\section[Desugar]{@deSugar@: the main function}
\begin{code}
-module Desugar ( deSugar ) where
+module Desugar ( deSugar, deSugarExpr ) where
#include "HsVersions.h"
-import CmdLineOpts ( opt_D_dump_ds )
-import HsSyn ( MonoBinds )
-import TcHsSyn ( TypecheckedMonoBinds, TypecheckedForeignDecl )
+import CmdLineOpts ( DynFlag(..), dopt, opt_SccProfilingOn )
+import HscTypes ( ModGuts(..), ModGuts, HscEnv(..), ExternalPackageState(..),
+ PersistentCompilerState(..), Dependencies(..), TypeEnv, GlobalRdrEnv,
+ lookupType, unQualInScope )
+import HsSyn ( MonoBinds, RuleDecl(..), RuleBndr(..),
+ HsExpr(..), HsBinds(..), MonoBinds(..) )
+import TcHsSyn ( TypecheckedRuleDecl, TypecheckedHsExpr )
+import TcRnTypes ( TcGblEnv(..), ImportAvails(..) )
+import MkIface ( mkUsageInfo )
+import Id ( Id )
import CoreSyn
+import PprCore ( pprIdRules, pprCoreExpr )
+import Subst ( substExpr, mkSubst, mkInScopeSet )
import DsMonad
+import DsExpr ( dsExpr )
import DsBinds ( dsMonoBinds, AutoScc(..) )
import DsForeign ( dsForeigns )
-import DsUtils
import DsExpr () -- Forces DsExpr to be compiled; DsBinds only
-- depends on DsExpr.hi-boot.
-import Module ( Module, moduleString )
-import Bag ( isEmptyBag, unionBags )
-import CmdLineOpts ( opt_SccGroup, opt_SccProfilingOn )
-import CoreLint ( beginPass, endPass )
-import ErrUtils ( doIfSet, pprBagOfWarnings )
+import Module ( Module, moduleEnvElts )
+import Id ( Id )
+import NameEnv ( lookupNameEnv )
+import VarEnv
+import VarSet
+import Bag ( isEmptyBag, mapBag )
+import CoreLint ( showPass, endPass )
+import ErrUtils ( doIfSet, dumpIfSet_dyn, pprBagOfWarnings, addShortWarnLocLine )
import Outputable
-import UniqSupply ( splitUniqSupply, UniqSupply )
+import qualified Pretty
+import UniqSupply ( mkSplitUniqSupply )
+import Maybes ( orElse )
+import SrcLoc ( SrcLoc )
+import FastString
+import DATA_IOREF ( readIORef )
\end{code}
-The only trick here is to get the @DsMonad@ stuff off to a good
-start.
+%************************************************************************
+%* *
+%* The main function: deSugar
+%* *
+%************************************************************************
\begin{code}
-deSugar :: UniqSupply -- name supply
- -> ValueEnv -- value env
- -> Module -- module name
- -> TypecheckedMonoBinds
- -> [TypecheckedForeignDecl]
- -> IO ([CoreBind], SDoc, SDoc) -- output
-
-deSugar us global_val_env mod_name all_binds fo_decls = do
- beginPass "Desugar"
+deSugar :: HscEnv -> PersistentCompilerState
+ -> TcGblEnv -> IO ModGuts
+
+deSugar hsc_env pcs
+ (TcGblEnv { tcg_mod = mod,
+ tcg_type_env = type_env,
+ tcg_usages = usage_var,
+ tcg_imports = imports,
+ tcg_exports = exports,
+ tcg_rdr_env = rdr_env,
+ tcg_fix_env = fix_env,
+ tcg_deprecs = deprecs,
+ tcg_insts = insts,
+ tcg_binds = binds,
+ tcg_fords = fords,
+ tcg_rules = rules })
+ = do { showPass dflags "Desugar"
+ ; us <- mkSplitUniqSupply 'd'
+ ; usages <- readIORef usage_var
+
-- Do desugaring
- let (core_prs, ds_warns1) = initDs us1 global_val_env module_and_group
- (dsMonoBinds auto_scc all_binds [])
- auto_scc | opt_SccProfilingOn = TopLevel
- | otherwise = NoSccs
- ds_binds' = [Rec core_prs]
+ ; let ((ds_binds, ds_rules, ds_fords), ds_warns)
+ = initDs dflags us lookup mod
+ (dsProgram binds rules fords)
