-
%
-% (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}
-module Match ( match, matchExport, matchWrapper, matchSimply ) where
+module Match ( match, matchExport, matchWrapper, matchSimply, matchSinglePat ) where
#include "HsVersions.h"
-import {-# SOURCE #-} DsExpr ( dsExpr )
-import {-# SOURCE #-} DsBinds ( dsBinds )
+import {-# SOURCE #-} DsExpr ( dsExpr, dsLet )
import CmdLineOpts ( opt_WarnIncompletePatterns, opt_WarnOverlappingPatterns,
opt_WarnSimplePatterns
)
import HsSyn
-import TcHsSyn ( TypecheckedPat, TypecheckedMatch,
- TypecheckedHsBinds, TypecheckedHsExpr )
+import TcHsSyn ( TypecheckedPat, TypecheckedMatch )
import DsHsSyn ( outPatType )
-import Check ( check, ExhaustivePat, WarningPat, BoxedString )
+import Check ( check, ExhaustivePat )
import CoreSyn
import CoreUtils ( coreExprType )
import DsMonad
import DsGRHSs ( dsGRHSs )
import DsUtils
-import Id ( idType, dataConFieldLabels,
- dataConArgTys, recordSelectorFieldLabel,
- Id
- )
+import Id ( idType, recordSelectorFieldLabel, Id )
+import DataCon ( dataConFieldLabels, dataConArgTys )
import MatchCon ( matchConFamily )
import MatchLit ( matchLiterals )
-import Name ( Name {--O only-} )
import PrelVals ( pAT_ERROR_ID )
-import Type ( isUnpointedType, splitAlgTyConApp,
+import Type ( isUnLiftedType, splitAlgTyConApp,
Type
)
-import TyVar ( TyVar )
import TysPrim ( intPrimTy, charPrimTy, floatPrimTy, doublePrimTy,
addrPrimTy, wordPrimTy
)
charTy, charDataCon, intTy, intDataCon,
floatTy, floatDataCon, doubleTy, tupleCon,
doubleDataCon, addrTy,
- addrDataCon, wordTy, wordDataCon
+ addrDataCon, wordTy, wordDataCon,
+ mkUnboxedTupleTy, unboxedTupleCon
)
import UniqSet
import Outputable
-> [EquationInfo] -- Info about patterns, etc. (type synonym below)
-> DsM MatchResult -- Desugared result!
-matchExport vars qs@((EqnInfo _ ctx _ (MatchResult _ _ _)) : _)
+matchExport vars qs@((EqnInfo _ ctx _ (MatchResult _ _)) : _)
| incomplete && shadow =
dsShadowWarn ctx eqns_shadow `thenDs` \ () ->
dsIncompleteWarn ctx pats `thenDs` \ () ->
ppr_constraint (var,pats) = sep [ppr var, ptext SLIT("`not_elem`"), ppr pats]
ppr_eqn kind (EqnInfo _ _ pats _) = ppr_shadow_pats kind pats
-
\end{code}
complete_matches (eqn:eqns)
= complete_match eqn `thenDs` \ match_result1 ->
complete_matches eqns `thenDs` \ match_result2 ->
- combineMatchResults match_result1 match_result2
+ returnDs (combineMatchResults match_result1 match_result2)
- complete_match (EqnInfo _ _ [] match_result@(MatchResult _ _ _))
- = returnDs match_result
+ complete_match (EqnInfo _ _ pats match_result)
+ = ASSERT( null pats )
+ returnDs match_result
\end{code}
%************************************************************************
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
+ returnDs (combineMatchResults match_result1 match_result2)
\end{code}
Tidy up the leftmost pattern in an @EquationInfo@, given the variable @v@
-- of new bindings to be added to the front
tidy1 v (VarPat var) match_result
- = returnDs (WildPat (idType var),
- mkCoLetsMatchResult extra_binds match_result)
+ = returnDs (WildPat (idType var), match_result')
where
- extra_binds | v == var = []
- | otherwise = [NonRec var (Var v)]
+ match_result' | v == var = match_result
+ | otherwise = adjustMatchResult (bindNonRec var (Var v)) match_result
tidy1 v (AsPat var pat) match_result
- = tidy1 v pat (mkCoLetsMatchResult extra_binds match_result)
+ = tidy1 v pat match_result'
where
- extra_binds | v == var = []
