X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FdeSugar%2FMatch.lhs;h=76263607541cb93ae197c5cf0ea5ff1404d4a898;hb=a3e01707ebc2e7180840b5ab3534f818b43c2873;hp=ed56ab7781f7ebba151efc66dc7332e1b72492c2;hpb=85bd53c951e5504005b9bf9dc3dd884099942f37;p=ghc-hetmet.git diff --git a/ghc/compiler/deSugar/Match.lhs b/ghc/compiler/deSugar/Match.lhs index ed56ab7..7626360 100644 --- a/ghc/compiler/deSugar/Match.lhs +++ b/ghc/compiler/deSugar/Match.lhs @@ -1,66 +1,38 @@ - % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[Main_match]{The @match@ function} \begin{code} -#include "HsVersions.h" +module Match ( match, matchWrapper, matchSimply, matchSinglePat ) where -module Match ( matchExport, match, matchWrapper, matchSimply ) where - -IMP_Ubiq() -#if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ <= 201 -IMPORT_DELOOPER(DsLoop) -- here for paranoia-checking reasons - -- and to break dsExpr/dsBinds-ish loop -#else -import {-# SOURCE #-} DsExpr ( dsExpr ) -import {-# SOURCE #-} DsBinds ( dsBinds ) -#endif +#include "HsVersions.h" -import CmdLineOpts ( opt_WarnIncompletePatterns, opt_WarnOverlappedPatterns, - opt_PprUserLength,opt_WarnSimplePatterns - ) +import CmdLineOpts ( DynFlag(..), dopt ) import HsSyn -import TcHsSyn ( SYN_IE(TypecheckedPat), SYN_IE(TypecheckedMatch), - SYN_IE(TypecheckedHsBinds), SYN_IE(TypecheckedHsExpr) ) -import DsHsSyn ( outPatType, collectTypedPatBinders ) -import Check ( check, SYN_IE(ExhaustivePat), SYN_IE(WarningPat), BoxedString ) +import TcHsSyn ( hsPatType ) +import Check ( check, ExhaustivePat ) import CoreSyn -import CoreUtils ( coreExprType ) +import CoreUtils ( bindNonRec, exprType ) import DsMonad +import DsBinds ( dsHsNestedBinds ) import DsGRHSs ( dsGRHSs ) import DsUtils -import ErrUtils ( SYN_IE(Warning) ) -import FieldLabel ( FieldLabel {- Eq instance -} ) -import Id ( idType, dataConFieldLabels, - dataConArgTys, recordSelectorFieldLabel, - GenId{-instance-}, SYN_IE(Id) - ) +import Id ( idName, idType, Id ) +import DataCon ( dataConFieldLabels, dataConInstOrigArgTys, isVanillaDataCon ) import MatchCon ( matchConFamily ) -import MatchLit ( matchLiterals ) -import Name ( Name {--O only-} ) -import Outputable ( PprStyle(..), Outputable(..), pprQuote ) -import PprType ( GenType{-instance-}, GenTyVar{-ditto-} ) -import Pretty -import PrelVals ( pAT_ERROR_ID ) -import SrcLoc ( noSrcLoc, SrcLoc ) -import Type ( isPrimType, eqTy, getAppDataTyConExpandingDicts, - instantiateTauTy, SYN_IE(Type) - ) -import TyVar ( GenTyVar{-instance Eq-}, SYN_IE(TyVar) ) -import TysPrim ( intPrimTy, charPrimTy, floatPrimTy, doublePrimTy, - addrPrimTy, wordPrimTy - ) -import TysWiredIn ( nilDataCon, consDataCon, mkTupleTy, mkListTy, - charTy, charDataCon, intTy, intDataCon, - floatTy, floatDataCon, doubleTy, tupleCon, - doubleDataCon, stringTy, addrTy, - addrDataCon, wordTy, wordDataCon - ) -import Unique ( Unique{-instance Eq-} ) -import UniqSet -import Util ( panic, pprPanic, assertPanic ) +import MatchLit ( matchLiterals, matchNPlusKPats, matchNPats, tidyLitPat, tidyNPat ) +import PrelInfo ( pAT_ERROR_ID ) +import TcType ( Type, tcTyConAppArgs ) +import Type ( splitFunTysN ) +import TysWiredIn ( consDataCon, mkTupleTy, mkListTy, + tupleCon, parrFakeCon, mkPArrTy ) +import BasicTypes ( Boxity(..) ) +import ListSetOps ( runs ) +import SrcLoc ( noSrcSpan, noLoc, unLoc, Located(..) ) +import Util ( lengthExceeds, notNull ) +import Name ( Name ) +import Outputable \end{code} This function is a wrapper of @match@, it must be called from all the parts where @@ -71,125 +43,98 @@ 