\section[DsExpr]{Matching expressions (Exprs)}
\begin{code}
-module DsExpr ( dsExpr, dsLet, dsLit ) where
+module DsExpr ( dsExpr, dsLExpr, dsLocalBinds, dsValBinds, dsLit ) where
#include "HsVersions.h"
-
-import Match ( matchWrapper, matchSimply )
-import MatchLit ( dsLit )
-import DsBinds ( dsMonoBinds, AutoScc(..) )
+import Match ( matchWrapper, matchSimply, matchSinglePat )
+import MatchLit ( dsLit, dsOverLit )
+import DsBinds ( dsLHsBinds, dsCoercion )
import DsGRHSs ( dsGuarded )
-import DsCCall ( dsCCall )
import DsListComp ( dsListComp, dsPArrComp )
-import DsUtils ( mkErrorAppDs, mkStringLit, mkConsExpr, mkNilExpr)
+import DsUtils ( mkErrorAppDs, mkStringExpr, mkConsExpr, mkNilExpr,
+ extractMatchResult, cantFailMatchResult, matchCanFail,
+ mkCoreTupTy, selectSimpleMatchVarL, lookupEvidence )
+import DsArrows ( dsProcExpr )
import DsMonad
#ifdef GHCI
import DsMeta ( dsBracket )
#endif
-import HsSyn ( failureFreePat,
- HsExpr(..), Pat(..), HsLit(..), ArithSeqInfo(..),
- Stmt(..), HsMatchContext(..), HsDoContext(..),
- Match(..), HsBinds(..), MonoBinds(..), HsConDetails(..),
- mkSimpleMatch
- )
-import TcHsSyn ( TypecheckedHsExpr, TypecheckedHsBinds, TypecheckedStmt, hsPatType )
+import HsSyn
+import TcHsSyn ( hsPatType, mkVanillaTuplePat )
-- NB: The desugarer, which straddles the source and Core worlds, sometimes
-- needs to see source types (newtypes etc), and sometimes not
-- So WATCH OUT; check each use of split*Ty functions.
-- Sigh. This is a pain.
-import TcType ( tcSplitAppTy, tcSplitFunTys, tcTyConAppArgs,
- tcSplitTyConApp, isUnLiftedType, Type )
-import Type ( splitFunTys )
+import TcType ( tcSplitAppTy, tcSplitFunTys, tcTyConAppTyCon,
+ tcTyConAppArgs, isUnLiftedType, Type, mkAppTy )
+import Type ( funArgTy, splitFunTys, isUnboxedTupleType, mkFunTy )
import CoreSyn
import CoreUtils ( exprType, mkIfThenElse, bindNonRec )
-import FieldLabel ( FieldLabel, fieldLabelTyCon )
import CostCentre ( mkUserCC )
-import Id ( Id, idType, recordSelectorFieldLabel )
+import Id ( Id, idType, idName, idDataCon )
import PrelInfo ( rEC_CON_ERROR_ID, iRREFUT_PAT_ERROR_ID )
import DataCon ( DataCon, dataConWrapId, dataConFieldLabels, dataConInstOrigArgTys )
-import DataCon ( isExistentialDataCon )
-import TyCon ( tyConDataCons )
+import DataCon ( isVanillaDataCon )
+import TyCon ( FieldLabel, tyConDataCons )
import TysWiredIn ( tupleCon )
import BasicTypes ( RecFlag(..), Boxity(..), ipNameName )
-import PrelNames ( toPName )
+import PrelNames ( toPName,
+ returnMName, bindMName, thenMName, failMName,
+ mfixName )
+import SrcLoc ( Located(..), unLoc, getLoc, noLoc )
import Util ( zipEqual, zipWithEqual )
+import Bag ( bagToList )
import Outputable
import FastString
\end{code}
%************************************************************************
%* *
-\subsection{dsLet}
+ dsLocalBinds, dsValBinds
%* *
%************************************************************************
-@dsLet@ is a match-result transformer, taking the @MatchResult@ for the body
-and transforming it into one for the let-bindings enclosing the body.
-
-This may seem a bit odd, but (source) let bindings can contain unboxed
-binds like
-\begin{verbatim}
- C x# = e
-\end{verbatim}
-This must be transformed to a case expression and, if the type has
-more than one constructor, may fail.
-
\begin{code}
-dsLet :: TypecheckedHsBinds -> CoreExpr -> DsM CoreExpr
-
-dsLet EmptyBinds body
- = returnDs body
+dsLocalBinds :: HsLocalBinds Id -> CoreExpr -> DsM CoreExpr
+dsLocalBinds EmptyLocalBinds body = return body
+dsLocalBinds (HsValBinds binds) body = dsValBinds binds body
+dsLocalBinds (HsIPBinds binds) body = dsIPBinds binds body
+
+-------------------------
+dsValBinds :: HsValBinds Id -> CoreExpr -> DsM CoreExpr
+dsValBinds (ValBindsOut binds _) body = foldrDs ds_val_bind body binds
+
+-------------------------
+dsIPBinds (IPBinds ip_binds dict_binds) body
+ = do { prs <- dsLHsBinds dict_binds
+ ; let inner = foldr (\(x,r) e -> Let (NonRec x r) e) body prs
+ ; foldrDs ds_ip_bind inner ip_binds }
+ where
+ ds_ip_bind (L _ (IPBind n e)) body
+ = dsLExpr e `thenDs` \ e' ->
+ returnDs (Let (NonRec (ipNameName n) e') body)
-dsLet (ThenBinds b1 b2) body
- = dsLet b2 body `thenDs` \ body' ->
- dsLet b1 body'
-
+-------------------------
+ds_val_bind :: (RecFlag, LHsBinds Id) -> CoreExpr -> DsM CoreExpr
-- Special case for bindings which bind unlifted variables
-- We need to do a case right away, rather than building
-- a tuple and doing selections.
