShadowWarn ctx@(DsMatchContext kind _ loc) qs + = putSrcSpanDs loc (dsWarn warn) + where + warn | qs `lengthExceeds` maximum_output + = pp_context ctx (ptext SLIT("are overlapped")) + (\ f -> vcat (map (ppr_eqn f kind) (take maximum_output qs)) $$ + ptext SLIT("...")) + | otherwise + = pp_context ctx (ptext SLIT("are overlapped")) + (\ f -> vcat $ map (ppr_eqn f kind) qs) dsIncompleteWarn :: DsMatchContext -> [ExhaustivePat] -> DsM () -dsIncompleteWarn ctx@(DsMatchContext kind _ _) pats = dsWarn warn +dsIncompleteWarn ctx@(DsMatchContext kind _ loc) pats + = putSrcSpanDs loc (dsWarn warn) where warn = pp_context ctx (ptext SLIT("are non-exhaustive")) (\f -> hang (ptext SLIT("Patterns not matched:")) @@ -104,80 +112,22 @@ dsIncompleteWarn ctx@(DsMatchContext kind _ _) pats = dsWarn warn (take maximum_output pats)) $$ dots)) - dots | length pats > maximum_output = ptext SLIT("...") - | otherwise = empty + dots | pats `lengthExceeds` maximum_output = ptext SLIT("...") + | otherwise = empty -pp_context NoMatchContext msg rest_of_msg_fun - = dontAddErrLoc "" (ptext SLIT("Some match(es)") <+> hang msg 8 (rest_of_msg_fun id)) - -pp_context (DsMatchContext kind pats loc) msg rest_of_msg_fun - = case pp_match kind pats of - (ppr_match, pref) -> - addErrLocHdrLine loc message (nest 8 (rest_of_msg_fun pref)) - where - message = ptext SLIT("Pattern match(es)") <+> msg <+> ppr_match <> char ':' - where - pp_match (FunMatch fun) pats - = let ppr_fun = ppr fun in - ( hsep [ptext SLIT("in the definition of function"), quotes ppr_fun] - , (\ x -> ppr_fun <+> x) - ) - - pp_match CaseMatch pats - = (hang (ptext SLIT("in a group of case alternatives beginning")) - 4 (ppr_pats pats) - , id - ) - - pp_match RecUpdMatch pats - = (hang (ptext SLIT("in a record-update construct")) - 4 (ppr_pats pats) - , id - ) - - pp_match PatBindMatch pats - = ( hang (ptext SLIT("in a pattern binding")) - 4 (ppr_pats pats) - , id - ) - - pp_match LambdaMatch pats - = ( hang (ptext SLIT("in a lambda abstraction")) - 4 (ppr_pats pats) - , id - ) - - pp_match DoBindMatch pats - = ( hang (ptext SLIT("in a `do' pattern binding")) - 4 (ppr_pats pats) - , id - ) - - pp_match ListCompMatch pats - = ( hang (ptext SLIT("in a `list comprension' pattern binding")) - 4 (ppr_pats pats) - , id - ) - - pp_match LetMatch pats - = ( hang (ptext SLIT("in a `let' pattern binding")) - 4 (ppr_pats pats) - , id - ) +pp_context (DsMatchContext kind pats _loc) msg rest_of_msg_fun + = vcat [ptext SLIT("Pattern match(es)") <+> msg, + sep [ptext SLIT("In") <+> ppr_match <> char ':', nest 4 (rest_of_msg_fun pref)]] + where + (ppr_match, pref) + = case kind of + FunRhs fun -> (pprMatchContext kind, \ pp -> ppr fun <+> pp) + other -> (pprMatchContext kind, \ pp -> pp) ppr_pats pats = sep (map ppr pats) -separator (FunMatch _) = SLIT("=") -separator (CaseMatch) = SLIT("->") -separator (LambdaMatch) = SLIT("->") -separator (PatBindMatch) = panic "When is this used?" -separator (RecUpdMatch) = panic "When is this used?" -separator (DoBindMatch) = SLIT("<-") -separator (ListCompMatch) = SLIT("<-") -separator (LetMatch) = SLIT("=") - ppr_shadow_pats kind pats - = sep [ppr_pats pats, ptext (separator kind), ptext SLIT("...")] + = sep [ppr_pats pats, matchSeparator kind, ptext SLIT("...")] ppr_incomplete_pats kind (pats,[]) = ppr_pats pats ppr_incomplete_pats kind (pats,constraints) = @@ -187,7 +137,7 @@ ppr_incomplete_pats kind (pats,constraints) = ppr_constraint (var,pats) = sep [ppr var, ptext SLIT("`notElem`"), ppr pats] -ppr_eqn prefixF kind (EqnInfo _ _ pats _) = prefixF (ppr_shadow_pats