module DsExpr ( dsExpr, dsLExpr, dsLocalBinds, dsValBinds, dsLit ) where
#include "HsVersions.h"
import Match
import MatchLit
import DsBinds
import DsGRHSs
import DsListComp
import DsUtils
import DsArrows
import DsMonad
import Name
import NameEnv
import FamInstEnv( topNormaliseType )
#ifdef GHCI
import DsMeta
#endif
import HsSyn
import Platform
import TcType
import Coercion ( Role(..) )
import TcEvidence
import TcRnMonad
import Type
import CoreSyn
import CoreUtils
import CoreFVs
import MkCore
import DynFlags
import CostCentre
import Id
import Module
import VarSet
import VarEnv
import ConLike
import DataCon
import TysWiredIn
import PrelNames
import BasicTypes
import Maybes
import SrcLoc
import Util
import Bag
import Outputable
import FastString
import IdInfo
import Data.IORef ( atomicModifyIORef, modifyIORef )
import Control.Monad
import GHC.Fingerprint
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 = foldrM ds_val_bind body binds
dsValBinds (ValBindsIn _ _) _ = panic "dsValBinds ValBindsIn"
dsIPBinds :: HsIPBinds Id -> CoreExpr -> DsM CoreExpr
dsIPBinds (IPBinds ip_binds ev_binds) body
= do { ds_binds <- dsTcEvBinds ev_binds
; let inner = mkCoreLets ds_binds body
; foldrM ds_ip_bind inner ip_binds }
where
ds_ip_bind (L _ (IPBind ~(Right n) e)) body
= do e' <- dsLExpr e
return (Let (NonRec n e') body)
ds_val_bind :: (RecFlag, LHsBinds Id) -> CoreExpr -> DsM CoreExpr
ds_val_bind (NonRecursive, hsbinds) body
| [L loc bind] <- bagToList hsbinds,
strictMatchOnly bind
= putSrcSpanDs loc (dsStrictBind bind body)
ds_val_bind (_is_rec, binds) body
= do { prs <- dsLHsBinds binds
; ASSERT2( not (any (isUnLiftedType . idType . fst) prs), ppr _is_rec $$ ppr binds )
case prs of
[] -> return body
_ -> return (Let (Rec prs) body) }
dsStrictBind :: HsBind Id -> CoreExpr -> DsM CoreExpr
dsStrictBind (AbsBinds { abs_tvs = [], abs_ev_vars = []
, abs_exports = exports
, abs_ev_binds = ev_binds
, abs_binds = lbinds }) body
= do { let body1 = foldr bind_export body exports
bind_export export b = bindNonRec (abe_poly export) (Var (abe_mono export)) b
; body2 <- foldlBagM (\body lbind -> dsStrictBind (unLoc lbind) body)
body1 lbinds
; ds_binds <- dsTcEvBinds ev_binds
; return (mkCoreLets ds_binds body2) }
dsStrictBind (FunBind { fun_id = L _ fun, fun_matches = matches, fun_co_fn = co_fn
, fun_tick = tick, fun_infix = inf }) body
= do { (args, rhs) <- matchWrapper (FunRhs (idName fun ) inf) matches
; MASSERT( null args )
; MASSERT( isIdHsWrapper co_fn )
; let rhs' = mkOptTickBox tick rhs
; return (bindNonRec fun rhs' body) }
dsStrictBind (PatBind {pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty = ty }) body
=
do { rhs <- dsGuarded grhss ty
; let upat = unLoc pat
eqn = EqnInfo { eqn_pats = [upat],
eqn_rhs = cantFailMatchResult body }
; var <- selectMatchVar upat
; result <- matchEquations PatBindRhs [var] [eqn] (exprType body)
; return (bindNonRec var rhs result) }
dsStrictBind bind body = pprPanic "dsLet: unlifted" (ppr bind $$ ppr body)
strictMatchOnly :: HsBind Id -> Bool
strictMatchOnly (AbsBinds { abs_binds = lbinds })
= anyBag (strictMatchOnly . unLoc) lbinds