--- Silently ignore INLINE pragmas...
-dsLet bind@(MonoBind (AbsBinds [] [] exports inlines binds) sigs is_rec) body
- | or [isUnLiftedType (idType g) | (_, g, l) <- exports]
- = ASSERT (case is_rec of {NonRecursive -> True; other -> False})
- -- Unlifted bindings are always non-recursive
- -- and are always a Fun or Pat monobind
- --
+-- Silently ignore INLINE and SPECIALISE pragmas...
+ds_val_bind (NonRecursive, hsbinds) body
+ | [L _ (AbsBinds [] [] exports binds)] <- bagToList hsbinds,
+ (L loc bind : null_binds) <- bagToList binds,
+ or [isUnLiftedType (idType g) | (_, g, _, _) <- exports]
+ || isBangHsBind bind
+ = let
+ body_w_exports = foldr bind_export body exports
+ bind_export (tvs, g, l, _) body = ASSERT( null tvs )
+ bindNonRec g (Var l) body
+ in
+ ASSERT (null null_binds)
+ -- Non-recursive, non-overloaded bindings only come in ones
-- ToDo: in some bizarre case it's conceivable that there
-- could be dict binds in the 'binds'. (See the notes
-- below. Then pattern-match would fail. Urk.)
- case binds of
- FunMonoBind fun _ matches loc
- -> putSrcLocDs loc $
- matchWrapper (FunRhs fun) matches `thenDs` \ (args, rhs) ->
+ putSrcSpanDs loc $
+ case bind of
+ FunBind { fun_id = L _ fun, fun_matches = matches, fun_co_fn = co_fn }
+ -> matchWrapper (FunRhs (idName fun)) matches `thenDs` \ (args, rhs) ->
ASSERT( null args ) -- Functions aren't lifted
+ ASSERT( isIdCoercion co_fn )
returnDs (bindNonRec fun rhs body_w_exports)
- PatMonoBind pat grhss loc
- -> putSrcLocDs loc $
- dsGuarded grhss `thenDs` \ rhs ->
+ PatBind {pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty = ty }
+ -> putSrcSpanDs loc $
+ dsGuarded grhss ty `thenDs` \ rhs ->
mk_error_app pat `thenDs` \ error_expr ->
matchSimply rhs PatBindRhs pat body_w_exports error_expr
- other -> pprPanic "dsLet: unlifted" (ppr bind $$ ppr body)
+ other -> pprPanic "dsLet: unlifted" (pprLHsBinds hsbinds $$ ppr body)
where
- body_w_exports = foldr bind_export body exports
- bind_export (tvs, g, l) body = ASSERT( null tvs )
- bindNonRec g (Var l) body
-
- mk_error_app pat = mkErrorAppDs iRREFUT_PAT_ERROR_ID
+ mk_error_app pat = mkErrorAppDs iRREFUT_PAT_ERROR_ID
(exprType body)
(showSDoc (ppr pat))
--- Ordinary case for bindings
-dsLet (MonoBind binds sigs is_rec) body
- = dsMonoBinds NoSccs binds [] `thenDs` \ prs ->
- returnDs (Let (Rec prs) body)
+-- Ordinary case for bindings; none should be unlifted
+ds_val_bind (is_rec, binds) body
+ = do { prs <- dsLHsBinds binds
+ ; ASSERT( not (any (isUnLiftedType . idType . fst) prs) )
+ case prs of
+ [] -> return body
+ other -> return (Let (Rec prs) body) }
-- Use a Rec regardless of is_rec.
- -- Why? Because it allows the MonoBinds to be all
+ -- Why? Because it allows the binds to be all
-- mixed up, which is what happens in one rare case
-- Namely, for an AbsBind with no tyvars and no dicts,
-- but which does have dictionary bindings.
