Simon's big boxy-type commit

[ghc-hetmet.git] / ghc / compiler / iface / TcIface.lhs

diff --git a/ghc/compiler/iface/TcIface.lhs b/ghc/compiler/iface/TcIface.lhs
index a2cfbed..6726adf 100644 (file)
--- a/ghc/compiler/iface/TcIface.lhs
+++ b/ghc/compiler/iface/TcIface.lhs
@@ -5,41 +5,37 @@
 
 \begin{code}
 module TcIface ( 
 
 \begin{code}
 module TcIface ( 

-       tcImportDecl, typecheckIface, tcIfaceDecl, tcIfaceGlobal,
-       loadImportedInsts, loadImportedRules,
+       tcImportDecl, checkWiredInTyCon, tcHiBootIface, typecheckIface, 
+       tcIfaceDecl, tcIfaceInst, tcIfaceRule, tcIfaceGlobal, 

        tcExtCoreBindings
  ) where
 
 #include "HsVersions.h"
 
 import IfaceSyn
        tcExtCoreBindings
  ) where
 
 #include "HsVersions.h"
 
 import IfaceSyn

-import LoadIface       ( loadHomeInterface, loadInterface, predInstGates,
-                         loadDecls )
+import LoadIface       ( loadInterface, loadWiredInHomeIface,
+                         loadDecls, findAndReadIface )

 import IfaceEnv                ( lookupIfaceTop, lookupIfaceExt, newGlobalBinder, 
                          extendIfaceIdEnv, extendIfaceTyVarEnv, newIPName,
 import IfaceEnv                ( lookupIfaceTop, lookupIfaceExt, newGlobalBinder, 
                          extendIfaceIdEnv, extendIfaceTyVarEnv, newIPName,

-                         tcIfaceTyVar, tcIfaceLclId,
-                         newIfaceName, newIfaceNames )
+                         tcIfaceTyVar, tcIfaceLclId, lookupIfaceTc, 
+                         newIfaceName, newIfaceNames, ifaceExportNames )

 import BuildTyCl       ( buildSynTyCon, buildAlgTyCon, buildDataCon, buildClass,
                          mkAbstractTyConRhs, mkDataTyConRhs, mkNewTyConRhs )
 import TcRnMonad
 import BuildTyCl       ( buildSynTyCon, buildAlgTyCon, buildDataCon, buildClass,
                          mkAbstractTyConRhs, mkDataTyConRhs, mkNewTyConRhs )
 import TcRnMonad

-import TcType          ( hoistForAllTys )      -- TEMPORARY HACK
-import Type            ( liftedTypeKind, splitTyConApp, mkSynTy, mkTyConApp,
-                         mkTyVarTys, mkGenTyConApp, ThetaType, pprClassPred )
+import Type            ( liftedTypeKind, splitTyConApp, mkTyConApp,
+                         mkTyVarTys, ThetaType )

 import TypeRep         ( Type(..), PredType(..) )
 import TypeRep         ( Type(..), PredType(..) )

-import TyCon           ( TyCon, tyConName, isSynTyCon )
-import HscTypes                ( ExternalPackageState(..), EpsStats(..), PackageInstEnv, 
-                         HscEnv, TyThing(..), tyThingClass, tyThingTyCon, 
-                         ModIface(..), ModDetails(..), ModGuts,
-                         extendTypeEnv, lookupTypeEnv, lookupType, typeEnvIds )
-import InstEnv         ( extendInstEnvList )
+import TyCon           ( TyCon, tyConName )
+import HscTypes                ( ExternalPackageState(..), 
+                         TyThing(..), tyThingClass, tyThingTyCon, 
+                         ModIface(..), ModDetails(..), HomeModInfo(..),
+                         emptyModDetails, lookupTypeEnv, lookupType, typeEnvIds )
+import InstEnv         ( Instance(..), mkImportedInstance )

 import CoreSyn
 import CoreSyn

-import PprCore         ( pprIdRules )
-import Rules           ( extendRuleBaseList )

 import CoreUtils       ( exprType )
 import CoreUnfold
 import CoreLint                ( lintUnfolding )
 import WorkWrap                ( mkWrapper )
 import CoreUtils       ( exprType )
 import CoreUnfold
 import CoreLint                ( lintUnfolding )
 import WorkWrap                ( mkWrapper )

-import InstEnv         ( DFunId )

 import Id              ( Id, mkVanillaGlobal, mkLocalId )
 import MkId            ( mkFCallId )
 import IdInfo          ( IdInfo, CafInfo(..), WorkerInfo(..), 
 import Id              ( Id, mkVanillaGlobal, mkLocalId )
 import MkId            ( mkFCallId )
 import IdInfo          ( IdInfo, CafInfo(..), WorkerInfo(..), 

@@ -48,21 +44,21 @@ import IdInfo               ( IdInfo, CafInfo(..), WorkerInfo(..),
                          vanillaIdInfo, newStrictnessInfo )
 import Class           ( Class )
 import TyCon           ( tyConDataCons, isTupleTyCon, mkForeignTyCon )
                          vanillaIdInfo, newStrictnessInfo )
 import Class           ( Class )
 import TyCon           ( tyConDataCons, isTupleTyCon, mkForeignTyCon )