kind pats) +ppr_eqn prefixF kind eqn = prefixF (ppr_shadow_pats kind (eqn_pats eqn)) \end{code} @@ -244,6 +194,7 @@ chance of working in our post-upheaval world of @Locals@.) So, the full type signature: \begin{code} match :: [Id] -- Variables rep'ing the exprs we're matching with + -> Type -- Type of the case expression -> [EquationInfo] -- Info about patterns, etc. (type synonym below) -> DsM MatchResult -- Desugared result! \end{code} @@ -274,7 +225,7 @@ Now {\em unmix} the equations into {\em blocks} [w/ local function patterns in column~1, or they all have constructor patterns in ... (see ``the mixture rule'' in SLPJ). \item -Call @matchUnmixedEqns@ on each block of equations; it will do the +Call @matchEqnBlock@ on each block of equations; it will do the appropriate thing for each kind of column-1 pattern, usually ending up in a recursive call to @match@. \end{enumerate} @@ -291,22 +242,16 @@ than the Wadler-chapter code for @match@ (p.~93, first @match@ clause). And gluing the ``success expressions'' together isn't quite so pretty. \begin{code} -match [] eqns_info - = complete_matches eqns_info +match [] ty eqns_info + = ASSERT( not (null eqns_info) ) + returnDs (foldr1 combineMatchResults match_results) where - complete_matches [eqn] - = complete_match eqn - - complete_matches (eqn:eqns) - = complete_match eqn `thenDs` \ match_result1 -> - complete_matches eqns `thenDs` \ match_result2 -> - returnDs (combineMatchResults match_result1 match_result2) - - complete_match (EqnInfo _ _ pats match_result) - = ASSERT( null pats ) - returnDs match_result + match_results = [ ASSERT( null (eqn_pats eqn) ) + adjustMatchResult (eqn_wrap eqn) (eqn_rhs eqn) + | eqn <- eqns_info ] \end{code} + %************************************************************************ %* * %* match: non-empty rule * @@ -326,42 +271,39 @@ Wadler-chapter @match@ (p.~93, last clause), and @match_unmixed_blk@ corresponds roughly to @matchVarCon@. \begin{code} -match vars@(v:vs) eqns_info - = mapDs (tidyEqnInfo v) eqns_info `thenDs` \ tidy_eqns_info -> - let - tidy_eqns_blks = unmix_eqns tidy_eqns_info - in - match_unmixed_eqn_blks vars tidy_eqns_blks +match vars@(v:_) ty eqns_info + = do { tidy_eqns <- mappM (tidyEqnInfo v) eqns_info + ; let eqns_blks = runs same_family tidy_eqns + ; match_results <- mappM match_block eqns_blks + ; ASSERT( not (null match_results) ) + return (foldr1 combineMatchResults match_results) } where - unmix_eqns [] = [] - unmix_eqns [eqn] = [ [eqn] ] - unmix_eqns (eq1@(EqnInfo _ _ (p1:p1s) _) : eq2@(EqnInfo _ _ (p2:p2s) _) : eqs) - = if ( (isWildPat p1 && isWildPat p2) - || (isConPat p1 && isConPat p2) - || (isLitPat p1 && isLitPat p2) ) then - eq1 `tack_onto` unmixed_rest - else - [ eq1 ] : unmixed_rest - where - unmixed_rest = unmix_eqns (eq2:eqs) - - x `tack_onto` xss = ( x : head xss) : tail xss - - ----------------------------------------------------------------------- - -- loop through the blocks: - -- subsequent blocks create a "fail expr" for the first one... - match_unmixed_eqn_blks :: [Id] - -> [ [EquationInfo] ] -- List of eqn BLOCKS - -> DsM MatchResult - - match_unmixed_eqn_blks vars [] = panic "match_unmixed_eqn_blks" - - match_unmixed_eqn_blks vars [eqn_blk] = matchUnmixedEqns vars eqn_blk - - match_unmixed_eqn_blks vars (eqn_blk:eqn_blks) - = matchUnmixedEqns vars eqn_blk `thenDs` \ match_result1 -> -- try to match with first blk - match_unmixed_eqn_blks vars eqn_blks `thenDs` \ match_result2 -> - returnDs (combineMatchResults match_result1 match_result2) + same_family eqn1 eqn2 + = samePatFamily (firstPat