import DsMonad -- the monadery used in the desugarer
import DsUtils
-import CmdLineOpts ( opt_FoldrBuildOn )
+import CmdLineOpts ( opt_IgnoreIfacePragmas, opt_RulesOff )
import CoreUtils ( exprType, mkIfThenElse )
import Id ( idType )
import Var ( Id )
splitTyConApp_maybe )
import TysPrim ( alphaTyVar )
import TysWiredIn ( nilDataCon, consDataCon, trueDataConId, falseDataConId,
- unitDataConId, unitTy,
- mkListTy, mkTupleTy )
+ unitDataConId, unitTy, mkListTy )
import Match ( matchSimply )
import PrelNames ( foldrName, buildName, replicatePName, mapPName,
filterPName, zipPName, crossPName, parrTyConName )
-> DsM CoreExpr
dsListComp quals elt_ty
- | not opt_FoldrBuildOn -- Be boring
- || isParallelComp quals
+ | opt_RulesOff || opt_IgnoreIfacePragmas -- Either rules are switched off, or
+ -- we are ignoring what there are;
+ -- Either way foldr/build won't happen, so
+ -- use the more efficient Wadler-style desugaring
+ || isParallelComp quals -- Foldr-style desugaring can't handle
+ -- parallel list comprehensions
= deListComp quals (mkNilExpr elt_ty)
- | otherwise -- foldr/build lives!
+ | otherwise -- Foldr/build should be enabled, so desugar
+ -- into foldrs and builds
= newTyVarsDs [alphaTyVar] `thenDs` \ [n_tyvar] ->
let
n_ty = mkTyVarTy n_tyvar
returnDs (Var build_id `App` Type elt_ty
`App` mkLams [n_tyvar, c, n] result)
- where isParallelComp (ParStmtOut bndrstmtss : _) = True
- isParallelComp _ = False
+ where isParallelComp (ParStmt bndrstmtss : _) = True
+ isParallelComp _ = False
\end{code}
%************************************************************************
where (x1, .., xn) are the variables bound in p1, v1, p2
(y1, .., ym) are the variables bound in q1, v2, q2
-In the translation below, the ParStmtOut branch translates each parallel branch
+In the translation below, the ParStmt branch translates each parallel branch
into a sub-comprehension, and desugars each independently. The resulting lists
are fed to a zip function, we create a binding for all the variables bound in all
the comprehensions, and then we hand things off the the desugarer for bindings.
deListComp :: [TypecheckedStmt] -> CoreExpr -> DsM CoreExpr
-deListComp (ParStmtOut bndrstmtss : quals) list
- = mapDs do_list_comp bndrstmtss `thenDs` \ exps ->
+deListComp (ParStmt stmtss_w_bndrs : quals) list
+ = mapDs do_list_comp stmtss_w_bndrs `thenDs` \ exps ->
mkZipBind qual_tys `thenDs` \ (zip_fn, zip_rhs) ->
-- Deal with [e | pat <- zip l1 .. ln] in example above
deBindComp pat (Let (Rec [(zip_fn, zip_rhs)]) (mkApps (Var zip_fn) exps))
quals list
- where -- pat is the pattern ((x1,..,xn), (y1,..,ym)) in the example above
- pat = TuplePat pats Boxed
- pats = map (\(bs,_) -> mk_hs_tuple_pat bs) bndrstmtss
+ where
+ bndrs_s = map snd stmtss_w_bndrs
+
+ -- pat is the pattern ((x1,..,xn), (y1,..,ym)) in the example above