-import DataCon         ( DataCon, dataConWorkId, dataConTyVars, dataConArgTys, isVanillaDataCon )
+import DataCon         ( DataCon, dataConWorkId, dataConTyVars, dataConInstArgTys, isVanillaDataCon )

 import TysWiredIn      ( tupleCon, tupleTyCon, listTyCon, intTyCon, boolTyCon, charTyCon, parrTyCon )
 import Var             ( TyVar, mkTyVar, tyVarKind )
 import TysWiredIn      ( tupleCon, tupleTyCon, listTyCon, intTyCon, boolTyCon, charTyCon, parrTyCon )
 import Var             ( TyVar, mkTyVar, tyVarKind )

-import Name            ( Name, nameModule, nameIsLocalOrFrom, 
-                         isWiredInName, wiredInNameTyThing_maybe, nameParent )
+import Name            ( Name, nameModule, nameIsLocalOrFrom, isWiredInName,
+                         wiredInNameTyThing_maybe, nameParent )

 import NameEnv
 import OccName         ( OccName )
 import NameEnv
 import OccName         ( OccName )

-import Module          ( Module )
+import Module          ( Module, lookupModuleEnv )

 import UniqSupply      ( initUs_ )
 import Outputable      
 import ErrUtils                ( Message )
 import Maybes          ( MaybeErr(..) )
 import SrcLoc          ( noSrcLoc )
 import Util            ( zipWithEqual, dropList, equalLength )
 import UniqSupply      ( initUs_ )
 import Outputable      
 import ErrUtils                ( Message )
 import Maybes          ( MaybeErr(..) )
 import SrcLoc          ( noSrcLoc )
 import Util            ( zipWithEqual, dropList, equalLength )

-import DynFlags        ( DynFlag(..) )
+import DynFlags                ( DynFlag(..), isOneShot )

 \end{code}
 
 This module takes
 \end{code}
 
 This module takes

@@ -110,28 +106,43 @@ also turn out to be needed by the code that e2 expands to.
 
 \begin{code}
 tcImportDecl :: Name -> TcM TyThing
 
 \begin{code}
 tcImportDecl :: Name -> TcM TyThing

--- Entry point for source-code uses of importDecl
+-- Entry point for *source-code* uses of importDecl

 tcImportDecl name 
 tcImportDecl name 

-  = do         { traceIf (text "tcLookupGlobal" <+> ppr name)
+  | Just thing <- wiredInNameTyThing_maybe name
+  = do { initIfaceTcRn (loadWiredInHomeIface name) 
+       ; return thing }
+  | otherwise
+  = do         { traceIf (text "tcImportDecl" <+> ppr name)

        ; mb_thing <- initIfaceTcRn (importDecl name)
        ; case mb_thing of
            Succeeded thing -> return thing
            Failed err      -> failWithTc err }
 
        ; mb_thing <- initIfaceTcRn (importDecl name)
        ; case mb_thing of
            Succeeded thing -> return thing
            Failed err      -> failWithTc err }
 

+checkWiredInTyCon :: TyCon -> TcM ()
+-- Ensure that the home module of the TyCon (and hence its instances)
+-- are loaded. It might not be a wired-in tycon (see the calls in TcUnify),
+-- in which case this is a no-op.
+checkWiredInTyCon tc   
+  | not (isWiredInName tc_name) 
+  = return ()
+  | otherwise
+  = do { mod <- getModule
+       ; if nameIsLocalOrFrom mod tc_name then
+               -- Don't look for (non-existent) Float.hi when
+               -- compiling Float.lhs, which mentions Float of course
+               return ()
+         else  -- A bit yukky to call initIfaceTcRn here
+               initIfaceTcRn (loadWiredInHomeIface tc_name) 
+       }
+  where
+    tc_name = tyConName tc
+

 importDecl :: Name -> IfM lcl (MaybeErr Message TyThing)
 -- Get the TyThing for this Name from an interface file
 importDecl :: Name -> IfM lcl (MaybeErr Message TyThing)
 -- Get the TyThing for this Name from an interface file

-importDecl name 
-  | Just thing <- wiredInNameTyThing_maybe name
-       -- This case definitely happens for tuples, because we
-       -- don't know how many of them we'll find
-       -- It also now happens for all other wired in things.  We used
-       -- to pre-populate the eps_PTE with other wired-in things, but
-       -- we don't seem to do that any more.  I guess it keeps the PTE smaller?
-  = do         { updateEps_ (\ eps -> eps { eps_PTE = extendTypeEnv (eps_PTE eps) thing })
-       ; return (Succeeded thing) }
-
-  | otherwise
-  = do { traceIf nd_doc
+-- It's not a wired-in thing -- the caller caught that
+importDecl name
+  = ASSERT( not (isWiredInName name) )
+    do { traceIf nd_doc