+
+ warn_doc = pprBagOfWarnings (mapBag mk_warn ds_warns)
+
+ -- Display any warnings
+ ; doIfSet (not (isEmptyBag ds_warns))
+ (printErrs warn_doc)
+
+ -- 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))
+
+ ; let
+ deps = Deps { dep_mods = moduleEnvElts (imp_dep_mods imports),
+ dep_pkgs = imp_dep_pkgs imports,
+ dep_orphs = imp_orphs imports }
+ mod_guts = ModGuts {
+ mg_module = mod,
+ mg_exports = exports,
+ mg_deps = deps,
+ mg_usages = mkUsageInfo hsc_env eps imports usages,
+ mg_dir_imps = [m | (m,_) <- moduleEnvElts (imp_mods imports)],
+ 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 mod_guts
+ }
+
+ where
+ dflags = hsc_dflags hsc_env
+ print_unqual = unQualInScope rdr_env
+
+ -- Desugarer warnings are SDocs; here we
+ -- add the info about whether or not to print unqualified
+ mk_warn :: (SrcLoc,SDoc) -> (SrcLoc, Pretty.Doc)
+ mk_warn (loc, sdoc) = addShortWarnLocLine loc print_unqual sdoc
- ((fi_binds, fe_binds, h_code, c_code), ds_warns2) =
- initDs us3 global_val_env module_and_group (dsForeigns mod_name fo_decls)
+ -- The lookup function passed to initDs is used for well-known Ids,
+ -- such as fold, build, cons etc, so the chances are
+ -- it'll be found in the package symbol table. That's
+ -- why we don't merge all these tables
+ eps = pcs_EPS pcs
+ pte = eps_PTE eps
+ hpt = hsc_HPT hsc_env
+ lookup n = case lookupType hpt pte n of {
+ Just v -> v ;
+ other ->
+ case lookupNameEnv type_env n of
+ Just v -> v ;
+ other -> pprPanic "Desugar: lookup:" (ppr n)
+ }
- ds_binds = fi_binds ++ ds_binds' ++ fe_binds
+deSugarExpr :: HscEnv
+ -> PersistentCompilerState
+ -> Module -> GlobalRdrEnv -> TypeEnv
+ -> TypecheckedHsExpr
+ -> IO CoreExpr
+deSugarExpr hsc_env pcs this_mod rdr_env type_env tc_expr
+ = do { showPass dflags "Desugar"
+ ; us <- mkSplitUniqSupply 'd'
+
+ -- Do desugaring
+ ; let (core_expr, ds_warns) = initDs dflags us lookup this_mod (dsExpr tc_expr)
+ warn_doc = pprBagOfWarnings (mapBag mk_warn ds_warns)
- ds_warns = ds_warns1 `unionBags` ds_warns2
+ -- Display any warnings
+ ; doIfSet (not (isEmptyBag ds_warns))
+ (printErrs warn_doc)
- -- Display any warnings
- doIfSet (not (isEmptyBag ds_warns))
- (printErrs (pprBagOfWarnings ds_warns))
+ -- Dump output
+ ; dumpIfSet_dyn dflags Opt_D_dump_ds "Desugared" (pprCoreExpr core_expr)
- -- Lint result if necessary
- endPass "Desugar" opt_D_dump_ds ds_binds
- return (ds_binds, h_code, c_code)
+ ; return core_expr
+ }
where
- (us1, us2) = splitUniqSupply us
- (us3, us4) = splitUniqSupply us2
+ dflags = hsc_dflags hsc_env
+ hpt = hsc_HPT hsc_env
+ pte = eps_PTE (pcs_EPS pcs)
+ lookup n = pprTrace "lookup" (ppr type_env) (
+ lookupNameEnv type_env n `orElse` -- Look in the type env of the
+ -- current module first
+ lookupType hpt pte n `orElse` -- Then other modules
+ pprPanic "Desugar: lookup:" (ppr n)
+ )
+
+ mk_warn :: (SrcLoc,SDoc) -> (SrcLoc, Pretty.Doc)
+ mk_warn (loc,sdoc) = addShortWarnLocLine loc print_unqual sdoc
+
+ print_unqual = unQualInScope rdr_env
+
+dsProgram all_binds rules fo_decls
+ = dsMonoBinds auto_scc all_binds [] `thenDs` \ core_prs ->
+ dsForeigns fo_decls `thenDs` \ (ds_fords, foreign_binds) ->
+ let
+ ds_binds = [Rec (foreign_binds ++ core_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#!