%************************************************************************
\begin{code}
-dsExpr :: TypecheckedHsExpr -> DsM CoreExpr
+dsLExpr :: LHsExpr Id -> DsM CoreExpr
+dsLExpr (L loc e) = putSrcSpanDs loc $ dsExpr e
-dsExpr (HsPar x) = dsExpr x
-dsExpr (HsVar var) = returnDs (Var var)
-dsExpr (HsIPVar ip) = returnDs (Var (ipNameName ip))
-dsExpr (HsLit lit) = dsLit lit
--- HsOverLit has been gotten rid of by the type checker
+dsExpr :: HsExpr Id -> DsM CoreExpr
+
+dsExpr (HsPar e) = dsLExpr e
+dsExpr (ExprWithTySigOut e _) = dsLExpr e
+dsExpr (HsVar var) = returnDs (Var var)
+dsExpr (HsIPVar ip) = returnDs (Var (ipNameName ip))
+dsExpr (HsLit lit) = dsLit lit
+dsExpr (HsOverLit lit) = dsOverLit lit
+
+dsExpr (NegApp expr neg_expr)
+ = do { core_expr <- dsLExpr expr
+ ; core_neg <- dsExpr neg_expr
+ ; return (core_neg `App` core_expr) }
dsExpr expr@(HsLam a_Match)
- = matchWrapper LambdaExpr [a_Match] `thenDs` \ (binders, matching_code) ->
+ = matchWrapper LambdaExpr a_Match `thenDs` \ (binders, matching_code) ->
returnDs (mkLams binders matching_code)
dsExpr expr@(HsApp fun arg)
- = dsExpr fun `thenDs` \ core_fun ->
- dsExpr arg `thenDs` \ core_arg ->
+ = dsLExpr fun `thenDs` \ core_fun ->
+ dsLExpr arg `thenDs` \ core_arg ->
returnDs (core_fun `App` core_arg)
\end{code}
\begin{code}
dsExpr (OpApp e1 op _ e2)
- = dsExpr op `thenDs` \ core_op ->
+ = dsLExpr op `thenDs` \ core_op ->
-- for the type of y, we need the type of op's 2nd argument
- dsExpr e1 `thenDs` \ x_core ->
- dsExpr e2 `thenDs` \ y_core ->
+ dsLExpr e1 `thenDs` \ x_core ->
+ dsLExpr e2 `thenDs` \ y_core ->
returnDs (mkApps core_op [x_core, y_core])
dsExpr (SectionL expr op)
- = dsExpr op `thenDs` \ core_op ->
+ = dsLExpr op `thenDs` \ core_op ->
-- for the type of y, we need the type of op's 2nd argument
let
(x_ty:y_ty:_, _) = splitFunTys (exprType core_op)
-- Must look through an implicit-parameter type;
-- newtype impossible; hence Type.splitFunTys
in
- dsExpr expr `thenDs` \ x_core ->
+ dsLExpr expr `thenDs` \ x_core ->
newSysLocalDs x_ty `thenDs` \ x_id ->
newSysLocalDs y_ty `thenDs` \ y_id ->
returnDs (bindNonRec x_id x_core $
Lam y_id (mkApps core_op [Var x_id, Var y_id]))
--- dsExpr (SectionR op expr) -- \ x -> op x expr
+-- dsLExpr (SectionR op expr) -- \ x -> op x expr
dsExpr (SectionR op expr)
- = dsExpr op `thenDs` \ core_op ->
+ = dsLExpr op `thenDs` \ core_op ->
-- for the type of x, we need the type of op's 2nd argument
let
(x_ty:y_ty:_, _) = splitFunTys (exprType core_op)
-- See comment with SectionL
in
- dsExpr expr `thenDs` \ y_core ->
+ dsLExpr expr `thenDs` \ y_core ->
newSysLocalDs x_ty `thenDs` \ x_id ->
newSysLocalDs y_ty `thenDs` \ y_id ->
returnDs (bindNonRec y_id y_core $
Lam x_id (mkApps core_op [Var x_id, Var y_id]))
-dsExpr (HsCCall lbl args may_gc is_asm result_ty)
- = mapDs dsExpr args `thenDs` \ core_args ->
- dsCCall lbl core_args may_gc is_asm result_ty
- -- dsCCall does all the unboxification, etc.
-
dsExpr (HsSCC cc expr)
- = dsExpr expr `thenDs` \ core_expr ->
+ = dsLExpr expr `thenDs` \ core_expr ->
getModuleDs `thenDs` \ mod_name ->
returnDs (Note (SCC (mkUserCC cc mod_name)) core_expr)
--- special case to handle unboxed tuple patterns.
-dsExpr (HsCase discrim matches src_loc)
- | all ubx_tuple_match matches
- = putSrcLocDs src_loc $
- dsExpr discrim `thenDs` \ core_discrim ->
+-- hdaume: core annotation
+
+dsExpr (HsCoreAnn fs expr)
+ = dsLExpr expr `thenDs` \ core_expr ->
+ returnDs (Note (CoreNote $ unpackFS fs) core_expr)
+
+-- Special case to handle unboxed tuple patterns; they can't appear nested
+-- The idea is that
+-- case e of (# p1, p2 #) -> rhs
+-- should desugar to
+-- case e of (# x1, x2 #) -> ... match p1, p2 ...
+-- NOT
+-- let x = e in case x of ....
+--
+-- But there may be a big
+-- let fail = ... in case e of ...
+-- wrapping the whole case, which complicates matters slightly
+-- It all seems a bit fragile. Test is dsrun013.
