+++ /dev/null
-%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
-%
-\section[Desugar]{@deSugar@: the main function}
-
-\begin{code}
-module Desugar ( deSugar, deSugarExpr ) where
-
-#include "HsVersions.h"
-
-import DynFlags ( DynFlag(..), DynFlags(..), dopt, GhcMode(..) )
-import StaticFlags ( opt_SccProfilingOn )
-import DriverPhases ( isHsBoot )
-import HscTypes ( ModGuts(..), HscEnv(..),
- Dependencies(..), ForeignStubs(..), TypeEnv, IsBootInterface )
-import HsSyn ( RuleDecl(..), RuleBndr(..), LHsExpr, LRuleDecl )
-import TcRnTypes ( TcGblEnv(..), ImportAvails(..) )
-import MkIface ( mkUsageInfo )
-import Id ( Id, setIdExported, idName )
-import Name ( Name, isExternalName, nameIsLocalOrFrom, nameOccName )
-import CoreSyn
-import PprCore ( pprRules, pprCoreExpr )
-import DsMonad
-import DsExpr ( dsLExpr )
-import DsBinds ( dsTopLHsBinds, decomposeRuleLhs, AutoScc(..) )
-import DsForeign ( dsForeigns )
-import DsExpr () -- Forces DsExpr to be compiled; DsBinds only
- -- depends on DsExpr.hi-boot.
-import Module ( Module, moduleEnvElts, delModuleEnv, moduleFS )
-import RdrName ( GlobalRdrEnv )
-import NameSet
-import VarSet
-import Bag ( Bag, isEmptyBag, emptyBag )
-import Rules ( roughTopNames )
-import CoreLint ( showPass, endPass )
-import CoreFVs ( ruleRhsFreeVars, exprsFreeNames )
-import Packages ( PackageState(thPackageId), PackageIdH(..) )
-import ErrUtils ( doIfSet, dumpIfSet_dyn, printBagOfWarnings,
- errorsFound, WarnMsg )
-import ListSetOps ( insertList )
-import Outputable
-import UniqSupply ( mkSplitUniqSupply )
-import SrcLoc ( Located(..) )
-import DATA_IOREF ( readIORef )
-import Maybes ( catMaybes )
-import FastString
-import Util ( sortLe )
-\end{code}
-
-%************************************************************************
-%* *
-%* The main function: deSugar
-%* *
-%************************************************************************
-
-\begin{code}
-deSugar :: HscEnv -> TcGblEnv -> IO (Bag WarnMsg, Maybe ModGuts)
--- Can modify PCS by faulting in more declarations
-
-deSugar hsc_env
- tcg_env@(TcGblEnv { tcg_mod = mod,
- tcg_src = hsc_src,
- tcg_type_env = type_env,
- tcg_imports = imports,
- tcg_home_mods = home_mods,
- tcg_exports = exports,
- tcg_dus = dus,
- tcg_inst_uses = dfun_uses_var,
- tcg_th_used = th_var,
- tcg_keep = keep_var,
- tcg_rdr_env = rdr_env,
- tcg_fix_env = fix_env,
- tcg_deprecs = deprecs,
- tcg_binds = binds,
- tcg_fords = fords,
- tcg_rules = rules,
- tcg_insts = insts })
- = do { showPass dflags "Desugar"
-
- -- Desugar the program
- ; ((all_prs, ds_rules, ds_fords), warns)
- <- case ghcMode (hsc_dflags hsc_env) of
- JustTypecheck -> return (([], [], NoStubs), emptyBag)
- _ -> initDs hsc_env mod rdr_env type_env $ do
- { core_prs <- dsTopLHsBinds auto_scc binds
- ; (ds_fords, foreign_prs) <- dsForeigns fords
- ; let all_prs = foreign_prs ++ core_prs
- local_bndrs = mkVarSet (map fst all_prs)
- ; ds_rules <- mappM (dsRule mod local_bndrs) rules
- ; return (all_prs, catMaybes ds_rules, ds_fords)
- }
-
- -- If warnings are considered errors, leave.