strictMatchOnly (PatBind { pat_lhs = lpat, pat_rhs_ty = rhs_ty })
= isUnLiftedType rhs_ty
|| isStrictLPat lpat
|| any (isUnLiftedType . idType) (collectPatBinders lpat)
strictMatchOnly (FunBind { fun_id = L _ id })
= isUnLiftedType (idType id)
strictMatchOnly _ = False
dsLExpr :: LHsExpr Id -> DsM CoreExpr
dsLExpr (L loc e) = putSrcSpanDs loc $ dsExpr e
dsExpr :: HsExpr Id -> DsM CoreExpr
dsExpr (HsPar e) = dsLExpr e
dsExpr (ExprWithTySigOut e _) = dsLExpr e
dsExpr (HsVar var) = return (varToCoreExpr var)
dsExpr (HsIPVar _) = panic "dsExpr: HsIPVar"
dsExpr (HsLit lit) = dsLit lit
dsExpr (HsOverLit lit) = dsOverLit lit
dsExpr (HsWrap co_fn e)
= do { e' <- dsExpr e
; wrapped_e <- dsHsWrapper co_fn e'
; dflags <- getDynFlags
; warnAboutIdentities dflags e' (exprType wrapped_e)
; return wrapped_e }
dsExpr (NegApp expr neg_expr)
= App <$> dsExpr neg_expr <*> dsLExpr expr
dsExpr (HsLam a_Match)
= uncurry mkLams <$> matchWrapper LambdaExpr a_Match
dsExpr (HsLamCase arg matches)
= do { arg_var <- newSysLocalDs arg
; ([discrim_var], matching_code) <- matchWrapper CaseAlt matches
; return $ Lam arg_var $ bindNonRec discrim_var (Var arg_var) matching_code }
dsExpr (HsApp fun arg)
= mkCoreAppDs <$> dsLExpr fun <*> dsLExpr arg
dsExpr (HsUnboundVar _) = panic "dsExpr: HsUnboundVar"
dsExpr (OpApp e1 op _ e2)
=
mkCoreAppsDs <$> dsLExpr op <*> mapM dsLExpr [e1, e2]
dsExpr (SectionL expr op)
= mkCoreAppDs <$> dsLExpr op <*> dsLExpr expr
dsExpr (SectionR op expr) = do
core_op <- dsLExpr op
let (x_ty:y_ty:_, _) = splitFunTys (exprType core_op)
y_core <- dsLExpr expr
x_id <- newSysLocalDs x_ty
y_id <- newSysLocalDs y_ty
return (bindNonRec y_id y_core $
Lam x_id (mkCoreAppsDs core_op [Var x_id, Var y_id]))
dsExpr (ExplicitTuple tup_args boxity)
= do { let go (lam_vars, args) (L _ (Missing ty))
= do { lam_var <- newSysLocalDs ty
; return (lam_var : lam_vars, Var lam_var : args) }
go (lam_vars, args) (L _ (Present expr))
= do { core_expr <- dsLExpr expr
; return (lam_vars, core_expr : args) }
; (lam_vars, args) <- foldM go ([], []) (reverse tup_args)
; return $ mkCoreLams lam_vars $
mkCoreConApps (tupleCon (boxityNormalTupleSort boxity) (length tup_args))
(map (Type . exprType) args ++ args) }
dsExpr (HsSCC cc expr@(L loc _)) = do
mod_name <- getModule
count <- goptM Opt_ProfCountEntries
uniq <- newUnique
Tick (ProfNote (mkUserCC cc mod_name loc uniq) count True) <$> dsLExpr expr
dsExpr (HsCoreAnn _ expr)
= dsLExpr expr
dsExpr (HsCase discrim matches)
= do { core_discrim <- dsLExpr discrim
; ([discrim_var], matching_code) <- matchWrapper CaseAlt matches
; return (bindNonRec discrim_var core_discrim matching_code) }
dsExpr (HsLet binds body) = do
body' <- dsLExpr body
dsLocalBinds binds body'
dsExpr (HsDo ListComp stmts res_ty) = dsListComp stmts res_ty
dsExpr (HsDo PArrComp stmts _) = dsPArrComp (map unLoc stmts)
dsExpr (HsDo DoExpr stmts _) = dsDo stmts
dsExpr (HsDo GhciStmtCtxt stmts _) = dsDo stmts
dsExpr (HsDo MDoExpr stmts _) = dsDo stmts
dsExpr (HsDo MonadComp stmts _) = dsMonadComp stmts
dsExpr (HsIf mb_fun guard_expr then_expr else_expr)
= do { pred <- dsLExpr guard_expr
; b1 <- dsLExpr then_expr
; b2 <- dsLExpr else_expr