+
+dsExpr (HsCase discrim matches@(MatchGroup _ ty))
+ | isUnboxedTupleType (funArgTy ty)
+ = dsLExpr discrim `thenDs` \ core_discrim ->
matchWrapper CaseAlt matches `thenDs` \ ([discrim_var], matching_code) ->
- case matching_code of
- Case (Var x) bndr alts | x == discrim_var ->
- returnDs (Case core_discrim bndr alts)
- _ -> panic ("dsExpr: tuple pattern:\n" ++ showSDoc (ppr matching_code))
- where
- ubx_tuple_match (Match [TuplePat ps Unboxed] _ _) = True
- ubx_tuple_match _ = False
+ let
+ scrungle (Case (Var x) bndr ty alts)
+ | x == discrim_var = Case core_discrim bndr ty alts
+ scrungle (Let binds body) = Let binds (scrungle body)
+ scrungle other = panic ("dsLExpr: tuple pattern:\n" ++ showSDoc (ppr other))
+ in
+ returnDs (scrungle matching_code)
-dsExpr (HsCase discrim matches src_loc)
- = putSrcLocDs src_loc $
- dsExpr discrim `thenDs` \ core_discrim ->
- matchWrapper CaseAlt matches `thenDs` \ ([discrim_var], matching_code) ->
+dsExpr (HsCase discrim matches)
+ = dsLExpr discrim `thenDs` \ core_discrim ->
+ matchWrapper CaseAlt matches `thenDs` \ ([discrim_var], matching_code) ->
returnDs (bindNonRec discrim_var core_discrim matching_code)
dsExpr (HsLet binds body)
- = dsExpr body `thenDs` \ body' ->
- dsLet binds body'
-
-dsExpr (HsWith expr binds is_with)
- = dsExpr expr `thenDs` \ expr' ->
- foldlDs dsIPBind expr' binds
- where
- dsIPBind body (n, e)
- = dsExpr e `thenDs` \ e' ->
- returnDs (Let (NonRec (ipNameName n) e') body)
+ = dsLExpr body `thenDs` \ body' ->
+ dsLocalBinds binds body'
-- We need the `ListComp' form to use `deListComp' (rather than the "do" form)
-- because the interpretation of `stmts' depends on what sort of thing it is.
--
-dsExpr (HsDo ListComp stmts _ result_ty src_loc)
+dsExpr (HsDo ListComp stmts body result_ty)
= -- Special case for list comprehensions
- putSrcLocDs src_loc $
- dsListComp stmts elt_ty
+ dsListComp stmts body elt_ty
where
- (_, [elt_ty]) = tcSplitTyConApp result_ty
+ [elt_ty] = tcTyConAppArgs result_ty
+
+dsExpr (HsDo DoExpr stmts body result_ty)
+ = dsDo stmts body result_ty
-dsExpr (HsDo DoExpr stmts ids result_ty src_loc)
- = putSrcLocDs src_loc $
- dsDo DoExpr stmts ids result_ty
+dsExpr (HsDo (MDoExpr tbl) stmts body result_ty)
+ = dsMDo tbl stmts body result_ty
-dsExpr (HsDo PArrComp stmts _ result_ty src_loc)
+dsExpr (HsDo PArrComp stmts body result_ty)
= -- Special case for array comprehensions
- putSrcLocDs src_loc $
- dsPArrComp stmts elt_ty
+ dsPArrComp (map unLoc stmts) body elt_ty
where
- (_, [elt_ty]) = tcSplitTyConApp result_ty
+ [elt_ty] = tcTyConAppArgs result_ty
-dsExpr (HsIf guard_expr then_expr else_expr src_loc)
- = putSrcLocDs src_loc $
- dsExpr guard_expr `thenDs` \ core_guard ->
- dsExpr then_expr `thenDs` \ core_then ->
- dsExpr else_expr `thenDs` \ core_else ->
+dsExpr (HsIf guard_expr then_expr else_expr)
+ = dsLExpr guard_expr `thenDs` \ core_guard ->
+ dsLExpr then_expr `thenDs` \ core_then ->
+ dsLExpr else_expr `thenDs` \ core_else ->
returnDs (mkIfThenElse core_guard core_then core_else)
\end{code}
% ~~~~~~~~~~~~~~~~~~~~~~~~~~~
\begin{code}
dsExpr (TyLam tyvars expr)
- = dsExpr expr `thenDs` \ core_expr ->
+ = dsLExpr expr `thenDs` \ core_expr ->
returnDs (mkLams tyvars core_expr)
dsExpr (TyApp expr tys)
- = dsExpr expr `thenDs` \ core_expr ->
+ = dsLExpr expr `thenDs` \ core_expr ->
returnDs (mkTyApps core_expr tys)
\end{code}
= go xs
where
go [] = returnDs (mkNilExpr ty)
- go (x:xs) = dsExpr x `thenDs` \ core_x ->
+ go (x:xs) = dsLExpr x `thenDs` \ core_x ->
go xs `thenDs` \ core_xs ->
returnDs (mkConsExpr ty core_x core_xs)
-- we create a list from the array elements and convert them into a list using
-- `PrelPArr.toP'
--
--- * the main disadvantage to this scheme is that `toP' traverses the list
+-- * the main disadvantage to this scheme is that `toP' traverses the list