 
        -- Load the interface, which should populate the PTE
        ; mb_iface <- loadInterface nd_doc (nameModule name) ImportBySystem
 
        -- Load the interface, which should populate the PTE
        ; mb_iface <- loadInterface nd_doc (nameModule name) ImportBySystem

@@ -167,11 +178,12 @@ knot.  Remember, the decls aren't necessarily in dependency order --
 and even if they were, the type decls might be mutually recursive.
 
 \begin{code}
 and even if they were, the type decls might be mutually recursive.
 
 \begin{code}

-typecheckIface :: HscEnv
-              -> ModIface      -- Get the decls from here
-              -> IO ModDetails
-typecheckIface hsc_env iface
-  = initIfaceTc hsc_env iface $ \ tc_env_var -> do
+typecheckIface :: ModIface     -- Get the decls from here
+              -> TcRnIf gbl lcl ModDetails
+typecheckIface iface
+  = initIfaceTc iface $ \ tc_env_var -> do
+       -- The tc_env_var is freshly allocated, private to 
+       -- type-checking this particular interface

        {       -- Get the right set of decls and rules.  If we are compiling without -O
                -- we discard pragmas before typechecking, so that we don't "see"
                -- information that we shouldn't.  From a versioning point of view
        {       -- Get the right set of decls and rules.  If we are compiling without -O
                -- we discard pragmas before typechecking, so that we don't "see"
                -- information that we shouldn't.  From a versioning point of view

@@ -193,8 +205,14 @@ typecheckIface hsc_env iface
        ; dfuns <- mapM tcIfaceInst dfuns
        ; rules <- mapM tcIfaceRule rules
 
        ; dfuns <- mapM tcIfaceInst dfuns
        ; rules <- mapM tcIfaceRule rules
 

+               -- Exports
+       ; exports <-  ifaceExportNames (mi_exports iface)
+

                -- Finished
                -- Finished

-       ; return (ModDetails { md_types = type_env, md_insts = dfuns, md_rules = rules }) 
+       ; return (ModDetails {  md_types = type_env, 
+                               md_insts = dfuns,
+                               md_rules = rules,
+                               md_exports = exports }) 

     }
 \end{code}
 
     }
 \end{code}
 

@@ -205,6 +223,74 @@ typecheckIface hsc_env iface
 %*                                                                     *
 %************************************************************************
 
 %*                                                                     *
 %************************************************************************
 

+\begin{code}
+tcHiBootIface :: Module -> TcRn ModDetails
+-- Load the hi-boot iface for the module being compiled,
+-- if it indeed exists in the transitive closure of imports
+-- Return the ModDetails, empty if no hi-boot iface
+tcHiBootIface mod
+  = do         { traceIf (text "loadHiBootInterface" <+> ppr mod)
+
+       ; mode <- getGhciMode
+       ; if not (isOneShot mode)
+               -- In --make and interactive mode, if this module has an hs-boot file
+               -- we'll have compiled it already, and it'll be in the HPT
+               -- 
+               -- We check wheher the interface is a *boot* interface.
+               -- It can happen (when using GHC from Visual Studio) that we
+               -- compile a module in TypecheckOnly mode, with a stable, 
+               -- fully-populated HPT.  In that case the boot interface isn't there
+               -- (it's been replaced by the mother module) so we can't check it.
+               -- And that's fine, because if M's ModInfo is in the HPT, then 
+               -- it's been compiled once, and we don't need to check the boot iface
+         then do { hpt <- getHpt
+                 ; case lookupModuleEnv hpt mod of
+                     Just info | mi_boot (hm_iface info) 
+                               -> return (hm_details info)
+                     other -> return emptyModDetails }
+         else do
+
+       -- OK, so we're in one-shot mode.  
+       -- In that case, we're read all the direct imports by now, 
+       -- so eps_is_boot will record if any of our imports mention us by 
+       -- way of hi-boot file
+       { eps <- getEps
+       ; case lookupModuleEnv (eps_is_boot eps) mod of {
+           Nothing -> return emptyModDetails ; -- The typical case
+
+           Just (_, False) -> failWithTc moduleLoop ;
+               -- Someone below us imported us!
+               -- This is a loop with no hi-boot in the way
+               
+           Just (mod, True) ->         -- There's a hi-boot interface below us
+               
+    do { read_result <- findAndReadIface 
+                               True    -- Explicit import? 
+                               need mod
+                               True    -- Hi-boot file
+
+       ; case read_result of
+               Failed err               -> failWithTc (elaborate err)
+               Succeeded (iface, _path) -> typecheckIface iface
+    }}}}
+  where
+    need = ptext SLIT("Need the hi-boot interface for") <+> ppr mod
+                <+> ptext SLIT("to compare against the Real Thing")
+
+    moduleLoop = ptext SLIT("Circular imports: module") <+> quotes (ppr mod) 
+                    <+> ptext SLIT("depends on itself")
+
+    elaborate err = hang (ptext SLIT("Could not find hi-boot interface for") <+> 
+                         quotes (ppr mod) <> colon) 4 err
+\end{code}
+
+
+%************************************************************************
+%*                                                                     *
+               Type and class declarations
+%*                                                                     *
+%************************************************************************
+