; case mb_fun of
Just fun -> do { core_fun <- dsExpr fun
; return (mkCoreApps core_fun [pred,b1,b2]) }
Nothing -> return $ mkIfThenElse pred b1 b2 }
dsExpr (HsMultiIf res_ty alts)
| null alts
= mkErrorExpr
| otherwise
= do { match_result <- liftM (foldr1 combineMatchResults)
(mapM (dsGRHS IfAlt res_ty) alts)
; error_expr <- mkErrorExpr
; extractMatchResult match_result error_expr }
where
mkErrorExpr = mkErrorAppDs nON_EXHAUSTIVE_GUARDS_ERROR_ID res_ty
(ptext (sLit "multi-way if"))
dsExpr (ExplicitList elt_ty wit xs)
= dsExplicitList elt_ty wit xs
dsExpr (ExplicitPArr ty []) = do
emptyP <- dsDPHBuiltin emptyPVar
return (Var emptyP `App` Type ty)
dsExpr (ExplicitPArr ty xs) = do
singletonP <- dsDPHBuiltin singletonPVar
appP <- dsDPHBuiltin appPVar
xs' <- mapM dsLExpr xs
return . foldr1 (binary appP) $ map (unary singletonP) xs'
where
unary fn x = mkApps (Var fn) [Type ty, x]
binary fn x y = mkApps (Var fn) [Type ty, x, y]
dsExpr (ArithSeq expr witness seq)
= case witness of
Nothing -> dsArithSeq expr seq
Just fl -> do {
; fl' <- dsExpr fl
; newArithSeq <- dsArithSeq expr seq
; return (App fl' newArithSeq)}
dsExpr (PArrSeq expr (FromTo from to))
= mkApps <$> dsExpr expr <*> mapM dsLExpr [from, to]
dsExpr (PArrSeq expr (FromThenTo from thn to))
= mkApps <$> dsExpr expr <*> mapM dsLExpr [from, thn, to]
dsExpr (PArrSeq _ _)
= panic "DsExpr.dsExpr: Infinite parallel array!"
dsExpr (HsStatic expr@(L loc _)) = do
expr_ds <- dsLExpr expr
let ty = exprType expr_ds
n' <- mkSptEntryName loc
static_binds_var <- dsGetStaticBindsVar
staticPtrTyCon <- dsLookupTyCon staticPtrTyConName
staticPtrInfoDataCon <- dsLookupDataCon staticPtrInfoDataConName
staticPtrDataCon <- dsLookupDataCon staticPtrDataConName
fingerprintDataCon <- dsLookupDataCon fingerprintDataConName
dflags <- getDynFlags
let (line, col) = case loc of
RealSrcSpan r -> ( srcLocLine $ realSrcSpanStart r
, srcLocCol $ realSrcSpanStart r
)
_ -> (0, 0)
srcLoc = mkCoreConApps (tupleCon BoxedTuple 2)
[ Type intTy , Type intTy
, mkIntExprInt dflags line, mkIntExprInt dflags col
]
info <- mkConApp staticPtrInfoDataCon <$>
(++[srcLoc]) <$>
mapM mkStringExprFS
[ packageKeyFS $ modulePackageKey $ nameModule n'
, moduleNameFS $ moduleName $ nameModule n'
, occNameFS $ nameOccName n'
]
let tvars = varSetElems $ tyVarsOfType ty
speTy = mkForAllTys tvars $ mkTyConApp staticPtrTyCon [ty]
speId = mkExportedLocalId VanillaId n' speTy
fp@(Fingerprint w0 w1) = fingerprintName $ idName speId
fp_core = mkConApp fingerprintDataCon
[ mkWord64LitWordRep dflags w0
, mkWord64LitWordRep dflags w1
]
sp = mkConApp staticPtrDataCon [Type ty, fp_core, info, expr_ds]
liftIO $ modifyIORef static_binds_var ((fp, (speId, mkLams tvars sp)) :)
putSrcSpanDs loc $ return $ mkTyApps (Var speId) (map mkTyVarTy tvars)
where
mkWord64LitWordRep dflags
| platformWordSize (targetPlatform dflags) < 8 = mkWord64LitWord64
| otherwise = mkWordLit dflags . toInteger
fingerprintName :: Name -> Fingerprint
fingerprintName n = fingerprintString $ unpackFS $ concatFS
[ packageKeyFS $ modulePackageKey $ nameModule n
, fsLit ":"
, moduleNameFS (moduleName $ nameModule n)
, fsLit "."