-- twice: once to determine the length and a second time to put to elements
-- into the array; this inefficiency could be avoided by exposing some of
-- the innards of `PrelPArr' to the compiler (ie, have a `PrelPArrBase') so
returnDs (mkApps (Var toP) [Type ty, coreList])
dsExpr (ExplicitTuple expr_list boxity)
- = mapDs dsExpr expr_list `thenDs` \ core_exprs ->
+ = mappM dsLExpr expr_list `thenDs` \ core_exprs ->
returnDs (mkConApp (tupleCon boxity (length expr_list))
(map (Type . exprType) core_exprs ++ core_exprs))
-dsExpr (ArithSeqOut expr (From from))
+dsExpr (ArithSeq expr (From from))
= dsExpr expr `thenDs` \ expr2 ->
- dsExpr from `thenDs` \ from2 ->
+ dsLExpr from `thenDs` \ from2 ->
returnDs (App expr2 from2)
-dsExpr (ArithSeqOut expr (FromTo from two))
+dsExpr (ArithSeq expr (FromTo from two))
= dsExpr expr `thenDs` \ expr2 ->
- dsExpr from `thenDs` \ from2 ->
- dsExpr two `thenDs` \ two2 ->
+ dsLExpr from `thenDs` \ from2 ->
+ dsLExpr two `thenDs` \ two2 ->
returnDs (mkApps expr2 [from2, two2])
-dsExpr (ArithSeqOut expr (FromThen from thn))
+dsExpr (ArithSeq expr (FromThen from thn))
= dsExpr expr `thenDs` \ expr2 ->
- dsExpr from `thenDs` \ from2 ->
- dsExpr thn `thenDs` \ thn2 ->
+ dsLExpr from `thenDs` \ from2 ->
+ dsLExpr thn `thenDs` \ thn2 ->
returnDs (mkApps expr2 [from2, thn2])
-dsExpr (ArithSeqOut expr (FromThenTo from thn two))
+dsExpr (ArithSeq expr (FromThenTo from thn two))
= dsExpr expr `thenDs` \ expr2 ->
- dsExpr from `thenDs` \ from2 ->
- dsExpr thn `thenDs` \ thn2 ->
- dsExpr two `thenDs` \ two2 ->
+ dsLExpr from `thenDs` \ from2 ->
+ dsLExpr thn `thenDs` \ thn2 ->
+ dsLExpr two `thenDs` \ two2 ->
returnDs (mkApps expr2 [from2, thn2, two2])
-dsExpr (PArrSeqOut expr (FromTo from two))
+dsExpr (PArrSeq expr (FromTo from two))
= dsExpr expr `thenDs` \ expr2 ->
- dsExpr from `thenDs` \ from2 ->
- dsExpr two `thenDs` \ two2 ->
+ dsLExpr from `thenDs` \ from2 ->
+ dsLExpr two `thenDs` \ two2 ->
returnDs (mkApps expr2 [from2, two2])
-dsExpr (PArrSeqOut expr (FromThenTo from thn two))
+dsExpr (PArrSeq expr (FromThenTo from thn two))
= dsExpr expr `thenDs` \ expr2 ->
- dsExpr from `thenDs` \ from2 ->
- dsExpr thn `thenDs` \ thn2 ->
- dsExpr two `thenDs` \ two2 ->
+ dsLExpr from `thenDs` \ from2 ->
+ dsLExpr thn `thenDs` \ thn2 ->
+ dsLExpr two `thenDs` \ two2 ->
returnDs (mkApps expr2 [from2, thn2, two2])
-dsExpr (PArrSeqOut expr _)
+dsExpr (PArrSeq expr _)
= panic "DsExpr.dsExpr: Infinite parallel array!"
-- the parser shouldn't have generated it and the renamer and typechecker
-- shouldn't have let it through
constructor @C@, setting all of @C@'s fields to bottom.
\begin{code}
-dsExpr (RecordConOut data_con con_expr rbinds)
+dsExpr (RecordCon (L _ data_con_id) con_expr rbinds)
= dsExpr con_expr `thenDs` \ con_expr' ->
let
(arg_tys, _) = tcSplitFunTys (exprType con_expr')
-- A newtype in the corner should be opaque;
-- hence TcType.tcSplitFunTys
- mk_arg (arg_ty, lbl)
- = case [rhs | (sel_id,rhs) <- rbinds,
- lbl == recordSelectorFieldLabel sel_id] of
+ mk_arg (arg_ty, lbl) -- Selector id has the field label as its name
+ = case [rhs | (L _ sel_id, rhs) <- rbinds, lbl == idName sel_id] of
(rhs:rhss) -> ASSERT( null rhss )
- dsExpr rhs
+ dsLExpr rhs
[] -> mkErrorAppDs rEC_CON_ERROR_ID arg_ty (showSDoc (ppr lbl))
unlabelled_bottom arg_ty = mkErrorAppDs rEC_CON_ERROR_ID arg_ty ""
- labels = dataConFieldLabels data_con
+ labels = dataConFieldLabels (idDataCon data_con_id)
+ -- The data_con_id is guaranteed to be the wrapper id of the constructor
in
(if null labels
- then mapDs unlabelled_bottom arg_tys
- else mapDs mk_arg (zipEqual "dsExpr:RecordCon" arg_tys labels))
+ then mappM unlabelled_bottom arg_tys
+ else mappM mk_arg (zipEqual "dsExpr:RecordCon" arg_tys labels))
`thenDs` \ con_args ->
returnDs (mkApps con_expr' con_args)
dictionaries.
