\section[MatchLit]{Pattern-matching literal patterns}
\begin{code}
-module MatchLit ( matchLiterals ) where
+module MatchLit ( dsLit, matchLiterals ) where
#include "HsVersions.h"
import {-# SOURCE #-} Match ( match )
import {-# SOURCE #-} DsExpr ( dsExpr )
-import HsSyn ( HsLit(..), OutPat(..), HsExpr(..) )
-import TcHsSyn ( TypecheckedHsExpr, TypecheckedPat )
-import CoreSyn ( Expr(..), Bind(..) )
-import Id ( Id )
-
import DsMonad
+import DsCCall ( resultWrapper )
import DsUtils
-import Const ( mkMachInt, Literal(..) )
-import PrimRep ( PrimRep(IntRep) )
+import HsSyn ( HsLit(..), Pat(..), HsExpr(..) )
+import TcHsSyn ( TypecheckedPat )
+import Id ( Id )
+import CoreSyn
+import TyCon ( tyConDataCons )
+import TcType ( tcSplitTyConApp, isIntegerTy )
+
+import PrelNames ( ratioTyConKey )
+import Unique ( hasKey )
+import Literal ( mkMachInt, Literal(..) )
import Maybes ( catMaybes )
-import Type ( Type, isUnLiftedType )
+import Type ( isUnLiftedType )
import Panic ( panic, assertPanic )
+import Maybe ( isJust )
+import Ratio ( numerator, denominator )
\end{code}
+%************************************************************************
+%* *
+ Desugaring literals
+ [used to be in DsExpr, but DsMeta needs it,
+ and it's nice to avoid a loop]
+%* *
+%************************************************************************
+
+We give int/float literals type @Integer@ and @Rational@, respectively.
+The typechecker will (presumably) have put \tr{from{Integer,Rational}s}
+around them.
+
+ToDo: put in range checks for when converting ``@i@''
+(or should that be in the typechecker?)
+
+For numeric literals, we try to detect there use at a standard type
+(@Int@, @Float@, etc.) are directly put in the right constructor.
+[NB: down with the @App@ conversion.]
+
+See also below where we look for @DictApps@ for \tr{plusInt}, etc.
+
+\begin{code}
+dsLit :: HsLit -> DsM CoreExpr
+dsLit (HsChar c) = returnDs (mkCharExpr c)
+dsLit (HsCharPrim c) = returnDs (mkLit (MachChar c))
+dsLit (HsString str) = mkStringLitFS str
+dsLit (HsStringPrim s) = returnDs (mkLit (MachStr s))
+dsLit (HsInteger i) = mkIntegerExpr i
+dsLit (HsInt i) = returnDs (mkIntExpr i)
+dsLit (HsIntPrim i) = returnDs (mkIntLit i)
+dsLit (HsFloatPrim f) = returnDs (mkLit (MachFloat f))
+dsLit (HsDoublePrim d) = returnDs (mkLit (MachDouble d))
+dsLit (HsLitLit str ty)
+ = resultWrapper ty `thenDs` \ (maybe_ty, wrap_fn) ->
+ ASSERT( isJust maybe_ty )
+ let (Just rep_ty) = maybe_ty in
+ returnDs (wrap_fn (mkLit (MachLitLit str rep_ty)))
+
+dsLit (HsRat r ty)
+ = mkIntegerExpr (numerator r) `thenDs` \ num ->
+ mkIntegerExpr (denominator r) `thenDs` \ denom ->
+ returnDs (mkConApp ratio_data_con [Type integer_ty, num, denom])
+ where
+ (ratio_data_con, integer_ty)
+ = case tcSplitTyConApp ty of
+ (tycon, [i_ty]) -> ASSERT(isIntegerTy i_ty && tycon `hasKey` ratioTyConKey)
+ (head (tyConDataCons tycon), i_ty)
+\end{code}
+
+%************************************************************************
+%* *
+ Pattern matching on literals
+%* *
+%************************************************************************
+
\begin{code}
matchLiterals :: [Id]
-> [EquationInfo]
the alts---here we use @match_prims_used@.