eqn1) (firstPat eqn2) + + match_block eqns + = case firstPat (head eqns) of + WildPat {} -> matchVariables vars ty eqns + ConPatOut {} -> matchConFamily vars ty eqns + NPlusKPat {} -> matchNPlusKPats vars ty eqns + NPat {} -> matchNPats vars ty eqns + LitPat {} -> matchLiterals vars ty eqns + +-- After tidying, there are only five kinds of patterns +samePatFamily (WildPat {}) (WildPat {}) = True +samePatFamily (ConPatOut {}) (ConPatOut {}) = True +samePatFamily (NPlusKPat {}) (NPlusKPat {}) = True +samePatFamily (NPat {}) (NPat {}) = True +samePatFamily (LitPat {}) (LitPat {}) = True +samePatFamily _ _ = False + +matchVariables :: [Id] -> Type -> [EquationInfo] -> DsM MatchResult +-- Real true variables, just like in matchVar, SLPJ p 94 +-- No binding to do: they'll all be wildcards by now (done in tidy) +matchVariables (var:vars) ty eqns = match vars ty (shiftEqns eqns) +\end{code} + + \end{code} Tidy up the leftmost pattern in an @EquationInfo@, given the variable @v@ @@ -375,7 +317,8 @@ Replace the `as' pattern @x@@p@ with the pattern p and a binding @x = v@. \item Removing lazy (irrefutable) patterns (you don't want to know...). \item -Converting explicit tuple- and list-pats into ordinary @ConPats@. +Converting explicit tuple-, list-, and parallel-array-pats into ordinary +@ConPats@. \item Convert the literal pat "" to []. \end{itemize} @@ -394,13 +337,14 @@ The @VarPat@ information isn't needed any more after this. Float, Double, at least) are converted to unboxed form; e.g., \tr{(NPat (HsInt i) _ _)} is converted to: \begin{verbatim} -(ConPat I# _ _ [LitPat (HsIntPrim i) _]) +(ConPat I# _ _ [LitPat (HsIntPrim i)]) \end{verbatim} \end{description} \begin{code} tidyEqnInfo :: Id -> EquationInfo -> DsM EquationInfo - -- DsM'd because of internal call to "match". + -- DsM'd because of internal call to dsLHsBinds + -- and mkSelectorBinds. -- "tidy1" does the interesting stuff, looking at -- one pattern and fiddling the list of bindings. -- @@ -412,32 +356,62 @@ tidyEqnInfo :: Id -> EquationInfo -> DsM EquationInfo -- NPlusKPat -- but no other -tidyEqnInfo v (EqnInfo n ctx (pat : pats) match_result) - = tidy1 v pat match_result `thenDs` \ (pat', match_result') -> - returnDs (EqnInfo n ctx (pat' : pats) match_result') - -tidy1 :: Id -- The Id being scrutinised - -> TypecheckedPat -- The pattern against which it is to be matched - -> MatchResult -- Current thing do do after matching - -> DsM (TypecheckedPat, -- Equivalent pattern - MatchResult) -- Augmented thing to do afterwards - -- The augmentation usually takes the form - -- of new bindings to be added to the front - -tidy1 v (VarPat var) match_result - = returnDs (WildPat (idType var), match_result') - where - match_result' | v == var = match_result - | otherwise = adjustMatchResult (bindNonRec var (Var v)) match_result - -tidy1 v (AsPat var pat) match_result - = tidy1 v pat match_result' - where - match_result' | v == var = match_result - | otherwise = adjustMatchResult (bindNonRec var (Var v)) match_result - -tidy1 v (WildPat ty) match_result - = returnDs (WildPat ty, match_result) +tidyEqnInfo v eqn@(EqnInfo { eqn_wrap = wrap, eqn_pats = pat : pats }) + = tidy1 v wrap pat `thenDs` \ (wrap', pat') -> + returnDs (eqn { eqn_wrap = wrap', eqn_pats = pat' : pats }) + +tidy1 :: Id -- The Id being scrutinised + -> DsWrapper -- Previous wrapping bindings + -> Pat Id -- The pattern against which it is to be matched + -> DsM (DsWrapper, -- Extra bindings around what to do afterwards + Pat Id) -- Equivalent pattern + +-- The extra bindings etc are all wrapped around the RHS