+
+ local_binders = mkVarSet (bindersOfBinds ds_binds)
+ in
+ mapDs (dsRule local_binders) rules `thenDs` \ ds_rules ->
+ returnDs (ds_binds, ds_rules, ds_fords)
+ where
+ auto_scc | opt_SccProfilingOn = TopLevel
+ | otherwise = NoSccs
+
+ppr_ds_rules [] = empty
+ppr_ds_rules rules
+ = text "" $$ text "-------------- DESUGARED RULES -----------------" $$
+ pprIdRules rules
+\end{code}
+
+
+
+%************************************************************************
+%* *
+%* Desugaring transformation rules
+%* *
+%************************************************************************
+
+\begin{code}
+dsRule :: IdSet -> TypecheckedRuleDecl -> DsM (Id, CoreRule)
+dsRule in_scope (IfaceRuleOut fun rule) -- Built-in rules come this way
+ = returnDs (fun, rule)
+
+dsRule in_scope (HsRule name act vars lhs rhs loc)
+ = putSrcLocDs loc $
+ ds_lhs all_vars lhs `thenDs` \ (fn, args) ->
+ dsExpr rhs `thenDs` \ core_rhs ->
+ returnDs (fn, Rule name act tpl_vars args core_rhs)
+ where
+ tpl_vars = [var | RuleBndr var <- vars]
+ all_vars = mkInScopeSet (in_scope `unionVarSet` mkVarSet tpl_vars)
+
+ds_lhs all_vars lhs
+ = let
+ (dict_binds, body) = case lhs of
+ (HsLet (MonoBind dict_binds _ _) body) -> (dict_binds, body)
+ other -> (EmptyMonoBinds, lhs)
+ in
+ ds_dict_binds dict_binds `thenDs` \ dict_binds' ->
+ dsExpr body `thenDs` \ body' ->
+
+ -- Substitute the dict bindings eagerly,
+ -- and take the body apart into a (f args) form
+ let
+ subst_env = mkSubstEnv [id | (id,rhs) <- dict_binds']
+ [ContEx subst_env rhs | (id,rhs) <- dict_binds']
+ -- Note recursion here... substitution won't terminate
+ -- if there is genuine recursion... which there isn't
- module_and_group = (mod_name, grp_name)
- grp_name = case opt_SccGroup of
- Just xx -> _PK_ xx
- Nothing -> _PK_ (moduleString mod_name) -- default: module name
+ subst = mkSubst all_vars subst_env
+ body'' = substExpr subst body'
+ in
+
+ -- Now unpack the resulting body
+ let
+ pair = case collectArgs body'' of
+ (Var fn, args) -> (fn, args)
+ other -> pprPanic "dsRule" (ppr lhs)
+ in
+ returnDs pair
+ds_dict_binds EmptyMonoBinds = returnDs []
+ds_dict_binds (AndMonoBinds b1 b2) = ds_dict_binds b1 `thenDs` \ env1 ->
+ ds_dict_binds b2 `thenDs` \ env2 ->
+ returnDs (env1 ++ env2)
+ds_dict_binds (VarMonoBind id rhs) = dsExpr rhs `thenDs` \ rhs' ->
+ returnDs [(id,rhs')]
\end{code}
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