 When typechecking a data type decl, we *lazily* (via forkM) typecheck
 the constructor argument types.  This is in the hope that we may never
 poke on those argument types, and hence may never need to load the
 When typechecking a data type decl, we *lazily* (via forkM) typecheck
 the constructor argument types.  This is in the hope that we may never
 poke on those argument types, and hence may never need to load the

@@ -260,6 +346,7 @@ tcIfaceDecl (IfaceId {ifName = occ_name, ifType = iface_type, ifIdInfo = info})
 
 tcIfaceDecl (IfaceData {ifName = occ_name, 
                        ifTyVars = tv_bndrs, 
 
 tcIfaceDecl (IfaceData {ifName = occ_name, 
                        ifTyVars = tv_bndrs, 

+                       ifCtxt = ctxt,

                        ifCons = rdr_cons, 
                        ifVrcs = arg_vrcs, ifRec = is_rec, 
                        ifGeneric = want_generic })
                        ifCons = rdr_cons, 
                        ifVrcs = arg_vrcs, ifRec = is_rec, 
                        ifGeneric = want_generic })

@@ -267,10 +354,10 @@ tcIfaceDecl (IfaceData {ifName = occ_name,
        ; bindIfaceTyVars tv_bndrs $ \ tyvars -> do
 
        { tycon <- fixM ( \ tycon -> do
        ; bindIfaceTyVars tv_bndrs $ \ tyvars -> do
 
        { tycon <- fixM ( \ tycon -> do

-           { cons  <- tcIfaceDataCons tycon tyvars rdr_cons
-           ; tycon <- buildAlgTyCon tc_name tyvars cons 
-                           arg_vrcs is_rec want_generic
-           ; return tycon
+           { stupid_theta <- tcIfaceCtxt ctxt
+           ; cons  <- tcIfaceDataCons tycon tyvars rdr_cons
+           ; buildAlgTyCon tc_name tyvars stupid_theta
+                           cons arg_vrcs is_rec want_generic

            })
         ; traceIf (text "tcIfaceDecl4" <+> ppr tycon)
        ; return (ATyCon tycon)
            })
         ; traceIf (text "tcIfaceDecl4" <+> ppr tycon)
        ; return (ATyCon tycon)

@@ -316,16 +403,12 @@ tcIfaceDecl (IfaceForeign {ifName = rdr_name, ifExtName = ext_name})
 
 tcIfaceDataCons tycon tc_tyvars if_cons
   = case if_cons of
 
 tcIfaceDataCons tycon tc_tyvars if_cons
   = case if_cons of

-       IfAbstractTyCon          -> return mkAbstractTyConRhs
-       IfDataTyCon mb_ctxt cons -> do  { mb_theta <- tc_ctxt mb_ctxt
-                                       ; data_cons <- mappM tc_con_decl cons
-                                       ; return (mkDataTyConRhs mb_theta data_cons) }
-       IfNewTyCon con           -> do  { data_con <- tc_con_decl con
-                                       ; return (mkNewTyConRhs tycon data_con) }
+       IfAbstractTyCon  -> return mkAbstractTyConRhs
+       IfDataTyCon cons -> do  { data_cons <- mappM tc_con_decl cons
+                               ; return (mkDataTyConRhs data_cons) }
+       IfNewTyCon con   -> do  { data_con <- tc_con_decl con
+                               ; return (mkNewTyConRhs tycon data_con) }

   where
   where

-    tc_ctxt Nothing     = return Nothing
-    tc_ctxt (Just ctxt) = do { theta <- tcIfaceCtxt ctxt; return (Just theta) }
-

     tc_con_decl (IfVanillaCon {        ifConOcc = occ, ifConInfix = is_infix, ifConArgTys = args, 
                                ifConStricts = stricts, ifConFields = field_lbls})
       = do { name  <- lookupIfaceTop occ
     tc_con_decl (IfVanillaCon {        ifConOcc = occ, ifConInfix = is_infix, ifConArgTys = args, 
                                ifConStricts = stricts, ifConFields = field_lbls})
       = do { name  <- lookupIfaceTop occ

@@ -375,118 +458,22 @@ tcIfaceDataCons tycon tc_tyvars if_cons
 %*                                                                     *
 %************************************************************************
 
 %*                                                                     *
 %************************************************************************
 