\begin{code}
-dsExpr (RecordUpdOut record_expr record_in_ty record_out_ty [])
- = dsExpr record_expr
+dsExpr (RecordUpd record_expr [] record_in_ty record_out_ty)
+ = dsLExpr record_expr
-dsExpr expr@(RecordUpdOut record_expr record_in_ty record_out_ty rbinds)
- = getSrcLocDs `thenDs` \ src_loc ->
- dsExpr record_expr `thenDs` \ record_expr' ->
+dsExpr expr@(RecordUpd record_expr rbinds record_in_ty record_out_ty)
+ = dsLExpr record_expr `thenDs` \ record_expr' ->
-- Desugar the rbinds, and generate let-bindings if
-- necessary so that we don't lose sharing
let
in_inst_tys = tcTyConAppArgs record_in_ty -- Newtype opaque
out_inst_tys = tcTyConAppArgs record_out_ty -- Newtype opaque
+ in_out_ty = mkFunTy record_in_ty record_out_ty
mk_val_arg field old_arg_id
- = case [rhs | (sel_id, rhs) <- rbinds,
- field == recordSelectorFieldLabel sel_id] of
+ = case [rhs | (L _ sel_id, rhs) <- rbinds, field == idName sel_id] of
(rhs:rest) -> ASSERT(null rest) rhs
- [] -> HsVar old_arg_id
+ [] -> nlHsVar old_arg_id
mk_alt con
= newSysLocalsDs (dataConInstOrigArgTys con in_inst_tys) `thenDs` \ arg_ids ->
- -- This call to dataConArgTys won't work for existentials
+ -- This call to dataConInstOrigArgTys won't work for existentials
+ -- but existentials don't have record types anyway
let
val_args = zipWithEqual "dsExpr:RecordUpd" mk_val_arg
(dataConFieldLabels con) arg_ids
- rhs = foldl HsApp (TyApp (HsVar (dataConWrapId con)) out_inst_tys)
- val_args
+ rhs = foldl (\a b -> nlHsApp a b)
+ (noLoc $ TyApp (nlHsVar (dataConWrapId con))
+ out_inst_tys)
+ val_args
in
- returnDs (mkSimpleMatch [ConPatOut con (PrefixCon (map VarPat arg_ids)) record_in_ty [] []]
- rhs
- record_out_ty
- src_loc)
+ returnDs (mkSimpleMatch [noLoc $ ConPatOut (noLoc con) [] [] emptyLHsBinds
+ (PrefixCon (map nlVarPat arg_ids)) record_in_ty]
+ rhs)
in
-- Record stuff doesn't work for existentials
-- The type checker checks for this, but we need
-- worry only about the constructors that are to be updated
- ASSERT2( all (not . isExistentialDataCon) cons_to_upd, ppr expr )
+ ASSERT2( all isVanillaDataCon cons_to_upd, ppr expr )
-- It's important to generate the match with matchWrapper,
-- and the right hand sides with applications of the wrapper Id
-- so that everything works when we are doing fancy unboxing on the
-- constructor aguments.
- mapDs mk_alt cons_to_upd `thenDs` \ alts ->
- matchWrapper RecUpd alts `thenDs` \ ([discrim_var], matching_code) ->
+ mappM mk_alt cons_to_upd `thenDs` \ alts ->
+ matchWrapper RecUpd (MatchGroup alts in_out_ty) `thenDs` \ ([discrim_var], matching_code) ->
returnDs (bindNonRec discrim_var record_expr' matching_code)
where
updated_fields :: [FieldLabel]
- updated_fields = [recordSelectorFieldLabel sel_id | (sel_id,_) <- rbinds]
+ updated_fields = [ idName sel_id | (L _ sel_id,_) <- rbinds]
- -- Get the type constructor from the first field label,
+ -- Get the type constructor from the record_in_ty
-- so that we are sure it'll have all its DataCons
-- (In GHCI, it's possible that some TyCons may not have all
-- their constructors, in a module-loop situation.)
- tycon = fieldLabelTyCon (head updated_fields)
+ tycon = tcTyConAppTyCon record_in_ty
data_cons = tyConDataCons tycon
cons_to_upd = filter has_all_fields data_cons
complicated; reminiscent of fully-applied constructors.