- | otherwise = [NonRec var (Var v)]
+ 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)
-- re-express <con-something> 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 (RecPat data_con pat_ty tvs dicts rpats) match_result
+ = returnDs (ConPat data_con pat_ty tvs dicts pats, match_result)
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' = dataConArgTys con_id inst_tys
- tagged_arg_tys = con_arg_tys' `zip` (dataConFieldLabels con_id)
+ con_arg_tys' = dataConArgTys 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
where
list_ty = mkListTy ty
list_ConPat
- = foldr (\ x -> \y -> ConPat consDataCon list_ty [x, y])
- (ConPat nilDataCon list_ty [])
+ = foldr (\ x -> \y -> ConPat consDataCon list_ty [] [] [x, y])
+ (ConPat nilDataCon list_ty [] [] [])
pats
-tidy1 v (TuplePat pats) match_result
+tidy1 v (TuplePat pats True{-boxed-}) match_result
= returnDs (tuple_ConPat, match_result)
where
arity = length pats
tuple_ConPat
= ConPat (tupleCon arity)
- (mkTupleTy arity (map outPatType pats))
+ (mkTupleTy arity (map outPatType pats)) [] []
+ pats
+
+tidy1 v (TuplePat pats False{-unboxed-}) match_result
+ = returnDs (tuple_ConPat, match_result)
+ where
+ arity = length pats
+ tuple_ConPat
+ = ConPat (unboxedTupleCon arity)
+ (mkUnboxedTupleTy arity (map outPatType pats)) [] []
pats
tidy1 v (DictPat dicts methods) match_result
= case num_of_d_and_ms of
- 0 -> tidy1 v (TuplePat []) match_result
+ 0 -> tidy1 v (TuplePat [] True) match_result
1 -> tidy1 v (head dict_and_method_pats) match_result
- _ -> tidy1 v (TuplePat dict_and_method_pats) match_result
+ _ -> tidy1 v (TuplePat dict_and_method_pats True) match_result
where
num_of_d_and_ms = length dicts + length methods
dict_and_method_pats = map VarPat (dicts ++ methods)
-- LitPats: the desugarer only sees these at well-known types
tidy1 v pat@(LitPat lit lit_ty) match_result
- | isUnpointedType lit_ty
+ | isUnLiftedType lit_ty
= returnDs (pat, match_result)
| lit_ty == charTy
- = returnDs (ConPat charDataCon charTy [LitPat (mk_char lit) charPrimTy],
+ = returnDs (ConPat charDataCon charTy [] [] [LitPat (mk_char lit) charPrimTy],
match_result)
| otherwise = pprPanic "tidy1:LitPat:" (ppr pat)
= returnDs (better_pat, match_result)
where
better_pat
- | lit_ty == charTy = ConPat charDataCon lit_ty [LitPat (mk_char lit) charPrimTy]
- | lit_ty == intTy = ConPat intDataCon lit_ty [LitPat (mk_int lit) intPrimTy]
- | lit_ty == wordTy = ConPat wordDataCon lit_ty [LitPat (mk_word lit) wordPrimTy]
- | lit_ty == addrTy = ConPat addrDataCon lit_ty [LitPat (mk_addr lit) addrPrimTy]
- | lit_ty == floatTy = ConPat floatDataCon lit_ty [LitPat (mk_float lit) floatPrimTy]
- | lit_ty == doubleTy = ConPat doubleDataCon lit_ty [LitPat (mk_double lit) doublePrimTy]
+ | lit_ty == charTy = ConPat charDataCon lit_ty [] [] [LitPat (mk_char lit) charPrimTy]
+ | lit_ty == intTy = ConPat intDataCon lit_ty [] [] [LitPat (mk_int lit) intPrimTy]
+ | lit_ty == wordTy = ConPat wordDataCon lit_ty [] [] [LitPat (mk_word lit) wordPrimTy]
+ | lit_ty == addrTy = ConPat addrDataCon lit_ty [] [] [LitPat (mk_addr lit) addrPrimTy]
+ | lit_ty == floatTy = ConPat floatDataCon lit_ty [] [] [LitPat (mk_float lit) floatPrimTy]
+ | lit_ty == 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 []
+ | null_str_lit lit = ConPat nilDataCon lit_ty [] [] []
| otherwise = pat
returnDs (var:vars, core_expr)
matchWrapper kind [(GRHSMatch
- (GRHSsAndBindsOut [GRHS [] 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)