-The gating story for instance declarations
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-When we are looking for a dict (C t1..tn), we slurp in instance decls for
-C that 
-       mention at least one of the type constructors 
-       at the roots of t1..tn
-
-Why "at least one" rather than "all"?  Because functional dependencies 
-complicate the picture.  Consider
-       class C a b | a->b where ...
-       instance C Foo Baz where ...
-Here, the gates are really only C and Foo, *not* Baz.
-That is, if C and Foo are visible, even if Baz isn't, we must
-slurp the decl, even if Baz is thus far completely unknown to the
-system.
-
-Why "roots of the types"?  Reason is overlap.  For example, suppose there 
-are interfaces in the pool for
-  (a)  C Int b
- (b)   C a [b]
-  (c)  C a [T] 
-Then, if we are trying to resolve (C Int x), we need (a)
-if we are trying to resolve (C x [y]), we need *both* (b) and (c),
-even though T is not involved yet, so that we spot the overlap.
-
-
-NOTE: if you use an instance decl with NO type constructors
-       instance C a where ...
-and look up an Inst that only has type variables such as (C (n o))
-then GHC won't necessarily suck in the instances that overlap with this.
-
-

 \begin{code}
 \begin{code}

-loadImportedInsts :: Class -> [Type] -> TcM PackageInstEnv
-loadImportedInsts cls tys
-  = do {       -- Get interfaces for wired-in things, such as Integer
-               -- Any non-wired-in tycons will already be loaded, else
-               -- we couldn't have them in the Type
-       ; this_mod <- getModule 
-       ; let { (cls_gate, tc_gates) = predInstGates cls tys
-             ; imp_wi n = isWiredInName n && this_mod /= nameModule n
-             ; wired_tcs = filter imp_wi tc_gates }
-                       -- Wired-in tycons not from this module.  The "this-module"
-                       -- test bites only when compiling Base etc, because loadHomeInterface
-                       -- barfs if it's asked to load a non-existent interface
-       ; if null wired_tcs then returnM ()
-         else initIfaceTcRn (mapM_ (loadHomeInterface wired_doc) wired_tcs)
-
-               -- Now suck in the relevant instances
-       ; iface_insts <- updateEps (selectInsts cls_gate tc_gates)
-
-       -- Empty => finish up rapidly, without writing to eps
-       ; if null iface_insts then
-               do { eps <- getEps; return (eps_inst_env eps) }
-         else do
-       { traceIf (sep [ptext SLIT("Importing instances for") <+> pprClassPred cls tys, 
-                       nest 2 (vcat [ppr i | (_,_,i) <- iface_insts])])
-
-       -- Typecheck the new instances
-       ; dfuns <- initIfaceTcRn (mappM tc_inst iface_insts)
-
-       -- And put them in the package instance environment
-       ; updateEps ( \ eps ->
-           let 
-               inst_env' = extendInstEnvList (eps_inst_env eps) dfuns
-           in
-           (eps { eps_inst_env = inst_env' }, inst_env')
-       )}}
+tcIfaceInst :: IfaceInst -> IfL Instance
+tcIfaceInst (IfaceInst { ifDFun = dfun_occ, ifOFlag = oflag,
+                        ifInstCls = cls, ifInstTys = mb_tcs,
+                        ifInstOrph = orph })
+  = do { dfun    <- forkM (ptext SLIT("Dict fun") <+> ppr dfun_occ) $
+                    tcIfaceExtId (LocalTop dfun_occ)
+       ; cls'    <- lookupIfaceExt cls
+       ; mb_tcs' <- mapM do_tc mb_tcs
+       ; return (mkImportedInstance cls' mb_tcs' orph dfun oflag) }

   where
   where

-    wired_doc = ptext SLIT("Need home inteface for wired-in thing")
-
-tc_inst (mod, loc, inst) = initIfaceLcl mod full_loc (tcIfaceInst inst)
-  where
-    full_loc = loc $$ (nest 2 (ptext SLIT("instance decl") <+> ppr inst))
-
-tcIfaceInst :: IfaceInst -> IfL DFunId
-tcIfaceInst (IfaceInst { ifDFun = dfun_occ })
-  = tcIfaceExtId (LocalTop dfun_occ)
-
-selectInsts :: Name -> [Name] -> ExternalPackageState 
-           -> (ExternalPackageState, [(Module, SDoc, IfaceInst)])
-selectInsts cls tycons eps
-  = (eps { eps_insts = insts', eps_stats = stats' }, iface_insts)
-  where
-    insts  = eps_insts eps
-    stats  = eps_stats eps
-    stats' = stats { n_insts_out = n_insts_out stats + length iface_insts } 
-
-    (insts', iface_insts) 
-       = case lookupNameEnv insts cls of {
-               Nothing -> (insts, []) ;
-               Just gated_insts ->
-       
-         case choose1 gated_insts  of {
-           (_, []) -> (insts, []) ;    -- None picked
-           (gated_insts', iface_insts') -> 
-
-         (extendNameEnv insts cls gated_insts', iface_insts') }}
-
-    choose1 gated_insts
-       | null tycons                   -- Bizarre special case of C (a b); then there are no tycons
-       = ([], map snd gated_insts)     -- Just grab all the instances, no real alternative
-       | otherwise                     -- Normal case
-       = foldl choose2 ([],[]) gated_insts
-
-       -- Reverses the gated decls, but that doesn't matter
-    choose2 (gis, decls) (gates, decl)
-       |  null gates   -- Happens when we have 'instance T a where ...'
-        || any (`elem` tycons) gates = (gis,              decl:decls)
-       | otherwise                  = ((gates,decl) : gis, decls)
+    do_tc Nothing   = return Nothing
+    do_tc (Just tc) = do { tc' <- lookupIfaceTc tc; return (Just tc') }