\begin{code}
-matchLiterals all_vars@(var:vars) eqns_info@(EqnInfo n ctx (LitPat literal lit_ty : ps1) _ : eqns)
+matchLiterals all_vars@(var:vars) eqns_info@(EqnInfo n ctx (LitPat literal : ps1) _ : eqns)
= -- GENERATE THE ALTS
match_prims_used vars eqns_info `thenDs` \ prim_alts ->
where
match_prims_used _ [{-no more eqns-}] = returnDs []
- match_prims_used vars eqns_info@(EqnInfo n ctx ((LitPat literal lit_ty):ps1) _ : eqns)
+ match_prims_used vars eqns_info@(EqnInfo n ctx (pat@(LitPat literal):ps1) _ : eqns)
= let
(shifted_eqns_for_this_lit, eqns_not_for_this_lit)
- = partitionEqnsByLit Nothing literal eqns_info
+ = partitionEqnsByLit pat eqns_info
in
-- recursive call to make other alts...
match_prims_used vars eqns_not_for_this_lit `thenDs` \ rest_of_alts ->
-- now do the business to make the alt for _this_ LitPat ...
match vars shifted_eqns_for_this_lit `thenDs` \ match_result ->
returnDs (
- (mk_core_lit lit_ty literal, match_result)
+ (mk_core_lit literal, match_result)
: rest_of_alts
)
where
- mk_core_lit :: Type -> HsLit -> Literal
-
- mk_core_lit ty (HsIntPrim i) = mkMachInt i
- mk_core_lit ty (HsCharPrim c) = MachChar c
- mk_core_lit ty (HsStringPrim s) = MachStr s
- mk_core_lit ty (HsFloatPrim f) = MachFloat f
- mk_core_lit ty (HsDoublePrim d) = MachDouble d
- mk_core_lit ty (HsLitLit s) = ASSERT(isUnLiftedType ty)
- MachLitLit s (panic "MatchLit.matchLiterals:mk_core_lit:HsLitLit; typePrimRep???")
- mk_core_lit ty other = panic "matchLiterals:mk_core_lit:unhandled"
+ mk_core_lit :: HsLit -> Literal
+
+ mk_core_lit (HsIntPrim i) = mkMachInt i
+ mk_core_lit (HsCharPrim c) = MachChar c
+ mk_core_lit (HsStringPrim s) = MachStr s
+ mk_core_lit (HsFloatPrim f) = MachFloat f
+ mk_core_lit (HsDoublePrim d) = MachDouble d
+ mk_core_lit (HsLitLit s ty) = ASSERT(isUnLiftedType ty)
+ MachLitLit s ty
+ mk_core_lit other = panic "matchLiterals:mk_core_lit:unhandled"
\end{code}
\begin{code}
-matchLiterals all_vars@(var:vars) eqns_info@(EqnInfo n ctx ((NPat literal lit_ty eq_chk):ps1) _ : eqns)
+matchLiterals all_vars@(var:vars)
+ eqns_info@(EqnInfo n ctx (pat@(NPatOut literal lit_ty eq_chk):ps1) _ : eqns)
= let
(shifted_eqns_for_this_lit, eqns_not_for_this_lit)
- = partitionEqnsByLit Nothing literal eqns_info
+ = partitionEqnsByLit pat eqns_info
in
- dsExpr (HsApp eq_chk (HsVar var)) `thenDs` \ pred_expr ->
- match vars shifted_eqns_for_this_lit `thenDs` \ inner_match_result ->
+ dsExpr (HsApp eq_chk (HsVar var)) `thenDs` \ pred_expr ->
+ match vars shifted_eqns_for_this_lit `thenDs` \ inner_match_result ->
let
match_result1 = mkGuardedMatchResult pred_expr inner_match_result
in
\begin{code}
-matchLiterals all_vars@(var:vars) eqns_info@(EqnInfo n ctx ((NPlusKPat master_n k ty ge sub):ps1) _ : eqns)
+matchLiterals all_vars@(var:vars) eqns_info@(EqnInfo n ctx (pat@(NPlusKPatOut master_n k ge sub):ps1) _ : eqns)
= let
(shifted_eqns_for_this_lit, eqns_not_for_this_lit)
- = partitionEqnsByLit (Just master_n) k eqns_info
+ = partitionEqnsByLit pat eqns_info
in
match vars shifted_eqns_for_this_lit `thenDs` \ inner_match_result ->
returnDs (combineMatchResults match_result1 match_result2)
\end{code}
-Given a blob of LitPats/NPats, we want to split them into those
+Given a blob of @LitPat@s/@NPat@s, we want to split them into those
that are ``same''/different as one we are looking at. We need to know
-whether we're looking at a LitPat/NPat, and what literal we're after.