, occNameFS $ occName n
]
dsExpr (RecordCon (L _ data_con_id) con_expr rbinds) = do
con_expr' <- dsExpr con_expr
let
(arg_tys, _) = tcSplitFunTys (exprType con_expr')
mk_arg (arg_ty, lbl)
= case findField (rec_flds rbinds) lbl of
(rhs:rhss) -> ASSERT( null rhss )
dsLExpr rhs
[] -> mkErrorAppDs rEC_CON_ERROR_ID arg_ty (ppr lbl)
unlabelled_bottom arg_ty = mkErrorAppDs rEC_CON_ERROR_ID arg_ty Outputable.empty
labels = dataConFieldLabels (idDataCon data_con_id)
con_args <- if null labels
then mapM unlabelled_bottom arg_tys
else mapM mk_arg (zipEqual "dsExpr:RecordCon" arg_tys labels)
return (mkCoreApps con_expr' con_args)
dsExpr expr@(RecordUpd record_expr (HsRecFields { rec_flds = fields })
cons_to_upd in_inst_tys out_inst_tys)
| null fields
= dsLExpr record_expr
| otherwise
= ASSERT2( notNull cons_to_upd, ppr expr )
do { record_expr' <- dsLExpr record_expr
; field_binds' <- mapM ds_field fields
; let upd_fld_env :: NameEnv Id
upd_fld_env = mkNameEnv [(f,l) | (f,l,_) <- field_binds']
; alts <- mapM (mk_alt upd_fld_env) cons_to_upd
; ([discrim_var], matching_code)
<- matchWrapper RecUpd (MG { mg_alts = alts, mg_arg_tys = [in_ty]
, mg_res_ty = out_ty, mg_origin = FromSource })
; return (add_field_binds field_binds' $
bindNonRec discrim_var record_expr' matching_code) }
where
ds_field :: LHsRecField Id (LHsExpr Id) -> DsM (Name, Id, CoreExpr)
ds_field (L _ rec_field) = do { rhs <- dsLExpr (hsRecFieldArg rec_field)
; let fld_id = unLoc (hsRecFieldId rec_field)
; lcl_id <- newSysLocalDs (idType fld_id)
; return (idName fld_id, lcl_id, rhs) }
add_field_binds [] expr = expr
add_field_binds ((_,b,r):bs) expr = bindNonRec b r (add_field_binds bs expr)
tycon = dataConTyCon (head cons_to_upd)
in_ty = mkTyConApp tycon in_inst_tys
out_ty = mkFamilyTyConApp tycon out_inst_tys
mk_alt upd_fld_env con
= do { let (univ_tvs, ex_tvs, eq_spec,
theta, arg_tys, _) = dataConFullSig con
subst = mkTopTvSubst (univ_tvs `zip` in_inst_tys)
; eqs_vars <- mapM newPredVarDs (substTheta subst (eqSpecPreds eq_spec))
; theta_vars <- mapM newPredVarDs (substTheta subst theta)
; arg_ids <- newSysLocalsDs (substTys subst arg_tys)
; let val_args = zipWithEqual "dsExpr:RecordUpd" mk_val_arg
(dataConFieldLabels con) arg_ids
mk_val_arg field_name pat_arg_id
= nlHsVar (lookupNameEnv upd_fld_env field_name `orElse` pat_arg_id)
inst_con = noLoc $ HsWrap wrap (HsVar (dataConWrapId con))
wrap = mkWpEvVarApps theta_vars <.>
mkWpTyApps (mkTyVarTys ex_tvs) <.>
mkWpTyApps [ty | (tv, ty) <- univ_tvs `zip` out_inst_tys
, not (tv `elemVarEnv` wrap_subst) ]
rhs = foldl (\a b -> nlHsApp a b) inst_con val_args
wrap_co = mkTcTyConAppCo Nominal tycon