 \end{code}
 
 \end{code}
 

+

 %************************************************************************
 %*                                                                     *
                Rules
 %************************************************************************
 %*                                                                     *
                Rules

@@ -498,77 +485,40 @@ are in the type environment.  However, remember that typechecking a Rule may
 (as a side effect) augment the type envt, and so we may need to iterate the process.
 
 \begin{code}
 (as a side effect) augment the type envt, and so we may need to iterate the process.
 
 \begin{code}

-loadImportedRules :: HscEnv -> ModGuts -> IO [IdCoreRule]
--- Returns just the new rules added
-loadImportedRules hsc_env guts
-  = initIfaceRules hsc_env guts $ do 
-       { -- Get new rules
-         if_rules <- updateEps selectRules
-
-       ; traceIf (ptext SLIT("Importing rules:") <+> vcat [ppr r | (_,_,r) <- if_rules])
-
-       ; core_rules <- mapM tc_rule if_rules
-
-       -- Debug print
-       ; traceIf (ptext SLIT("Imported rules:") <+> pprIdRules core_rules)
-       
-       -- Update the rule base and return it
-       ; updateEps (\ eps -> 
-           let { new_rule_base = extendRuleBaseList (eps_rule_base eps) core_rules }
-           in (eps { eps_rule_base = new_rule_base }, new_rule_base)
-         ) 
-
-       -- Strictly speaking, at this point we should go round again, since
-       -- typechecking one set of rules may bring in new things which enable
-       -- some more rules to come in.  But we call loadImportedRules several
-       -- times anyway, so I'm going to be lazy and ignore this.
-       ; return core_rules
-    }
-
-tc_rule (mod, loc, rule) = initIfaceLcl mod full_loc (tcIfaceRule rule)
-  where
-    full_loc = loc $$ (nest 2 (ptext SLIT("rule") <+> ppr rule))
-   
-selectRules :: ExternalPackageState -> (ExternalPackageState, [(Module, SDoc, IfaceRule)])
--- Not terribly efficient.  Look at each rule in the pool to see if
--- all its gates are in the type env.  If so, take it out of the pool.
--- If not, trim its gates for next time.
-selectRules eps
-  = (eps { eps_rules = rules', eps_stats = stats' }, if_rules)
-  where
-    stats    = eps_stats eps
-    rules    = eps_rules eps
-    type_env = eps_PTE eps
-    stats'   = stats { n_rules_out = n_rules_out stats + length if_rules }
-
-    (rules', if_rules) = foldl do_one ([], []) rules
-
-    do_one (pool, if_rules) (gates, rule)
-       | null gates' = (pool, rule:if_rules)
-       | otherwise   = ((gates',rule) : pool, if_rules)
-       where
-         gates' = filter (not . (`elemNameEnv` type_env)) gates
-
-
-tcIfaceRule :: IfaceRule -> IfL IdCoreRule
-tcIfaceRule (IfaceRule {ifRuleName = rule_name, ifActivation = act, ifRuleBndrs = bndrs,
-                       ifRuleHead = fn_rdr, ifRuleArgs = args, ifRuleRhs = rhs })
-  = bindIfaceBndrs bndrs       $ \ bndrs' ->
-    do { fn <- tcIfaceExtId fn_rdr
-       ; args' <- mappM tcIfaceExpr args
-       ; rhs'  <- tcIfaceExpr rhs
-       ; let rule = Rule rule_name act bndrs' args' rhs'
-       ; returnM (IdCoreRule fn (isOrphNm fn_rdr) rule) }
+tcIfaceRule :: IfaceRule -> IfL CoreRule
+tcIfaceRule (IfaceRule {ifRuleName = name, ifActivation = act, ifRuleBndrs = bndrs,
+                       ifRuleHead = fn, ifRuleArgs = args, ifRuleRhs = rhs,
+                       ifRuleOrph = orph })
+  = do { fn' <- lookupIfaceExt fn
+       ; ~(bndrs', args', rhs') <- 
+               -- Typecheck the payload lazily, in the hope it'll never be looked at
+               forkM (ptext SLIT("Rule") <+> ftext name) $
+               bindIfaceBndrs bndrs                      $ \ bndrs' ->
+               do { args' <- mappM tcIfaceExpr args
+                  ; rhs'  <- tcIfaceExpr rhs
+                  ; return (bndrs', args', rhs') }
+       ; mb_tcs <- mapM ifTopFreeName args
+       ; returnM (Rule { ru_name = name, ru_fn = fn', ru_act = act, 
+                         ru_bndrs = bndrs', ru_args = args', 
+                         ru_rhs = rhs', ru_orph = orph,
+                         ru_rough = mb_tcs,
+                         ru_local = isLocalIfaceExtName fn }) }