- ; if errorsFound dflags (warns, emptyBag)
- then return (warns, Nothing)
- else do
-
- { -- Add export flags to bindings
- keep_alive <- readIORef keep_var
- ; let final_prs = addExportFlags ghci_mode exports keep_alive
- all_prs ds_rules
- ds_binds = [Rec final_prs]
- -- Notice that we put the whole lot in a big Rec, even the foreign binds
- -- When compiling PrelFloat, which defines data Float = F# Float#
- -- we want F# to be in scope in the foreign marshalling code!
- -- You might think it doesn't matter, but the simplifier brings all top-level
- -- things into the in-scope set before simplifying; so we get no unfolding for F#!
-
- -- Lint result if necessary
- ; endPass dflags "Desugar" Opt_D_dump_ds ds_binds
-
- -- Dump output
- ; doIfSet (dopt Opt_D_dump_ds dflags)
- (printDump (ppr_ds_rules ds_rules))
-
- ; dfun_uses <- readIORef dfun_uses_var -- What dfuns are used
- ; th_used <- readIORef th_var -- Whether TH is used
- ; let used_names = allUses dus `unionNameSets` dfun_uses
- thPackage = thPackageId (pkgState dflags)
- pkgs | ExtPackage th_id <- thPackage, th_used
- = insertList th_id (imp_dep_pkgs imports)
- | otherwise
- = imp_dep_pkgs imports
-
- dep_mods = moduleEnvElts (delModuleEnv (imp_dep_mods imports) mod)
- -- M.hi-boot can be in the imp_dep_mods, but we must remove
- -- it before recording the modules on which this one depends!
- -- (We want to retain M.hi-boot in imp_dep_mods so that
- -- loadHiBootInterface can see if M's direct imports depend
- -- on M.hi-boot, and hence that we should do the hi-boot consistency
- -- check.)
-
- dir_imp_mods = imp_mods imports
-
- ; usages <- mkUsageInfo hsc_env home_mods dir_imp_mods dep_mods used_names
-
- ; let
- -- Modules don't compare lexicographically usually,
- -- but we want them to do so here.
- le_mod :: Module -> Module -> Bool
- le_mod m1 m2 = moduleFS m1 <= moduleFS m2
- le_dep_mod :: (Module, IsBootInterface) -> (Module, IsBootInterface) -> Bool
- le_dep_mod (m1,_) (m2,_) = m1 `le_mod` m2
-
- deps = Deps { dep_mods = sortLe le_dep_mod dep_mods,
- dep_pkgs = sortLe (<=) pkgs,
- dep_orphs = sortLe le_mod (imp_orphs imports) }
- -- sort to get into canonical order
-
- mod_guts = ModGuts {
- mg_module = mod,
- mg_boot = isHsBoot hsc_src,
- mg_exports = exports,
- mg_deps = deps,
- mg_home_mods = home_mods,
- mg_usages = usages,
- mg_dir_imps = [m | (m,_,_) <- moduleEnvElts dir_imp_mods],
- mg_rdr_env = rdr_env,
- mg_fix_env = fix_env,
- mg_deprecs = deprecs,
- mg_types = type_env,
- mg_insts = insts,
- mg_rules = ds_rules,
- mg_binds = ds_binds,
- mg_foreign = ds_fords }
-
- ; return (warns, Just mod_guts)
- }}
-
- where
- dflags = hsc_dflags hsc_env
- ghci_mode = ghcMode (hsc_dflags hsc_env)
- auto_scc | opt_SccProfilingOn = TopLevel
- | otherwise = NoSccs
-
-deSugarExpr :: HscEnv
- -> Module -> GlobalRdrEnv -> TypeEnv
- -> LHsExpr Id
- -> IO CoreExpr
-deSugarExpr hsc_env this_mod rdr_env type_env tc_expr
- = do { showPass dflags "Desugar"
- ; us <- mkSplitUniqSupply 'd'
-
- -- Do desugaring
- ; (core_expr, ds_warns) <- initDs hsc_env this_mod rdr_env type_env $
- dsLExpr tc_expr
-
- -- Display any warnings
- -- Note: if -Werror is used, we don't signal an error here.