\begin{code}
dsExpr (DictLam dictvars expr)
- = dsExpr expr `thenDs` \ core_expr ->
+ = dsLExpr expr `thenDs` \ core_expr ->
returnDs (mkLams dictvars core_expr)
------------------
dsExpr (DictApp expr dicts) -- becomes a curried application
- = dsExpr expr `thenDs` \ core_expr ->
+ = dsLExpr expr `thenDs` \ core_expr ->
returnDs (foldl (\f d -> f `App` (Var d)) core_expr dicts)
+
+dsExpr (HsCoerce co_fn e) = dsCoercion co_fn (dsExpr e)
\end{code}
Here is where we desugar the Template Haskell brackets and escapes
#ifdef GHCI /* Only if bootstrapping */
dsExpr (HsBracketOut x ps) = dsBracket x ps
-dsExpr (HsSplice n e) = pprPanic "dsExpr:splice" (ppr e)
+dsExpr (HsSpliceE s) = pprPanic "dsExpr:splice" (ppr s)
#endif
+-- Arrow notation extension
+dsExpr (HsProc pat cmd) = dsProcExpr pat cmd
\end{code}
#ifdef DEBUG
-- HsSyn constructs that just shouldn't be here:
dsExpr (ExprWithTySig _ _) = panic "dsExpr:ExprWithTySig"
-dsExpr (ArithSeqIn _) = panic "dsExpr:ArithSeqIn"
-dsExpr (PArrSeqIn _) = panic "dsExpr:PArrSeqIn"
#endif
\end{code}
%--------------------------------------------------------------------
-Basically does the translation given in the Haskell~1.3 report:
+Desugar 'do' and 'mdo' expressions (NOT list comprehensions, they're
+handled in DsListComp). Basically does the translation given in the
+Haskell 98 report:
\begin{code}
-dsDo :: HsDoContext
- -> [TypecheckedStmt]
- -> [Id] -- id for: [return,fail,>>=,>>]
- -> Type -- Element type; the whole expression has type (m t)
+dsDo :: [LStmt Id]
+ -> LHsExpr Id
+ -> Type -- Type of the whole expression
-> DsM CoreExpr
-dsDo do_or_lc stmts ids@[return_id, fail_id, bind_id, then_id] result_ty
- = let
- (_, b_ty) = tcSplitAppTy result_ty -- result_ty must be of the form (m b)
- is_do = case do_or_lc of
- DoExpr -> True
- _ -> False
-
- -- For ExprStmt, see the comments near HsExpr.Stmt about
- -- exactly what ExprStmts mean!
- --
- -- In dsDo we can only see DoStmt and ListComp (no guards)
-
- go [ResultStmt expr locn]
- | is_do = do_expr expr locn
- | otherwise = do_expr expr locn `thenDs` \ expr2 ->
- returnDs (mkApps (Var return_id) [Type b_ty, expr2])
-
- go (ExprStmt expr a_ty locn : stmts)
- | is_do -- Do expression
- = do_expr expr locn `thenDs` \ expr2 ->
- go stmts `thenDs` \ rest ->
- returnDs (mkApps (Var then_id) [Type a_ty, Type b_ty, expr2, rest])
-
- | otherwise -- List comprehension
- = do_expr expr locn `thenDs` \ expr2 ->
- go stmts `thenDs` \ rest ->
- let
- msg = "Pattern match failure in do expression, " ++ showSDoc (ppr locn)
- in
- mkStringLit msg `thenDs` \ core_msg ->
- returnDs (mkIfThenElse expr2 rest
- (App (App (Var fail_id) (Type b_ty)) core_msg))
+dsDo stmts body result_ty
+ = go (map unLoc stmts)
+ where
+ go [] = dsLExpr body
- go (LetStmt binds : stmts )
- = go stmts `thenDs` \ rest ->
- dsLet binds rest
-
- go (BindStmt pat expr locn : stmts)
- = putSrcLocDs locn $
- dsExpr expr `thenDs` \ expr2 ->
- let
- a_ty = hsPatType pat
- fail_expr = HsApp (TyApp (HsVar fail_id) [b_ty])
- (HsLit (HsString (mkFastString msg)))
- msg = "Pattern match failure in do expression, " ++ showSDoc (ppr locn)
- main_match = mkSimpleMatch [pat]
- (HsDo do_or_lc stmts ids result_ty locn)
- result_ty locn
- the_matches
- | failureFreePat pat = [main_match]
- | otherwise =
- [ main_match
- , mkSimpleMatch [WildPat a_ty] fail_expr result_ty locn
- ]
- in
- matchWrapper (DoCtxt do_or_lc) the_matches `thenDs` \ (binders, matching_code) ->
- returnDs (mkApps (Var bind_id) [Type a_ty, Type b_ty, expr2,
- mkLams binders matching_code])
- in
- go stmts
+ go (ExprStmt rhs then_expr _ : stmts)
+ = do { rhs2 <- dsLExpr rhs
+ ; then_expr2 <- dsExpr then_expr
+ ; rest <- go stmts
+ ; returnDs (mkApps then_expr2 [rhs2, rest]) }
+
+ go (LetStmt binds : stmts)
+ = do { rest <- go stmts
+ ; dsLocalBinds binds rest }
+
+ go (BindStmt pat rhs bind_op fail_op : stmts)
+ = do { body <- go stmts
+ ; var <- selectSimpleMatchVarL pat
+ ; match <- matchSinglePat (Var var) (StmtCtxt DoExpr) pat
+ result_ty (cantFailMatchResult body)