   where
   where

-
-tcIfaceRule (IfaceBuiltinRule fn_rdr core_rule)
-  = do { fn <- tcIfaceExtId fn_rdr
-       ; returnM (IdCoreRule fn (isOrphNm fn_rdr) core_rule) }
-
-isOrphNm :: IfaceExtName -> Bool
--- An orphan name comes from somewhere other than this module,
--- so it has a non-local name
-isOrphNm name = not (isLocalIfaceExtName name)
+       -- This function *must* mirror exactly what Rules.topFreeName does
+       -- We could have stored the ru_rough field in the iface file
+       -- but that would be redundant, I think.
+       -- The only wrinkle is that we must not be deceived by
+       -- type syononyms at the top of a type arg.  Since
+       -- we can't tell at this point, we are careful not
+       -- to write them out in coreRuleToIfaceRule
+    ifTopFreeName :: IfaceExpr -> IfL (Maybe Name)
+    ifTopFreeName (IfaceType (IfaceTyConApp tc _ ))
+       = do { n <- lookupIfaceTc tc
+            ; return (Just n) }
+    ifTopFreeName (IfaceApp f a) = ifTopFreeName f
+    ifTopFreeName (IfaceExt ext) = do { n <- lookupIfaceExt ext
+                                     ; return (Just n) }
+    ifTopFreeName other = return Nothing

 \end{code}
 
 
 \end{code}
 
 

@@ -583,21 +533,12 @@ tcIfaceType :: IfaceType -> IfL Type
 tcIfaceType (IfaceTyVar n)        = do { tv <- tcIfaceTyVar n; return (TyVarTy tv) }
 tcIfaceType (IfaceAppTy t1 t2)    = do { t1' <- tcIfaceType t1; t2' <- tcIfaceType t2; return (AppTy t1' t2') }
 tcIfaceType (IfaceFunTy t1 t2)    = do { t1' <- tcIfaceType t1; t2' <- tcIfaceType t2; return (FunTy t1' t2') }
 tcIfaceType (IfaceTyVar n)        = do { tv <- tcIfaceTyVar n; return (TyVarTy tv) }
 tcIfaceType (IfaceAppTy t1 t2)    = do { t1' <- tcIfaceType t1; t2' <- tcIfaceType t2; return (AppTy t1' t2') }
 tcIfaceType (IfaceFunTy t1 t2)    = do { t1' <- tcIfaceType t1; t2' <- tcIfaceType t2; return (FunTy t1' t2') }

-tcIfaceType (IfaceTyConApp tc ts) = do { tc' <- tcIfaceTyCon tc; ts' <- tcIfaceTypes ts; return (mkIfTcApp tc' ts') }
+tcIfaceType (IfaceTyConApp tc ts) = do { tc' <- tcIfaceTyCon tc; ts' <- tcIfaceTypes ts; return (mkTyConApp tc' ts') }

 tcIfaceType (IfaceForAllTy tv t)  = bindIfaceTyVar tv $ \ tv' -> do { t' <- tcIfaceType t; return (ForAllTy tv' t') }
 tcIfaceType (IfacePredTy st)      = do { st' <- tcIfacePredType st; return (PredTy st') }
 
 tcIfaceTypes tys = mapM tcIfaceType tys
 
 tcIfaceType (IfaceForAllTy tv t)  = bindIfaceTyVar tv $ \ tv' -> do { t' <- tcIfaceType t; return (ForAllTy tv' t') }
 tcIfaceType (IfacePredTy st)      = do { st' <- tcIfacePredType st; return (PredTy st') }
 
 tcIfaceTypes tys = mapM tcIfaceType tys
 

-mkIfTcApp :: TyCon -> [Type] -> Type
--- In interface files we retain type synonyms (for brevity and better error
--- messages), but type synonyms can expand into non-hoisted types (ones with
--- foralls to the right of an arrow), so we must be careful to hoist them here.
--- This hack should go away when we get rid of hoisting.
-mkIfTcApp tc tys
-  | isSynTyCon tc = hoistForAllTys (mkSynTy tc tys)
-  | otherwise    = mkTyConApp tc tys
-

 -----------------------------------------
 tcIfacePredType :: IfacePredType -> IfL PredType
 tcIfacePredType (IfaceClassP cls ts) = do { cls' <- tcIfaceClass cls; ts' <- tcIfaceTypes ts; return (ClassP cls' ts') }
 -----------------------------------------
 tcIfacePredType :: IfacePredType -> IfL PredType
 tcIfacePredType (IfaceClassP cls ts) = do { cls' <- tcIfaceClass cls; ts' <- tcIfaceTypes ts; return (ClassP cls' ts') }

@@ -729,7 +670,7 @@ tcIfaceAlt (tycon, inst_tys) (IfaceDataAlt data_occ, arg_occs, rhs)
          arg_names <- newIfaceNames arg_occs
        ; let   tyvars   = [ mkTyVar name (tyVarKind tv) 
                           | (name,tv) <- arg_names `zip` dataConTyVars con] 
          arg_names <- newIfaceNames arg_occs
        ; let   tyvars   = [ mkTyVar name (tyVarKind tv) 
                           | (name,tv) <- arg_names `zip` dataConTyVars con] 