of the match +-- so they are only available when matching is complete. But that's ok +-- becuase, for example, in the pattern x@(...), the x can only be +-- used in the RHS, not in the nested pattern, nor subsquent patterns +-- +-- However this does have an awkward consequence. The bindings in +-- a VarPatOut get wrapped around the result in right to left order, +-- rather than left to right. This only matters if one set of +-- bindings can mention things used in another, and that can happen +-- if we allow equality dictionary bindings of form d1=d2. +-- bindIInstsOfLocalFuns is now careful not to do this, but it's a wart. +-- (Without this care in bindInstsOfLocalFuns, compiling +-- Data.Generics.Schemes.hs fails in function everywhereBut.) + +------------------------------------------------------- +-- (pat', mr') = tidy1 v pat mr +-- tidies the *outer level only* of pat, giving pat' +-- It eliminates many pattern forms (as-patterns, variable patterns, +-- list patterns, etc) yielding one of: +-- WildPat +-- ConPatOut +-- LitPat +-- NPat +-- NPlusKPat + +tidy1 v wrap (ParPat pat) = tidy1 v wrap (unLoc pat) +tidy1 v wrap (SigPatOut pat _) = tidy1 v wrap (unLoc pat) +tidy1 v wrap (WildPat ty) = returnDs (wrap, WildPat ty) + + -- case v of { x -> mr[] } + -- = case v of { _ -> let x=v in mr[] } +tidy1 v wrap (VarPat var) + = returnDs (wrap . wrapBind var v, WildPat (idType var)) + +tidy1 v wrap (VarPatOut var binds) + = do { prs <- dsLHsBinds binds + ; return (wrap . wrapBind var v . mkDsLet (Rec prs), + WildPat (idType var)) } + + -- case v of { x@p -> mr[] } + -- = case v of { p -> let x=v in mr[] } +tidy1 v wrap (AsPat (L _ var) pat) + = tidy1 v (wrap . wrapBind var v) (unLoc pat) + +tidy1 v wrap (BangPat pat) + = tidy1 v (wrap . seqVar v) (unLoc pat) {- now, here we handle lazy patterns: tidy1 v ~p bs = (v, v1 = case v of p -> v1 : @@ -450,78 +424,91 @@ tidy1 v (WildPat ty) match_result The case expr for v_i is just: match [v] [(p, [], \ x -> Var v_i)] any_expr -} -tidy1 v (LazyPat pat) match_result - = mkSelectorBinds pat (Var v) `thenDs` \ sel_binds -> - returnDs (WildPat (idType v), - mkCoLetsMatchResult [NonRec b rhs | (b,rhs) <- sel_binds] match_result) +tidy1 v wrap (LazyPat pat) + = do { v' <- newSysLocalDs (idType v) + ; sel_prs <- mkSelectorBinds pat (Var v) + ; let sel_binds = [NonRec b rhs | (b,rhs) <- sel_prs] + ; returnDs (wrap . wrapBind v' v . mkDsLets sel_binds, + WildPat (idType v)) } -- re-express as (ConPat ...) [directly] -tidy1 v (RecPat data_con pat_ty ex_tvs dicts rpats) match_result - | null rpats - = -- Special case for C {}, which can be used for - -- a constructor that isn't declared to have - -- fields at all - returnDs (ConPat data_con pat_ty ex_tvs dicts (map WildPat con_arg_tys'), match_result) - - | otherwise - = returnDs (ConPat data_con pat_ty ex_tvs dicts pats, match_result) +tidy1 v wrap (ConPatOut (L loc con) ex_tvs dicts binds ps pat_ty) + = returnDs (wrap, ConPatOut (L loc con) ex_tvs dicts binds tidy_ps pat_ty) where - pats = map mk_pat tagged_arg_tys - - -- Boring stuff to find the arg-tys of the constructor - (_, inst_tys, _) = splitAlgTyConApp pat_ty - con_arg_tys' = dataConInstOrigArgTys data_con (inst_tys ++ mkTyVarTys ex_tvs) - tagged_arg_tys = con_arg_tys' `zip` (dataConFieldLabels data_con) + tidy_ps = PrefixCon (tidy_con con ex_tvs pat_ty ps) - -- mk_pat picks a WildPat of the appropriate type for absent fields, - -- and the specified pattern for present fields - mk_pat (arg_ty, lbl) = case [pat | (sel_id,pat,_) <- rpats, - recordSelectorFieldLabel sel_id == lbl - ] of - (pat:pats) -> ASSERT( null pats ) - pat - [] -> WildPat arg_ty - -tidy1 v (ListPat ty pats) match_result - = returnDs (list_ConPat, match_result) +tidy1 v wrap (ListPat pats ty) + = returnDs (wrap, unLoc list_ConPat) where - list_ty = mkListTy ty - list_ConPat - = foldr (\ x -> \y -> ConPat consDataCon list_ty [] [] [x, y]) - (ConPat nilDataCon list_ty [] [] []) - pats - -tidy1 v (TuplePat pats boxity) match_result - = returnDs (tuple_ConPat, match_result) + list_ty = mkListTy ty + list_ConPat = foldr (\ x y -> mkPrefixConPat consDataCon [x, y] list_ty) + (mkNilPat list_ty) + pats + +-- Introduce fake parallel array constructors to be able to handle parallel +-- arrays with the existing machinery for constructor pattern +tidy1 v wrap (PArrPat pats ty) + = returnDs (wrap, unLoc parrConPat) + where + arity = length pats + parrConPat = mkPrefixConPat (parrFakeCon arity) pats (mkPArrTy ty) + +tidy1 v wrap (TuplePat pats boxity ty) + = returnDs (wrap, unLoc tuple_ConPat) where arity = length pats - tuple_ConPat - = ConPat (tupleCon boxity arity) - (mkTupleTy boxity arity (map outPatType pats)) [] [] - pats + tuple_ConPat = mkPrefixConPat (tupleCon boxity arity) pats ty -tidy1 v (DictPat dicts methods) match_result +tidy1 v wrap (DictPat dicts methods) = case num_of_d_and_ms of - 0 -> tidy1 v (TuplePat [] Boxed) match_result - 1 -> tidy1 v (head dict_and_method_pats) match_result - _ -> tidy1 v (TuplePat dict_and_method_pats Boxed) match_result + 0 -> tidy1 v wrap (TuplePat [] Boxed unitTy) + 1 -> tidy1 v wrap (unLoc (head dict_and_method_pats)) + _ -> tidy1 v wrap (mkVanillaTuplePat dict_and_method_pats Boxed) where num_of_d_and_ms = length dicts + length methods - dict_and_method_pats = map VarPat (dicts ++ methods) + dict_and_method_pats = map nlVarPat (dicts ++ methods) -- LitPats: we *might* be able to replace these w/ a simpler form -tidy1 v pat@(LitPat lit lit_ty) match_result - = returnDs (tidyLitPat lit pat, match_result) +tidy1 v wrap pat@(LitPat lit) + = returnDs (wrap, unLoc (tidyLitPat lit (noLoc pat))) -- NPats: we *might* be able to replace these w/ a simpler form -tidy1 v pat@(NPat lit lit_ty _) match_result - = returnDs (tidyNPat lit lit_ty pat, match_result) +tidy1 v wrap pat@(NPat lit mb_neg _ lit_ty) + = returnDs (wrap, unLoc (tidyNPat lit mb_neg lit_ty (noLoc pat))) -- and everything else goes through unchanged... -tidy1 v non_interesting_pat match_result - = returnDs (non_interesting_pat, match_result) +tidy1 v wrap non_interesting_pat + = returnDs (wrap, non_interesting_pat) + + +tidy_con data_con ex_tvs pat_ty (PrefixCon ps) = ps +tidy_con data_con ex_tvs pat_ty (InfixCon p1 p2) = [p1,p2] +tidy_con data_con ex_tvs pat_ty (RecCon rpats) + | null rpats + = -- Special case for C {}, which can be used for + -- a constructor that isn't declared to have + -- fields at all + map (noLoc . WildPat) con_arg_tys' + + | otherwise + = map mk_pat tagged_arg_tys + where + -- Boring stuff to find the arg-tys of the constructor + + inst_tys | isVanillaDataCon data_con = tcTyConAppArgs pat_ty -- Newtypes must be opaque + | otherwise = mkTyVarTys ex_tvs + + con_arg_tys' = dataConInstOrigArgTys data_con inst_tys + tagged_arg_tys = con_arg_tys' `zip` dataConFieldLabels data_con + + -- mk_pat picks a WildPat of the appropriate type for absent fields, + -- and the specified pattern for present fields + mk_pat (arg_ty, lbl) = + case [ pat | (sel_id,pat) <- rpats, idName (unLoc sel_id) == lbl] of + (pat:pats) -> ASSERT( null pats ) pat + [] -> noLoc (WildPat arg_ty) \end{code} \noindent @@ -591,48 +578,6 @@ Presumably just