+whether we're looking at a @LitPat@/@NPat@, and what literal we're after.
\begin{code}
-partitionEqnsByLit :: Maybe Id -- (Just v) for N-plus-K patterns, where v
- -- is the "master" variable;
- -- Nothing for NPats and LitPats
- -> HsLit
+partitionEqnsByLit :: TypecheckedPat
-> [EquationInfo]
-> ([EquationInfo], -- These ones are for this lit, AND
-- they've been "shifted" by stripping
-- are exactly as fed in.
)
-partitionEqnsByLit nPlusK lit eqns
+partitionEqnsByLit master_pat eqns
= ( \ (xs,ys) -> (catMaybes xs, catMaybes ys))
- (unzip (map (partition_eqn nPlusK lit) eqns))
+ (unzip (map (partition_eqn master_pat) eqns))
where
- partition_eqn :: Maybe Id -> HsLit -> EquationInfo ->
- (Maybe EquationInfo, Maybe EquationInfo)
+ partition_eqn :: TypecheckedPat -> EquationInfo -> (Maybe EquationInfo, Maybe EquationInfo)
- partition_eqn Nothing lit (EqnInfo n ctx (LitPat k _ : remaining_pats) match_result)
- | lit `eq_lit` k = (Just (EqnInfo n ctx remaining_pats match_result), Nothing)
+ partition_eqn (LitPat k1) (EqnInfo n ctx (LitPat k2 : remaining_pats) match_result)
+ | k1 == k2 = (Just (EqnInfo n ctx remaining_pats match_result), Nothing)
-- NB the pattern is stripped off the EquationInfo
- partition_eqn Nothing lit (EqnInfo n ctx (NPat k _ _ : remaining_pats) match_result)
- | lit `eq_lit` k = (Just (EqnInfo n ctx remaining_pats match_result), Nothing)
+ partition_eqn (NPatOut k1 _ _) (EqnInfo n ctx (NPatOut k2 _ _ : remaining_pats) match_result)
+ | k1 == k2 = (Just (EqnInfo n ctx remaining_pats match_result), Nothing)
-- NB the pattern is stripped off the EquationInfo
- partition_eqn (Just master_n) lit (EqnInfo n ctx (NPlusKPat n' k _ _ _ : remaining_pats) match_result)
- | lit `eq_lit` k = (Just (EqnInfo n ctx remaining_pats new_match_result), Nothing)
+ partition_eqn (NPlusKPatOut master_n k1 _ _)
+ (EqnInfo n ctx (NPlusKPatOut n' k2 _ _ : remaining_pats) match_result)
+ | k1 == k2 = (Just (EqnInfo n ctx remaining_pats new_match_result), Nothing)
-- NB the pattern is stripped off the EquationInfo
where
new_match_result | master_n == n' = match_result
- | otherwise = mkCoLetsMatchResult [NonRec n' (Var master_n)] match_result
+ | otherwise = mkCoLetsMatchResult
+ [NonRec n' (Var master_n)] match_result
- -- Wild-card patterns, which will only show up in the shadows, go into both groups
- partition_eqn nPlusK lit eqn@(EqnInfo n ctx (WildPat _ : remaining_pats) match_result)
+ -- Wild-card patterns, which will only show up in the shadows,
+ -- go into both groups
+ partition_eqn master_pat eqn@(EqnInfo n ctx (WildPat _ : remaining_pats) match_result)
= (Just (EqnInfo n ctx remaining_pats match_result), Just eqn)
-- Default case; not for this pattern
- partition_eqn nPlusK lit eqn = (Nothing, Just eqn)
-
--- ToDo: meditate about this equality business...
-
-eq_lit (HsInt i1) (HsInt i2) = i1 == i2
-eq_lit (HsFrac f1) (HsFrac f2) = f1 == f2
-
-eq_lit (HsIntPrim i1) (HsIntPrim i2) = i1 == i2
-eq_lit (HsFloatPrim f1) (HsFloatPrim f2) = f1 == f2
-eq_lit (HsDoublePrim d1) (HsDoublePrim d2) = d1 == d2
-eq_lit (HsChar c1) (HsChar c2) = c1 == c2
-eq_lit (HsCharPrim c1) (HsCharPrim c2) = c1 == c2
-eq_lit (HsString s1) (HsString s2) = s1 == s2
-eq_lit (HsStringPrim s1) (HsStringPrim s2) = s1 == s2
-eq_lit (HsLitLit s1) (HsLitLit s2) = s1 == s2 -- ToDo: ??? (dubious)
-eq_lit other1 other2 = panic "matchLiterals:eq_lit"
+ partition_eqn master_pat eqn = (Nothing, Just eqn)
\end{code}
+
projects / ghc-hetmet.git / blobdiff