[ lookup tv ty | (tv,ty) <- univ_tvs `zip` out_inst_tys ]
lookup univ_tv ty = case lookupVarEnv wrap_subst univ_tv of
Just co' -> co'
Nothing -> mkTcReflCo Nominal ty
wrap_subst = mkVarEnv [ (tv, mkTcSymCo (mkTcCoVarCo eq_var))
| ((tv,_),eq_var) <- eq_spec `zip` eqs_vars ]
pat = noLoc $ ConPatOut { pat_con = noLoc (RealDataCon con)
, pat_tvs = ex_tvs
, pat_dicts = eqs_vars ++ theta_vars
, pat_binds = emptyTcEvBinds
, pat_args = PrefixCon $ map nlVarPat arg_ids
, pat_arg_tys = in_inst_tys
, pat_wrap = idHsWrapper }
; let wrapped_rhs | null eq_spec = rhs
| otherwise = mkLHsWrap (mkWpCast (mkTcSubCo wrap_co)) rhs
; return (mkSimpleMatch [pat] wrapped_rhs) }
dsExpr (HsRnBracketOut _ _) = panic "dsExpr HsRnBracketOut"
#ifdef GHCI
dsExpr (HsTcBracketOut x ps) = dsBracket x ps
#else
dsExpr (HsTcBracketOut _ _) = panic "dsExpr HsBracketOut"
#endif
dsExpr (HsSpliceE _ s) = pprPanic "dsExpr:splice" (ppr s)
dsExpr (HsProc pat cmd) = dsProcExpr pat cmd
dsExpr (HsTick tickish e) = do
e' <- dsLExpr e
return (Tick tickish e')
dsExpr (HsBinTick ixT ixF e) = do
e2 <- dsLExpr e
do { ASSERT(exprType e2 `eqType` boolTy)
mkBinaryTickBox ixT ixF e2
}
dsExpr (ExprWithTySig {}) = panic "dsExpr:ExprWithTySig"
dsExpr (HsBracket {}) = panic "dsExpr:HsBracket"
dsExpr (HsQuasiQuoteE {}) = panic "dsExpr:HsQuasiQuoteE"
dsExpr (HsArrApp {}) = panic "dsExpr:HsArrApp"
dsExpr (HsArrForm {}) = panic "dsExpr:HsArrForm"
dsExpr (HsTickPragma {}) = panic "dsExpr:HsTickPragma"
dsExpr (EWildPat {}) = panic "dsExpr:EWildPat"
dsExpr (EAsPat {}) = panic "dsExpr:EAsPat"
dsExpr (EViewPat {}) = panic "dsExpr:EViewPat"
dsExpr (ELazyPat {}) = panic "dsExpr:ELazyPat"
dsExpr (HsType {}) = panic "dsExpr:HsType"
dsExpr (HsDo {}) = panic "dsExpr:HsDo"
findField :: [LHsRecField Id arg] -> Name -> [arg]
findField rbinds lbl
= [rhs | L _ (HsRecField { hsRecFieldId = id, hsRecFieldArg = rhs }) <- rbinds
, lbl == idName (unLoc id) ]
dsExplicitList :: PostTc Id Type -> Maybe (SyntaxExpr Id) -> [LHsExpr Id]
-> DsM CoreExpr
dsExplicitList elt_ty Nothing xs
= do { dflags <- getDynFlags
; xs' <- mapM dsLExpr xs
; let (dynamic_prefix, static_suffix) = spanTail is_static xs'
; if gopt Opt_SimpleListLiterals dflags
|| not (gopt Opt_EnableRewriteRules dflags)
|| null dynamic_prefix
then return $ mkListExpr elt_ty xs'
else mkBuildExpr elt_ty (mkSplitExplicitList dynamic_prefix static_suffix) }
where
is_static :: CoreExpr -> Bool
is_static e = all is_static_var (varSetElems (exprFreeVars e))
is_static_var :: Var -> Bool
is_static_var v
| isId v = isExternalName (idName v)
| otherwise = False
mkSplitExplicitList prefix suffix (c, _) (n, n_ty)