+ pat = TuplePat pats Boxed
+ pats = map mk_hs_tuple_pat bndrs_s
-- Types of (x1,..,xn), (y1,..,yn) etc
- qual_tys = [ mk_bndrs_tys bndrs | (bndrs,_) <- bndrstmtss ]
+ qual_tys = map mk_bndrs_tys bndrs_s
- do_list_comp (bndrs, stmts)
+ do_list_comp (stmts, bndrs)
= dsListComp (stmts ++ [ResultStmt (mk_hs_tuple_expr bndrs) noSrcLoc])
(mk_bndrs_tys bndrs)
- mk_bndrs_tys bndrs = mk_tuple_ty (map idType bndrs)
+ mk_bndrs_tys bndrs = mkCoreTupTy (map idType bndrs)
-- Last: the one to return
deListComp [ResultStmt expr locn] list -- Figure 7.4, SLPJ, p 135, rule C above
mapDs newSysLocalDs list_tys `thenDs` \ as's ->
newSysLocalDs zip_fn_ty `thenDs` \ zip_fn ->
let
- inner_rhs = mkConsExpr ret_elt_ty (mkTupleExpr as') (mkVarApps (Var zip_fn) as's)
+ inner_rhs = mkConsExpr ret_elt_ty
+ (mkCoreTup (map Var as'))
+ (mkVarApps (Var zip_fn) as's)
zip_body = foldr mk_case inner_rhs (zip3 ass as' as's)
in
returnDs (zip_fn, mkLams ass zip_body)
where
list_tys = map mkListTy elt_tys
- ret_elt_ty = mk_tuple_ty elt_tys
+ ret_elt_ty = mkCoreTupTy elt_tys
zip_fn_ty = mkFunTys list_tys (mkListTy ret_elt_ty)
mk_case (as, a', as') rest
= Case (Var as) as [(DataAlt nilDataCon, [], mkNilExpr ret_elt_ty),
(DataAlt consDataCon, [a', as'], rest)]
--- Helper function
-mk_tuple_ty :: [Type] -> Type
-mk_tuple_ty [ty] = ty
-mk_tuple_ty tys = mkTupleTy Boxed (length tys) tys
-
-- Helper functions that makes an HsTuple only for non-1-sized tuples
mk_hs_tuple_expr :: [Id] -> TypecheckedHsExpr
mk_hs_tuple_expr [] = HsVar unitDataConId
dsLookupGlobalId replicatePName `thenDs` \repP ->
let unitArray = mkApps (Var repP) [Type unitTy,
mkIntExpr 1,
- mkTupleExpr []]
+ mkCoreTup []]
in
dePArrComp qs (TuplePat [] Boxed) unitArray
ty'cea = parrElemType cea
in
newSysLocalDs ty'cea `thenDs` \v ->
- dsLet ds (mkTupleExpr xs) `thenDs` \clet ->
+ dsLet ds (mkCoreTup (map Var xs)) `thenDs` \clet ->
newSysLocalDs (exprType clet) `thenDs` \let'v ->
- let projBody = mkDsLet (NonRec let'v clet) $ mkTupleExpr [v, let'v]
+ let projBody = mkDsLet (NonRec let'v clet) $
+ mkCoreTup [Var v, Var let'v]
errTy = exprType projBody
errMsg = "DsListComp.dePArrComp: internal error!"
in
-- where
-- {x_1, ..., x_n} = DV (qs)
--
-dePArrComp (ParStmtOut [] : qss2) pa cea = dePArrComp qss2 pa cea
-dePArrComp (ParStmtOut ((xs, qs):qss) : qss2) pa cea =
+dePArrComp (ParStmt [] : qss2) pa cea = dePArrComp qss2 pa cea
+dePArrComp (ParStmt ((qs, xs):qss) : qss2) pa cea =
dsLookupGlobalId zipPName `thenDs` \zipP ->
let pa' = TuplePat [pa, TuplePat (map VarPat xs) Boxed] Boxed
ty'cea = parrElemType cea
let ty'cqs = parrElemType cqs
cea' = mkApps (Var zipP) [Type ty'cea, Type ty'cqs, cea, cqs]
in
- dePArrComp (ParStmtOut qss : qss2) pa' cea'
+ dePArrComp (ParStmt qss : qss2) pa' cea'
-- generate Core corresponding to `\p -> e'
--
projects / ghc-hetmet.git / blobdiff