a variant on the constructor case (as it is now). %************************************************************************ %* * -%* match on an unmixed block: the real business * -%* * -%************************************************************************ -\subsection[matchUnmixedEqns]{@matchUnmixedEqns@: getting down to business} - -The function @matchUnmixedEqns@ is where the matching stuff sets to -work a block of equations, to which the mixture rule has been applied. -Its arguments and results are the same as for the ``top-level'' @match@. - -\begin{code} -matchUnmixedEqns :: [Id] - -> [EquationInfo] - -> DsM MatchResult - -matchUnmixedEqns [] _ = panic "matchUnmixedEqns: no names" - -matchUnmixedEqns all_vars@(var:vars) eqns_info - | isWildPat first_pat - = ASSERT( all isWildPat column_1_pats ) -- Sanity check - -- Real true variables, just like in matchVar, SLPJ p 94 - -- No binding to do: they'll all be wildcards by now (done in tidy) - match vars remaining_eqns_info - - | isConPat first_pat - = ASSERT( patsAreAllCons column_1_pats ) - matchConFamily all_vars eqns_info - - | isLitPat first_pat - = ASSERT( patsAreAllLits column_1_pats ) - -- see notes in MatchLiteral - -- not worried about the same literal more than once in a column - -- (ToDo: sort this out later) - matchLiterals all_vars eqns_info - - where - first_pat = head column_1_pats - column_1_pats = [pat | EqnInfo _ _ (pat:_) _ <- eqns_info] - remaining_eqns_info = [EqnInfo n ctx pats match_result | EqnInfo n ctx (_:pats) match_result <- eqns_info] -\end{code} - -%************************************************************************ -%* * %* matchWrapper: a convenient way to call @match@ * %* * %************************************************************************ @@ -676,9 +621,8 @@ Call @match@ with all of this information! \end{enumerate} \begin{code} -matchWrapper :: DsMatchKind -- For shadowing warning messages - -> [TypecheckedMatch] -- Matches being desugared - -> String -- Error message if the match fails +matchWrapper :: HsMatchContext Name -- For shadowing warning messages + -> MatchGroup Id -- Matches being desugared -> DsM ([Id], CoreExpr) -- Results \end{code} @@ -705,23 +649,36 @@ one pattern, and match simply only accepts one pattern. JJQC 30-Nov-1997 \begin{code} -matchWrapper kind matches error_string - = getDOptsDs `thenDs` \ dflags -> - flattenMatches kind matches `thenDs` \ (result_ty, eqns_info) -> - let - EqnInfo _ _ arg_pats _ : _ = eqns_info - in - mapDs selectMatchVar arg_pats `thenDs` \ new_vars -> - match_fun dflags new_vars eqns_info `thenDs` \ match_result -> - - mkErrorAppDs pAT_ERROR_ID result_ty error_string `thenDs` \ fail_expr -> - extractMatchResult match_result fail_expr `thenDs` \ result_expr -> - returnDs (new_vars, result_expr) - where match_fun dflags - = case kind of - LambdaMatch | dopt Opt_WarnSimplePatterns dflags -> matchExport - | otherwise -> match - _ -> matchExport +matchWrapper ctxt (MatchGroup matches match_ty) + = do { eqns_info <- mapM mk_eqn_info matches + ; dflags <- getDOptsDs + ; locn <- getSrcSpanDs + ; let ds_ctxt = DsMatchContext ctxt arg_pats locn + error_string = matchContextErrString ctxt + + ; new_vars <- selectMatchVars arg_pats pat_tys + ; match_result <- match_fun dflags ds_ctxt new_vars rhs_ty eqns_info + + ; fail_expr <- mkErrorAppDs pAT_ERROR_ID rhs_ty error_string + ; result_expr <- extractMatchResult match_result fail_expr + ; return (new_vars, result_expr) } + where + arg_pats = map unLoc (hsLMatchPats (head matches)) + n_pats = length arg_pats + (pat_tys, rhs_ty) = splitFunTysN