= do { let suffix' = mkListExpr elt_ty suffix
; folded_suffix <- mkFoldrExpr elt_ty n_ty (Var c) (Var n) suffix'
; return (foldr (App . App (Var c)) folded_suffix prefix) }
dsExplicitList elt_ty (Just fln) xs
= do { fln' <- dsExpr fln
; list <- dsExplicitList elt_ty Nothing xs
; dflags <- getDynFlags
; return (App (App fln' (mkIntExprInt dflags (length xs))) list) }
spanTail :: (a -> Bool) -> [a] -> ([a], [a])
spanTail f xs = (reverse rejected, reverse satisfying)
where (satisfying, rejected) = span f $ reverse xs
dsArithSeq :: PostTcExpr -> (ArithSeqInfo Id) -> DsM CoreExpr
dsArithSeq expr (From from)
= App <$> dsExpr expr <*> dsLExpr from
dsArithSeq expr (FromTo from to)
= do dflags <- getDynFlags
warnAboutEmptyEnumerations dflags from Nothing to
expr' <- dsExpr expr
from' <- dsLExpr from
to' <- dsLExpr to
return $ mkApps expr' [from', to']
dsArithSeq expr (FromThen from thn)
= mkApps <$> dsExpr expr <*> mapM dsLExpr [from, thn]
dsArithSeq expr (FromThenTo from thn to)
= do dflags <- getDynFlags
warnAboutEmptyEnumerations dflags from (Just thn) to
expr' <- dsExpr expr
from' <- dsLExpr from
thn' <- dsLExpr thn
to' <- dsLExpr to
return $ mkApps expr' [from', thn', to']
dsDo :: [ExprLStmt Id] -> DsM CoreExpr
dsDo stmts
= goL stmts
where
goL [] = panic "dsDo"
goL (L loc stmt:lstmts) = putSrcSpanDs loc (go loc stmt lstmts)
go _ (LastStmt body _) stmts
= ASSERT( null stmts ) dsLExpr body
go _ (BodyStmt rhs then_expr _ _) stmts
= do { rhs2 <- dsLExpr rhs
; warnDiscardedDoBindings rhs (exprType rhs2)
; then_expr2 <- dsExpr then_expr
; rest <- goL stmts
; return (mkApps then_expr2 [rhs2, rest]) }
go _ (LetStmt binds) stmts
= do { rest <- goL stmts
; dsLocalBinds binds rest }
go _ (BindStmt pat rhs bind_op fail_op) stmts
= do { body <- goL stmts
; rhs' <- dsLExpr rhs
; bind_op' <- dsExpr bind_op
; var <- selectSimpleMatchVarL pat
; let bind_ty = exprType bind_op'
res1_ty = funResultTy (funArgTy (funResultTy bind_ty))
; match <- matchSinglePat (Var var) (StmtCtxt DoExpr) pat
res1_ty (cantFailMatchResult body)
; match_code <- handle_failure pat match fail_op
; return (mkApps bind_op' [rhs', Lam var match_code]) }
go loc (RecStmt { recS_stmts = rec_stmts, recS_later_ids = later_ids
, recS_rec_ids = rec_ids, recS_ret_fn = return_op
, recS_mfix_fn = mfix_op, recS_bind_fn = bind_op
, recS_rec_rets = rec_rets, recS_ret_ty = body_ty }) stmts
= goL (new_bind_stmt : stmts)
where
new_bind_stmt = L loc $ BindStmt (mkBigLHsPatTup later_pats)
mfix_app bind_op
noSyntaxExpr
tup_ids = rec_ids ++ filterOut (`elem` rec_ids) later_ids
tup_ty = mkBigCoreTupTy (map idType tup_ids)
rec_tup_pats = map nlVarPat tup_ids
later_pats = rec_tup_pats