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@((EqnInfo _ ctx _ (MatchResult _ _ _)) : _) +matchCheck ctx vars ty qs + = getDOptsDs `thenDs` \ dflags -> + matchCheck_really dflags ctx vars ty qs + +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 = opt_WarnIncompletePatterns && (length pats /= 0) - shadow = opt_WarnOverlappedPatterns && 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 + match vars ty qs + where (pats, eqns_shadow) = check qs + incomplete = dopt Opt_WarnIncompletePatterns dflags + && (notNull pats) + shadow = dopt Opt_WarnOverlappingPatterns dflags + && not (null eqns_shadow) \end{code} -This variable shows the maximun number of lines of output generated for warnings. -It will limit the number of patterns/equations displayed to maximum_output. +This variable shows the maximum number of lines of output generated for warnings. +It will limit the number of patterns/equations displayed to@ maximum_output@. + +(ToDo: add command-line option?) \begin{code} maximum_output = 4 \end{code} -The next two functions creates the warning message. +The next two functions create the warning message. \begin{code} dsShadowWarn :: DsMatchContext -> [EquationInfo] -> DsM () dsShadowWarn ctx@(DsMatchContext kind _ _) qs = dsWarn warn where - warn sty | length qs > maximum_output = - hang (pp_context sty ctx (ptext SLIT("are overlapped"))) - 12 ((vcat $ map (ppr_eqn kind sty) (take maximum_output qs)) - $$ ptext SLIT("...")) - warn sty = - hang (pp_context sty ctx (ptext SLIT("are overlapped"))) - 12 (vcat $ map (ppr_eqn kind sty) qs) + warn | qs `lengthExceeds` maximum_output + = pp_context ctx (ptext SLIT("are overlapped")) + (\ f -> vcat (map (ppr_eqn f kind) (take maximum_output qs)) $$ + 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 where - warn sty | length pats > maximum_output = - hang (pp_context sty ctx (ptext SLIT("are non-exhaustive"))) - 12 (hang (ptext SLIT("Patterns not recognized:")) - 4 ((vcat $ map (ppr_incomplete_pats kind sty) (take maximum_output pats)) - $$ ptext SLIT("..."))) - warn sty = - hang (pp_context sty ctx (ptext SLIT("are non-exhaustive"))) - 12 (hang (ptext SLIT("Patterns not recognized:")) - 4 (vcat $ map (ppr_incomplete_pats kind sty) pats)) - -pp_context sty NoMatchContext msg = ptext SLIT("Warning: Some match(es)") <+> msg - -pp_context sty (DsMatchContext kind pats loc) msg - = hang (hcat [ppr (PprForUser opt_PprUserLength) loc, ptext SLIT(": ")]) - 4 (hang message - 4 (pp_match kind pats)) - where - message = ptext SLIT("Warning: Pattern match(es)") <+> msg - - pp_match (FunMatch fun) pats - = hsep [ptext SLIT("in the definition of function"), ppr sty fun] - - pp_match CaseMatch pats - = hang (ptext SLIT("in a group of case alternatives beginning:")) - 4 (ppr_pats sty pats) - - pp_match PatBindMatch pats - = hang (ptext SLIT("in a pattern binding:")) - 4 (ppr_pats sty pats) - - pp_match LambdaMatch pats - = hang (ptext SLIT("in a lambda abstraction:")) - 4 (ppr_pats sty pats) - - pp_match DoBindMatch pats - = hang (ptext SLIT("in a `do' pattern binding:")) - 4 (ppr_pats sty pats) - - pp_match ListCompMatch pats - = hang (ptext SLIT("in a `list comprension' pattern binding:")) - 4 (ppr_pats sty pats) - - pp_match LetMatch pats - = hang (ptext SLIT("in a `let' pattern binding:")) - 4 (ppr_pats sty pats) - -ppr_pats sty pats = pprQuote sty $ \ sty -> sep (map (ppr sty) pats) - -separator (FunMatch _) = SLIT("=") -separator (CaseMatch) = SLIT("->") -separator (LambdaMatch) = SLIT("->") -separator (PatBindMatch) = panic "When is this