+ ; match_code <- handle_failure pat match fail_op
+ ; rhs' <- dsLExpr rhs
+ ; bind_op' <- dsExpr bind_op
+ ; returnDs (mkApps bind_op' [rhs', Lam var match_code]) }
+
+ -- In a do expression, pattern-match failure just calls
+ -- the monadic 'fail' rather than throwing an exception
+ handle_failure pat match fail_op
+ | matchCanFail match
+ = do { fail_op' <- dsExpr fail_op
+ ; fail_msg <- mkStringExpr (mk_fail_msg pat)
+ ; extractMatchResult match (App fail_op' fail_msg) }
+ | otherwise
+ = extractMatchResult match (error "It can't fail")
+
+mk_fail_msg pat = "Pattern match failure in do expression at " ++
+ showSDoc (ppr (getLoc pat))
+\end{code}
+Translation for RecStmt's:
+-----------------------------
+We turn (RecStmt [v1,..vn] stmts) into:
+
+ (v1,..,vn) <- mfix (\~(v1,..vn). do stmts
+ return (v1,..vn))
+
+\begin{code}
+dsMDo :: PostTcTable
+ -> [LStmt Id]
+ -> LHsExpr Id
+ -> Type -- Type of the whole expression
+ -> DsM CoreExpr
+
+dsMDo tbl stmts body result_ty
+ = go (map unLoc stmts)
where
- do_expr expr locn = putSrcLocDs locn (dsExpr expr)
+ (m_ty, b_ty) = tcSplitAppTy result_ty -- result_ty must be of the form (m b)
+ mfix_id = lookupEvidence tbl mfixName
+ return_id = lookupEvidence tbl returnMName
+ bind_id = lookupEvidence tbl bindMName
+ then_id = lookupEvidence tbl thenMName
+ fail_id = lookupEvidence tbl failMName
+ ctxt = MDoExpr tbl
+
+ go [] = dsLExpr body
+
+ go (LetStmt binds : stmts)
+ = do { rest <- go stmts
+ ; dsLocalBinds binds rest }
+
+ go (ExprStmt rhs _ rhs_ty : stmts)
+ = do { rhs2 <- dsLExpr rhs
+ ; rest <- go stmts
+ ; returnDs (mkApps (Var then_id) [Type rhs_ty, Type b_ty, rhs2, rest]) }
+
+ go (BindStmt pat rhs _ _ : stmts)
+ = do { body <- go stmts
+ ; var <- selectSimpleMatchVarL pat
+ ; match <- matchSinglePat (Var var) (StmtCtxt ctxt) pat
+ result_ty (cantFailMatchResult body)
+ ; fail_msg <- mkStringExpr (mk_fail_msg pat)
+ ; let fail_expr = mkApps (Var fail_id) [Type b_ty, fail_msg]
+ ; match_code <- extractMatchResult match fail_expr
+
+ ; rhs' <- dsLExpr rhs
+ ; returnDs (mkApps (Var bind_id) [Type (hsPatType pat), Type b_ty,
+ rhs', Lam var match_code]) }
+
+ go (RecStmt rec_stmts later_ids rec_ids rec_rets binds : stmts)
+ = ASSERT( length rec_ids > 0 )
+ ASSERT( length rec_ids == length rec_rets )
+ go (new_bind_stmt : let_stmt : stmts)
+ where
+ new_bind_stmt = mkBindStmt (mk_tup_pat later_pats) mfix_app
+ let_stmt = LetStmt (HsValBinds (ValBindsOut [(Recursive, binds)] []))
+
+
+ -- Remove the later_ids that appear (without fancy coercions)
+ -- in rec_rets, because there's no need to knot-tie them separately
+ -- See Note [RecStmt] in HsExpr
+ later_ids' = filter (`notElem` mono_rec_ids) later_ids
+ mono_rec_ids = [ id | HsVar id <- rec_rets ]
+
+ mfix_app = nlHsApp (noLoc $ TyApp (nlHsVar mfix_id) [tup_ty]) mfix_arg
+ mfix_arg = noLoc $ HsLam (MatchGroup [mkSimpleMatch [mfix_pat] body]
+ (mkFunTy tup_ty body_ty))
+
+ -- The rec_tup_pat must bind the rec_ids only; remember that the
+ -- trimmed_laters may share the same Names
+ -- Meanwhile, the later_pats must bind the later_vars
+ rec_tup_pats = map mk_wild_pat later_ids' ++ map nlVarPat rec_ids
+ later_pats = map nlVarPat later_ids' ++ map mk_later_pat rec_ids
+ rets = map nlHsVar later_ids' ++ map noLoc rec_rets
+
+ mfix_pat = noLoc $ LazyPat $ mk_tup_pat rec_tup_pats
+ body = noLoc $ HsDo ctxt rec_stmts return_app body_ty
+ body_ty = mkAppTy m_ty tup_ty
+ tup_ty = mkCoreTupTy (map idType (later_ids' ++ rec_ids))
+ -- mkCoreTupTy deals with singleton case
+
+ return_app = nlHsApp (noLoc $ TyApp (nlHsVar return_id) [tup_ty])
+ (mk_ret_tup rets)
+
+ mk_wild_pat :: Id -> LPat Id
+ mk_wild_pat v = noLoc $ WildPat $ idType v
+
+ mk_later_pat :: Id -> LPat Id
+ mk_later_pat v | v `elem` later_ids' = mk_wild_pat v
+ | otherwise = nlVarPat v
+
+ mk_tup_pat :: [LPat Id] -> LPat Id
+ mk_tup_pat [p] = p
+ mk_tup_pat ps = noLoc $ mkVanillaTuplePat ps Boxed
+
+ mk_ret_tup :: [LHsExpr Id] -> LHsExpr Id
+ mk_ret_tup [r] = r
+ mk_ret_tup rs = noLoc $ ExplicitTuple rs Boxed
\end{code}
projects / ghc-hetmet.git / blobdiff