rets = map noLoc rec_rets
mfix_app = nlHsApp (noLoc mfix_op) mfix_arg
mfix_arg = noLoc $ HsLam (MG { mg_alts = [mkSimpleMatch [mfix_pat] body]
, mg_arg_tys = [tup_ty], mg_res_ty = body_ty
, mg_origin = Generated })
mfix_pat = noLoc $ LazyPat $ mkBigLHsPatTup rec_tup_pats
body = noLoc $ HsDo DoExpr (rec_stmts ++ [ret_stmt]) body_ty
ret_app = nlHsApp (noLoc return_op) (mkBigLHsTup rets)
ret_stmt = noLoc $ mkLastStmt ret_app
go _ (ParStmt {}) _ = panic "dsDo ParStmt"
go _ (TransStmt {}) _ = panic "dsDo TransStmt"
handle_failure :: LPat Id -> MatchResult -> SyntaxExpr Id -> DsM CoreExpr
handle_failure pat match fail_op
| matchCanFail match
= do { fail_op' <- dsExpr fail_op
; dflags <- getDynFlags
; fail_msg <- mkStringExpr (mk_fail_msg dflags pat)
; extractMatchResult match (App fail_op' fail_msg) }
| otherwise
= extractMatchResult match (error "It can't fail")
mk_fail_msg :: DynFlags -> Located e -> String
mk_fail_msg dflags pat = "Pattern match failure in do expression at " ++
showPpr dflags (getLoc pat)
warnDiscardedDoBindings :: LHsExpr Id -> Type -> DsM ()
warnDiscardedDoBindings rhs rhs_ty
| Just (m_ty, elt_ty) <- tcSplitAppTy_maybe rhs_ty
= do { warn_unused <- woptM Opt_WarnUnusedDoBind
; warn_wrong <- woptM Opt_WarnWrongDoBind
; when (warn_unused || warn_wrong) $
do { fam_inst_envs <- dsGetFamInstEnvs
; let norm_elt_ty = topNormaliseType fam_inst_envs elt_ty
; if warn_unused && not (isUnitTy norm_elt_ty)
then warnDs (badMonadBind rhs elt_ty
(ptext (sLit "-fno-warn-unused-do-bind")))
else
when warn_wrong $
do { case tcSplitAppTy_maybe norm_elt_ty of
Just (elt_m_ty, _)
| m_ty `eqType` topNormaliseType fam_inst_envs elt_m_ty
-> warnDs (badMonadBind rhs elt_ty
(ptext (sLit "-fno-warn-wrong-do-bind")))
_ -> return () } } }
| otherwise
= return ()
badMonadBind :: LHsExpr Id -> Type -> SDoc -> SDoc
badMonadBind rhs elt_ty flag_doc
= vcat [ hang (ptext (sLit "A do-notation statement discarded a result of type"))
2 (quotes (ppr elt_ty))
, hang (ptext (sLit "Suppress this warning by saying"))
2 (quotes $ ptext (sLit "_ <-") <+> ppr rhs)
, ptext (sLit "or by using the flag") <+> flag_doc ]
mkSptEntryName :: SrcSpan -> DsM Name
mkSptEntryName loc = do
uniq <- newUnique
mod <- getModule
occ <- mkWrapperName "sptEntry"
return $ mkExternalName uniq mod occ loc
where
mkWrapperName what
= do dflags <- getDynFlags
thisMod <- getModule
let
wrapperRef = nextWrapperNum dflags
wrapperNum <- liftIO $ atomicModifyIORef wrapperRef $ \mod_env ->
let num = lookupWithDefaultModuleEnv mod_env 0 thisMod
in (extendModuleEnv mod_env thisMod (num+1), num)
return $ mkVarOcc $ what ++ ":" ++ show wrapperNum