used?" -separator (DoBindMatch) = SLIT("<-") -separator (ListCompMatch) = SLIT("<-") -separator (LetMatch) = SLIT("=") - -ppr_shadow_pats kind sty pats = pprQuote sty $ \ sty -> - sep [sep (map (ppr sty) pats), ptext (separator kind), ptext SLIT("...")] + warn = pp_context ctx (ptext SLIT("are non-exhaustive")) + (\f -> hang (ptext SLIT("Patterns not matched:")) + 4 ((vcat $ map (ppr_incomplete_pats kind) + (take maximum_output pats)) + $$ dots)) + + dots | pats `lengthExceeds` maximum_output = ptext SLIT("...") + | otherwise = empty + +pp_context NoMatchContext msg rest_of_msg_fun + = (noSrcSpan, ptext SLIT("Some match(es)") <+> hang msg 8 (rest_of_msg_fun id)) + +pp_context (DsMatchContext kind pats loc) msg rest_of_msg_fun + = (loc, 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) + +ppr_shadow_pats kind pats + = sep [ppr_pats pats, matchSeparator kind, ptext SLIT("...")] -ppr_incomplete_pats kind sty (pats,[]) = pprQuote sty $ \ sty -> - sep [sep (map (ppr sty) pats)] -ppr_incomplete_pats kind sty (pats,constraints) = pprQuote sty $ \ sty -> - sep [sep (map (ppr sty) pats), ptext SLIT("with"), - sep (map (ppr_constraint sty) constraints)] +ppr_incomplete_pats kind (pats,[]) = ppr_pats pats +ppr_incomplete_pats kind (pats,constraints) = + sep [ppr_pats pats, ptext SLIT("with"), + sep (map ppr_constraint constraints)] -ppr_constraint sty (var,pats) = sep [ppr sty var, ptext SLIT("`not_elem`"),ppr sty pats] - -ppr_eqn kind sty (EqnInfo _ _ pats _) = ppr_shadow_pats kind sty pats +ppr_constraint (var,pats) = sep [ppr var, ptext SLIT("`notElem`"), ppr pats] +ppr_eqn prefixF kind eqn = prefixF (ppr_shadow_pats kind (eqn_pats eqn)) \end{code} @@ -246,6 +191,7 @@ 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} @@ -276,7 +222,7 @@ 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} @@ -293,21 +239,16 @@ 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 -> - combineMatchResults match_result1 match_result2 - - complete_match (EqnInfo _ _ [] match_result@(MatchResult _ _ _)) - = returnDs match_result + match_results = [ ASSERT( null (eqn_pats eqn) ) + eqn_rhs eqn + | eqn <- eqns_info ] \end{code} + %************************************************************************ %* * %* match: non-empty rule * @@ -327,42 +268,39 @@ 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 ( (irrefutablePat p1 && irrefutablePat 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 -> - 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 + NPlusKPatOut {} -> matchNPlusKPats vars ty eqns + NPatOut {} -> 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 (NPlusKPatOut {}) (NPlusKPatOut {}) = True +samePatFamily (NPatOut {}) (NPatOut {}) = 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@ @@ -376,7 +314,8 @@ 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} @@ -395,42 +334,80 @@ 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 dsHsNestedBinds + -- and mkSelectorBinds. -- "tidy1" does the interesting stuff, looking at -- one pattern and fiddling the list of bindings. -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), - mkCoLetsMatchResult extra_binds match_result) - where - extra_binds | v == var = [] - | otherwise = [NonRec var (Var v)] - -tidy1 v (AsPat var pat) match_result - = tidy1 v pat (mkCoLetsMatchResult extra_binds match_result) - where - extra_binds | v == var = [] - | otherwise = [NonRec var (Var v)] + -- + -- POST CONDITION: head pattern in the EqnInfo is + -- WildPat + -- ConPat + -- NPat + -- LitPat + -- NPlusKPat + -- but no other + +tidyEqnInfo v eqn@(EqnInfo { eqn_pats = pat : pats, eqn_rhs = rhs }) + = tidy1 v pat rhs `thenDs` \ (pat', rhs') -> + returnDs (eqn { eqn_pats = pat' : pats, eqn_rhs = rhs' }) + +tidy1 :: Id -- The Id being scrutinised + -> Pat Id -- The pattern against which it is to be matched + -> MatchResult -- What to do afterwards + -> DsM (Pat Id, -- Equivalent pattern + MatchResult) -- Extra bindings around what to do afterwards + +-- 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 (ParPat pat) wrap = tidy1 v (unLoc pat) wrap +tidy1 v (SigPatOut pat _) wrap = tidy1 v (unLoc pat) wrap +tidy1 v (WildPat ty) wrap = returnDs (WildPat ty, wrap) + + -- case v of { x -> mr[] } + -- = case v of { _ -> let x=v in mr[] } +tidy1 v (VarPat var) rhs + = returnDs (WildPat (idType var), bindOneInMatchResult var v rhs) + +tidy1 v (VarPatOut var binds) rhs + = do { prs <- dsHsNestedBinds binds + ; return (WildPat (idType var), + bindOneInMatchResult var v $ + mkCoLetMatchResult (Rec prs) rhs) } + + -- case v of { x@p -> mr[] } + -- = case v of { p -> let x=v in mr[] } +tidy1 v (AsPat (L _ var) pat) rhs + = tidy1 v (unLoc pat) (bindOneInMatchResult var v rhs) -tidy1 v (WildPat ty) match_result - = returnDs (WildPat ty, match_result) {- now, here we handle lazy patterns: tidy1 v ~p bs = (v, v1 = case v of p -> v1 : @@ -443,126 +420,98 @@ 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 (LazyPat pat) rhs + = do { v' <- newSysLocalDs (idType v) + ; sel_prs <- mkSelectorBinds pat (Var v) + ; let sel_binds = [NonRec b rhs | (b,rhs) <- sel_prs] + ; returnDs (WildPat (idType v), + bindOneInMatchResult v' v $ + mkCoLetsMatchResult sel_binds rhs) } -- re-express as (ConPat ...) [directly] -tidy1 v (ConOpPat pat1 id pat2 ty) match_result - = returnDs (ConPat id ty [pat1, pat2], match_result) - -tidy1 v (RecPat con_id pat_ty rpats) match_result - = returnDs (ConPat con_id pat_ty pats, match_result) +tidy1 v (ConPatOut (L loc con) ex_tvs dicts binds ps pat_ty) rhs + = returnDs (ConPatOut (L loc con) ex_tvs dicts binds tidy_ps pat_ty, rhs) where - pats = map mk_pat tagged_arg_tys - - -- Boring stuff to find the arg-tys of the constructor - (_, inst_tys, _) = getAppDataTyConExpandingDicts pat_ty - con_arg_tys' = dataConArgTys con_id inst_tys - tagged_arg_tys = con_arg_tys' `zip` (dataConFieldLabels con_id) + tidy_ps = PrefixCon (tidy_con con 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 (ListPat pats ty) rhs + = returnDs (unLoc list_ConPat, rhs) + where + 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 (PArrPat pats ty) rhs + = returnDs (unLoc parrConPat, rhs) 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) match_result - = returnDs (tuple_ConPat, match_result) + arity = length pats + parrConPat = mkPrefixConPat (parrFakeCon arity) pats (mkPArrTy ty) + +tidy1 v (TuplePat pats boxity) rhs + = returnDs (unLoc tuple_ConPat, rhs) where arity = length pats - tuple_ConPat - = ConPat (tupleCon arity) - (mkTupleTy arity (map outPatType pats)) - pats + tuple_ConPat = mkPrefixConPat (tupleCon boxity arity) pats + (mkTupleTy boxity arity (map hsPatType pats)) -tidy1 v (DictPat dicts methods) match_result +tidy1 v (DictPat dicts methods) rhs = case num_of_d_and_ms of - 0 -> tidy1 v (TuplePat []) match_result - 1 -> tidy1 v (head dict_and_method_pats) match_result - _ -> tidy1 v (TuplePat dict_and_method_pats) match_result + 0 -> tidy1 v (TuplePat [] Boxed) rhs + 1 -> tidy1 v (unLoc (head dict_and_method_pats)) rhs + _ -> tidy1 v (TuplePat dict_and_method_pats Boxed) rhs where num_of_d_and_ms = length dicts + length methods - dict_and_method_pats = map VarPat (dicts ++ methods) - - --- deeply ugly mangling for some (common) NPats/LitPats - --- LitPats: the desugarer only sees these at well-known types - -tidy1 v pat@(LitPat lit lit_ty) match_result - | isPrimType lit_ty - = returnDs (pat, match_result) - - | lit_ty `eqTy` charTy - = returnDs (ConPat charDataCon charTy [LitPat (mk_char lit) charPrimTy], - match_result) + dict_and_method_pats = map nlVarPat (dicts ++ methods) - | otherwise = pprPanic "tidy1:LitPat:" (ppr PprDebug pat) - where - mk_char (HsChar c) = HsCharPrim c +-- LitPats: we *might* be able to replace these w/ a simpler form +tidy1 v pat@(LitPat lit) rhs + = returnDs (unLoc (tidyLitPat lit (noLoc pat)), rhs) -- NPats: we *might* be able to replace these w/ a simpler form +tidy1 v pat@(NPatOut lit lit_ty _) rhs + = returnDs (unLoc (tidyNPat lit lit_ty (noLoc pat)), rhs) +-- and everything else goes through unchanged... -tidy1 v pat@(NPat lit lit_ty _) match_result - = returnDs (better_pat, match_result) - where - better_pat - | lit_ty `eqTy` charTy = ConPat charDataCon lit_ty [LitPat (mk_char lit) charPrimTy] - | lit_ty `eqTy` intTy = ConPat intDataCon lit_ty [LitPat (mk_int lit) intPrimTy] - | lit_ty `eqTy` wordTy = ConPat wordDataCon lit_ty [LitPat (mk_word lit) wordPrimTy] - | lit_ty `eqTy` addrTy = ConPat addrDataCon lit_ty [LitPat (mk_addr lit) addrPrimTy] - | lit_ty `eqTy` floatTy = ConPat floatDataCon lit_ty [LitPat (mk_float lit) floatPrimTy] - | lit_ty `eqTy` doubleTy = ConPat doubleDataCon lit_ty [LitPat (mk_double lit) doublePrimTy] - - -- Convert the literal pattern "" to the constructor pattern []. - | null_str_lit lit = ConPat nilDataCon lit_ty [] - - | otherwise = pat - - mk_int (HsInt i) = HsIntPrim i - mk_int l@(HsLitLit s) = l - - mk_char (HsChar c) = HsCharPrim c - mk_char l@(HsLitLit s) = l - - mk_word l@(HsLitLit s) = l - - mk_addr l@(HsLitLit s) = l - - mk_float (HsInt i) = HsFloatPrim (fromInteger i) - mk_float (HsFrac f) = HsFloatPrim f - mk_float l@(HsLitLit s) = l +tidy1 v non_interesting_pat rhs + = returnDs (non_interesting_pat, rhs) - mk_double (HsInt i) = HsDoublePrim (fromInteger i) - mk_double (HsFrac f) = HsDoublePrim f - mk_double l@(HsLitLit s) = l - null_str_lit (HsString s) = _NULL_ s - null_str_lit other_lit = False +tidy_con data_con pat_ty (PrefixCon ps) = ps +tidy_con data_con pat_ty (InfixCon p1 p2) = [p1,p2] +tidy_con data_con 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' --- and everything else goes through unchanged... + | otherwise + = ASSERT( isVanillaDataCon data_con ) + -- We're in a record case, so the data con must be vanilla + -- and hence no existentials to worry about + map mk_pat tagged_arg_tys + where + -- Boring stuff to find the arg-tys of the constructor + + inst_tys = tcTyConAppArgs pat_ty -- Newtypes must be opaque + con_arg_tys' = dataConInstOrigArgTys data_con inst_tys + tagged_arg_tys = con_arg_tys' `zip` dataConFieldLabels data_con -tidy1 v non_interesting_pat match_result - = returnDs (non_interesting_pat, match_result) + -- 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} -PREVIOUS matchTwiddled STUFF: +\noindent +{\bf Previous @matchTwiddled@ stuff:} Now we get to the only interesting part; note: there are choices for translation [from Simon's notes]; translation~1: @@ -628,47 +577,6 @@ 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 - | irrefutablePat first_pat - = ASSERT( irrefutablePats column_1_pats ) -- Sanity check - -- Real true variables, just like in matchVar, SLPJ p 94 - 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@ * %* * %************************************************************************ @@ -712,74 +620,63 @@ 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} - a special case for the common ...: - just one Match - lots of (all?) unfailable pats - e.g., - f x y z = .... - - This special case have been ``undone'' due to problems with the new warnings - messages (Check.lhs.check). We need there the name of the variables to be able to - print later the equation. JJQC 30-11-97 - -\begin{old_code} -matchWrapper kind [(PatMatch (VarPat var) match)] error_string - = matchWrapper kind [match] error_string `thenDs` \ (vars, core_expr) -> - returnDs (var:vars, core_expr) - -matchWrapper kind [(PatMatch (WildPat ty) match)] error_string - = newSysLocalDs ty `thenDs` \ var -> - matchWrapper kind [match] error_string `thenDs` \ (vars, core_expr) -> - returnDs (var:vars, core_expr) - -matchWrapper kind [(GRHSMatch - (GRHSsAndBindsOut [OtherwiseGRHS expr _] binds _))] error_string - = dsBinds False{-don't auto-scc-} binds `thenDs` \ core_binds -> - dsExpr expr `thenDs` \ core_expr -> - returnDs ([], mkCoLetsAny core_binds core_expr) -\end{old_code} - - And all the rest... (general case) - - There is one small problem with the Lambda Patterns, when somebody writes something similar to: +\begin{verbatim} (\ (x:xs) -> ...) +\end{verbatim} he/she don't want a warning about incomplete patterns, that is done with - the flag opt_WarnSimplePatterns. - This problem also appears in the : - do patterns, but if the do can fail it creates another equation if the match can - fail (see DsExpr.doDo function) - let patterns, are treated by matchSimply - List Comprension Patterns, are treated by matchSimply also - -We can't call matchSimply with Lambda patterns, due to lambda patterns can have more than + the flag @opt_WarnSimplePatterns@. + This problem also appears in the: +\begin{itemize} +\item @do@ patterns, but if the @do@ can fail + it creates another equation if the match can fail + (see @DsExpr.doDo@ function) +\item @let@ patterns, are treated by @matchSimply@ + List Comprension Patterns, are treated by @matchSimply@ also +\end{itemize} + +We can't call @matchSimply@ with Lambda patterns, +due to the fact that lambda patterns can have more than one pattern, and match simply only accepts one pattern. JJQC 30-Nov-1997 - -\begin{code} - -matchWrapper kind matches error_string - = flattenMatches kind 1 matches `thenDs` \ eqns_info@(EqnInfo _ _ arg_pats (MatchResult _ result_ty _) : _) -> - - selectMatchVars arg_pats `thenDs` \ new_vars -> - match_fun 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 = case kind of - LambdaMatch | opt_WarnSimplePatterns -> matchExport - | otherwise -> match - _ -> matchExport +\begin{code} +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_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} %************************************************************************ @@ -794,91 +691,38 @@ pattern. It returns an expression. \begin{code} matchSimply :: CoreExpr -- Scrutinee - -> DsMatchKind -- Match kind - -> TypecheckedPat -- Pattern it should match - -> Type -- Type of result + -> HsMatchContext Name -- Match kind + -> LPat Id -- Pattern it should match -> CoreExpr -- Return this if it matches - -> CoreExpr -- Return this if it does + -> CoreExpr -- Return this if it doesn't -> DsM CoreExpr -matchSimply (Var var) kind pat result_ty result_expr fail_expr - = getSrcLocDs `thenDs` \ locn -> +matchSimply scrut kind pat result_expr fail_expr + = getSrcSpanDs `thenDs` \ locn -> let - ctx = DsMatchContext kind [pat] locn - eqn_info = EqnInfo 1 ctx [pat] initial_match_result + ctx = DsMatchContext kind [unLoc pat] locn + 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 - match_fun [var] [eqn_info] `thenDs` \ match_result -> - extractMatchResult match_result fail_expr - where - initial_match_result = MatchResult CantFail result_ty (\ ignore -> result_expr) - match_fun = if opt_WarnSimplePatterns - then matchExport - else match + matchSinglePat scrut ctx pat rhs_ty match_result `thenDs` \ match_result' -> + extractMatchResult match_result' fail_expr -matchSimply scrut_expr kind pat result_ty result_expr msg - = newSysLocalDs (outPatType pat) `thenDs` \ scrut_var -> - matchSimply (Var scrut_var) kind pat result_ty result_expr msg `thenDs` \ expr -> - returnDs (Let (NonRec scrut_var scrut_expr) expr) - -extractMatchResult (MatchResult CantFail _ match_fn) fail_expr - = returnDs (match_fn (error "It can't fail!")) - -extractMatchResult (MatchResult CanFail result_ty match_fn) fail_expr - = mkFailurePair result_ty `thenDs` \ (fail_bind_fn, if_it_fails) -> - returnDs (Let (fail_bind_fn fail_expr) (match_fn if_it_fails)) -\end{code} - -%************************************************************************ -%* * -%* flattenMatches : create a list of EquationInfo * -%* * -%************************************************************************ -\subsection[flattenMatches]{@flattenMatches@: create @[EquationInfo]@} - -This is actually local to @matchWrapper@. - -\begin{code} -flattenMatches - :: DsMatchKind - -> EqnNo - -> [TypecheckedMatch] - -> DsM [EquationInfo] - -flattenMatches kind n [] = returnDs [] - -flattenMatches kind n (match : matches) - = flatten_match [] n match `thenDs` \ eqn_info -> - flattenMatches kind (n+1) matches `thenDs` \ eqn_infos -> - returnDs (eqn_info : eqn_infos) +matchSinglePat :: CoreExpr -> DsMatchContext -> LPat Id + -> Type -> MatchResult -> DsM MatchResult +matchSinglePat (Var var) ctx pat ty match_result + = getDOptsDs `thenDs` \ dflags -> + match_fn dflags [var] ty [EqnInfo { eqn_pats = [unLoc pat], + eqn_rhs = match_result }] where - flatten_match :: [TypecheckedPat] -- Reversed list of patterns encountered so far - -> EqnNo - -> TypecheckedMatch - -> DsM EquationInfo - - flatten_match pats_so_far n (PatMatch pat match) - = flatten_match (pat:pats_so_far) n match - - flatten_match pats_so_far n (GRHSMatch (GRHSsAndBindsOut grhss binds ty)) - = dsBinds False{-don't auto-scc-} binds `thenDs` \ core_binds -> - dsGRHSs ty kind pats grhss `thenDs` \ match_result -> - getSrcLocDs `thenDs` \ locn -> - returnDs (EqnInfo n (DsMatchContext kind pats locn) pats - (mkCoLetsMatchResult core_binds match_result)) - where - pats = reverse pats_so_far -- They've accumulated in reverse order - - flatten_match pats_so_far n (SimpleMatch expr) - = dsExpr expr `thenDs` \ core_expr -> - getSrcLocDs `thenDs` \ locn -> - returnDs (EqnInfo n (DsMatchContext kind pats locn) pats - (MatchResult CantFail (coreExprType core_expr) - (\ ignore -> core_expr))) - - -- the matching can't fail, so we won't generate an error message. - where - pats = reverse pats_so_far -- They've accumulated in reverse order - + match_fn dflags + | dopt Opt_WarnSimplePatterns dflags = matchCheck ctx + | otherwise = match + +matchSinglePat scrut ctx pat ty match_result + = selectSimpleMatchVarL pat `thenDs` \ var -> + matchSinglePat (Var var) ctx pat ty match_result `thenDs` \ match_result' -> + returnDs (adjustMatchResult (bindNonRec var scrut) match_result') \end{code}