n_pats match_ty + + mk_eqn_info (L _ (Match pats _ grhss)) + = do { let upats = map unLoc pats + ; match_result <- dsGRHSs ctxt upats grhss rhs_ty + ; return (EqnInfo { eqn_wrap = idWrapper, + eqn_pats = upats, + eqn_rhs = match_result}) } + + match_fun dflags ds_ctxt + = case ctxt of + LambdaExpr | dopt Opt_WarnSimplePatterns dflags -> matchCheck ds_ctxt + | otherwise -> match + _ -> matchCheck ds_ctxt \end{code} %************************************************************************ @@ -736,65 +693,41 @@ pattern. It returns an expression. \begin{code} matchSimply :: CoreExpr -- Scrutinee - -> DsMatchKind -- Match kind - -> TypecheckedPat -- Pattern it should match + -> HsMatchContext Name -- Match kind + -> LPat Id -- Pattern it should match -> CoreExpr -- Return this if it matches -> CoreExpr -- Return this if it doesn't -> DsM CoreExpr -matchSimply scrut kind pat result_expr fail_expr - = getSrcLocDs `thenDs` \ locn -> - let - ctx = DsMatchContext kind [pat] locn +matchSimply scrut hs_ctx pat result_expr fail_expr + = let match_result = cantFailMatchResult result_expr + rhs_ty = exprType fail_expr + -- Use exprType of fail_expr, because won't refine in the case of failure! in - matchSinglePat scrut ctx pat match_result `thenDs` \ match_result' -> + matchSinglePat scrut hs_ctx pat rhs_ty match_result `thenDs` \ match_result' -> extractMatchResult match_result' fail_expr -matchSinglePat :: CoreExpr -> DsMatchContext -> TypecheckedPat - -> MatchResult -> DsM MatchResult - -matchSinglePat (Var var) ctx pat match_result - = getDOptsDs `thenDs` \ dflags -> - match_fn dflags [var] [EqnInfo 1 ctx [pat] match_result] - where - match_fn dflags - | dopt Opt_WarnSimplePatterns dflags = matchExport - | otherwise = match +matchSinglePat :: CoreExpr -> HsMatchContext Name -> LPat Id + -> Type -> MatchResult -> DsM MatchResult +matchSinglePat (Var var) hs_ctx (L _ pat) ty match_result + = getDOptsDs `thenDs` \ dflags -> + getSrcSpanDs `thenDs` \ locn -> + let + match_fn dflags + | dopt Opt_WarnSimplePatterns dflags = matchCheck ds_ctx + | otherwise = match + where + ds_ctx = DsMatchContext hs_ctx [pat] locn + in + match_fn dflags [var] ty [EqnInfo { eqn_wrap = idWrapper, + eqn_pats = [pat], + eqn_rhs = match_result }] -matchSinglePat scrut ctx pat match_result - = selectMatchVar pat `thenDs` \ var -> - matchSinglePat (Var var) ctx pat match_result `thenDs` \ match_result' -> +matchSinglePat scrut hs_ctx pat ty match_result + = selectSimpleMatchVarL pat `thenDs` \ var -> + matchSinglePat (Var var) hs_ctx pat ty match_result `thenDs` \ match_result' -> returnDs (adjustMatchResult (bindNonRec var scrut) match_result') \end{code} -%************************************************************************ -%* * -%* flattenMatches : create a list of EquationInfo * -%* * -%************************************************************************ - -\subsection[flattenMatches]{@flattenMatches@: create @[EquationInfo]@} - -This is actually local to @matchWrapper@. - -\begin{code} -flattenMatches - :: DsMatchKind - -> [TypecheckedMatch] - -> DsM (Type, [EquationInfo]) - -flattenMatches kind matches - = mapAndUnzipDs flatten_match (matches `zip` [1..]) `thenDs` \ (result_tys, eqn_infos) -> - let - result_ty = head result_tys - in - ASSERT( all (== result_ty) result_tys ) - returnDs (result_ty, eqn_infos) - where - flatten_match (Match _ pats _ grhss, n) - = dsGRHSs kind pats grhss `thenDs` \ (ty, match_result) -> - getSrcLocDs `thenDs` \ locn -> - returnDs (ty, EqnInfo n (DsMatchContext kind pats locn) pats match_result) -\end{code}