+ (GRHSsAndBindsOut [GRHS [ExprStmt expr _]] binds _))] error_string
+ = dsExpr expr `thenDs` \ core_expr ->
+ dsLet binds core_expr `thenDs` \ rhs ->
+ returnDs ([], rhs)
\end{old_code}
And all the rest... (general case)
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 ->
+ = flattenMatches kind matches `thenDs` \ (result_ty, eqns_info) ->
+ let
+ EqnInfo _ _ arg_pats _ : _ = eqns_info
+ in
+ mapDs selectMatchVar 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
matchSimply :: CoreExpr -- Scrutinee
-> DsMatchKind -- Match kind
-> TypecheckedPat -- Pattern it should match
- -> Type -- Type of result
-> 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
+matchSimply scrut kind pat result_expr fail_expr
= getSrcLocDs `thenDs` \ locn ->
let
- ctx = DsMatchContext kind [pat] locn
- eqn_info = EqnInfo 1 ctx [pat] initial_match_result
+ ctx = DsMatchContext kind [pat] locn
+ match_result = cantFailMatchResult result_expr
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 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)
+matchSinglePat :: CoreExpr -> DsMatchContext -> TypecheckedPat
+ -> MatchResult -> DsM MatchResult
-extractMatchResult (MatchResult CantFail _ match_fn) fail_expr
- = returnDs (match_fn (error "It can't fail!"))
+matchSinglePat (Var var) ctx pat match_result
+ = match_fn [var] [EqnInfo 1 ctx [pat] match_result]
+ where
+ match_fn | opt_WarnSimplePatterns = matchExport
+ | otherwise = match
-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))
+matchSinglePat scrut ctx pat match_result
+ = selectMatchVar pat `thenDs` \ var ->
+ matchSinglePat (Var var) ctx pat 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
- -> EqnNo
-> [TypecheckedMatch]
- -> DsM [EquationInfo]
-
-flattenMatches kind n [] = returnDs []
+ -> DsM (Type, [EquationInfo])
-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)
+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 :: [TypecheckedPat] -- Reversed list of patterns encountered so far
- -> EqnNo
- -> TypecheckedMatch
- -> DsM EquationInfo
+ flatten_match (match, eqn_no) = flatten_match_help [] match eqn_no
+
+ flatten_match_help :: [TypecheckedPat] -- Reversed list of patterns encountered so far
+ -> TypecheckedMatch
+ -> EqnNo
+ -> DsM (Type, EquationInfo)
- flatten_match pats_so_far n (PatMatch pat match)
- = flatten_match (pat:pats_so_far) n match
+ flatten_match_help pats_so_far (PatMatch pat match) n
+ = flatten_match_help (pat:pats_so_far) match n
- 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 ->
+ flatten_match_help pats_so_far (GRHSMatch (GRHSsAndBindsOut grhss binds ty)) n
+ = dsGRHSs kind pats grhss `thenDs` \ match_result ->
getSrcLocDs `thenDs` \ locn ->
- returnDs (EqnInfo n (DsMatchContext kind pats locn) pats
- (mkCoLetsMatchResult core_binds match_result))
+ returnDs (ty, EqnInfo n (DsMatchContext kind pats locn) pats
+ (adjustMatchResultDs (dsLet binds) match_result))
+ -- NB: nested dsLet inside matchResult
where
pats = reverse pats_so_far -- They've accumulated in reverse order
- flatten_match pats_so_far n (SimpleMatch expr)
+ flatten_match_help pats_so_far (SimpleMatch expr) n
= 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.
+ returnDs (coreExprType core_expr,
+ EqnInfo n (DsMatchContext kind pats locn) pats
+ (cantFailMatchResult core_expr))
where
pats = reverse pats_so_far -- They've accumulated in reverse order
-
\end{code}
-
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