- ; doIfSet (not (isEmptyBag ds_warns))
- (printBagOfWarnings dflags ds_warns)
-
- -- Dump output
- ; dumpIfSet_dyn dflags Opt_D_dump_ds "Desugared" (pprCoreExpr core_expr)
-
- ; return core_expr
- }
- where
- dflags = hsc_dflags hsc_env
-
-
--- addExportFlags
--- Set the no-discard flag if either
--- a) the Id is exported
--- b) it's mentioned in the RHS of an orphan rule
--- c) it's in the keep-alive set
---
--- It means that the binding won't be discarded EVEN if the binding
--- ends up being trivial (v = w) -- the simplifier would usually just
--- substitute w for v throughout, but we don't apply the substitution to
--- the rules (maybe we should?), so this substitution would make the rule
--- bogus.
-
--- You might wonder why exported Ids aren't already marked as such;
--- it's just because the type checker is rather busy already and
--- I didn't want to pass in yet another mapping.
-
-addExportFlags ghci_mode exports keep_alive prs rules
- = [(add_export bndr, rhs) | (bndr,rhs) <- prs]
- where
- add_export bndr
- | dont_discard bndr = setIdExported bndr
- | otherwise = bndr
-
- orph_rhs_fvs = unionVarSets [ ruleRhsFreeVars rule
- | rule <- rules,
- not (isLocalRule rule) ]
- -- A non-local rule keeps alive the free vars of its right-hand side.
- -- (A "non-local" is one whose head function is not locally defined.)
- -- Local rules are (later, after gentle simplification)
- -- attached to the Id, and that keeps the rhs free vars alive.
-
- dont_discard bndr = is_exported name
- || name `elemNameSet` keep_alive
- || bndr `elemVarSet` orph_rhs_fvs
- where
- name = idName bndr
-
- -- In interactive mode, we don't want to discard any top-level
- -- entities at all (eg. do not inline them away during
- -- simplification), and retain them all in the TypeEnv so they are
- -- available from the command line.
- --
- -- isExternalName separates the user-defined top-level names from those
- -- introduced by the type checker.
- is_exported :: Name -> Bool
- is_exported | ghci_mode == Interactive = isExternalName
- | otherwise = (`elemNameSet` exports)
-
-ppr_ds_rules [] = empty
-ppr_ds_rules rules
- = text "" $$ text "-------------- DESUGARED RULES -----------------" $$
- pprRules rules
-\end{code}
-
-
-
-%************************************************************************
-%* *
-%* Desugaring transformation rules
-%* *
-%************************************************************************
-
-\begin{code}
-dsRule :: Module -> IdSet -> LRuleDecl Id -> DsM (Maybe CoreRule)
-dsRule mod in_scope (L loc (HsRule name act vars lhs tv_lhs rhs fv_rhs))
- = putSrcSpanDs loc $
- do { let bndrs = [var | RuleBndr (L _ var) <- vars]
- ; lhs' <- dsLExpr lhs
- ; rhs' <- dsLExpr rhs
-
- ; case decomposeRuleLhs bndrs lhs' of {
- Nothing -> do { dsWarn msg; return Nothing } ;
- Just (bndrs', fn_id, args) -> do
-
- -- Substitute the dict bindings eagerly,
- -- and take the body apart into a (f args) form
- { let local_rule = nameIsLocalOrFrom mod fn_name
- -- NB we can't use isLocalId in the orphan test,
- -- because isLocalId isn't true of class methods
- fn_name = idName fn_id
- lhs_names = fn_name : nameSetToList (exprsFreeNames args)
- -- No need to delete bndrs, because
- -- exprsFreeNames finds only External names
- orph = case filter (nameIsLocalOrFrom mod) lhs_names of
- (n:ns) -> Just (nameOccName n)
- [] -> Nothing
-
- rule = Rule { ru_name = name, ru_fn = fn_name, ru_act = act,
- ru_bndrs = bndrs', ru_args = args, ru_rhs = rhs',
- ru_rough = roughTopNames args,
- ru_local = local_rule, ru_orph = orph }
- ; return (Just rule)
- } } }
- where
- msg = hang (ptext SLIT("RULE left-hand side too complicated to desugar; ignored"))
- 2 (ppr lhs)
-\end{code}
projects / ghc-hetmet.git / blobdiff