-               arg_tys  = dataConArgTys con (mkTyVarTys tyvars)
+               arg_tys  = dataConInstArgTys con (mkTyVarTys tyvars)

                id_names = dropList tyvars arg_names
                arg_ids  = ASSERT2( equalLength id_names arg_tys,
                                    ppr (con, arg_names, rhs) $$ ppr tyvars $$ ppr arg_tys )
                id_names = dropList tyvars arg_names
                arg_ids  = ASSERT2( equalLength id_names arg_tys,
                                    ppr (con, arg_names, rhs) $$ ppr tyvars $$ ppr arg_tys )

@@ -747,7 +688,7 @@ tcIfaceAlt (tycon, inst_tys) (IfaceTupleAlt boxity, arg_occs, rhs)
 
 tcVanillaAlt data_con inst_tys arg_occs rhs
   = do { arg_names <- newIfaceNames arg_occs
 
 tcVanillaAlt data_con inst_tys arg_occs rhs
   = do { arg_names <- newIfaceNames arg_occs

-       ; let arg_tys = dataConArgTys data_con inst_tys
+       ; let arg_tys = dataConInstArgTys data_con inst_tys

        ; let arg_ids = ASSERT2( equalLength arg_names arg_tys,
                                 ppr data_con <+> ppr inst_tys <+> ppr arg_occs $$ ppr rhs )
                        zipWith mkLocalId arg_names arg_tys
        ; let arg_ids = ASSERT2( equalLength arg_names arg_tys,
                                 ppr data_con <+> ppr inst_tys <+> ppr arg_occs $$ ppr rhs )
                        zipWith mkLocalId arg_names arg_tys

@@ -884,6 +825,13 @@ tcPragExpr name expr
 \begin{code}
 tcIfaceGlobal :: Name -> IfL TyThing
 tcIfaceGlobal name
 \begin{code}
 tcIfaceGlobal :: Name -> IfL TyThing
 tcIfaceGlobal name

+  | Just thing <- wiredInNameTyThing_maybe name
+       -- Wired-in things include TyCons, DataCons, and Ids
+  = do { loadWiredInHomeIface name; return thing }
+       -- Even though we are in an interface file, we want to make
+       -- sure its instances are loaded (imagine f :: Double -> Double)
+       -- and its RULES are loaded too
+  | otherwise

   = do { (eps,hpt) <- getEpsAndHpt
        ; case lookupType hpt (eps_PTE eps) name of {
            Just thing -> return thing ;
   = do { (eps,hpt) <- getEpsAndHpt
        ; case lookupType hpt (eps_PTE eps) name of {
            Just thing -> return thing ;

@@ -909,15 +857,30 @@ tcIfaceGlobal name
     }}}}}
 
 tcIfaceTyCon :: IfaceTyCon -> IfL TyCon
     }}}}}
 
 tcIfaceTyCon :: IfaceTyCon -> IfL TyCon

-tcIfaceTyCon IfaceIntTc  = return intTyCon
-tcIfaceTyCon IfaceBoolTc = return boolTyCon
-tcIfaceTyCon IfaceCharTc = return charTyCon
-tcIfaceTyCon IfaceListTc = return listTyCon
-tcIfaceTyCon IfacePArrTc = return parrTyCon
-tcIfaceTyCon (IfaceTupTc bx ar) = return (tupleTyCon bx ar)
-tcIfaceTyCon (IfaceTc ext_nm) = do { name <- lookupIfaceExt ext_nm
-                                  ; thing <- tcIfaceGlobal name
-                                  ; return (tyThingTyCon thing) }
+tcIfaceTyCon IfaceIntTc        = tcWiredInTyCon intTyCon
+tcIfaceTyCon IfaceBoolTc       = tcWiredInTyCon boolTyCon
+tcIfaceTyCon IfaceCharTc       = tcWiredInTyCon charTyCon
+tcIfaceTyCon IfaceListTc       = tcWiredInTyCon listTyCon
+tcIfaceTyCon IfacePArrTc       = tcWiredInTyCon parrTyCon
+tcIfaceTyCon (IfaceTupTc bx ar) = tcWiredInTyCon (tupleTyCon bx ar)
+tcIfaceTyCon (IfaceTc ext_nm)   = do { name <- lookupIfaceExt ext_nm
+                                    ; thing <- tcIfaceGlobal name 
+                                    ; return (check_tc (tyThingTyCon thing)) }
+  where
+#ifdef DEBUG
+    check_tc tc = case toIfaceTyCon (error "urk") tc of
+                  IfaceTc _ -> tc
+                  other     -> pprTrace "check_tc" (ppr tc) tc
+#else
+    check_tc tc = tc
+#endif
+
+-- Even though we are in an interface file, we want to make
+-- sure the instances and RULES of this tycon are loaded 
+-- Imagine: f :: Double -> Double
+tcWiredInTyCon :: TyCon -> IfL TyCon
+tcWiredInTyCon tc = do { loadWiredInHomeIface (tyConName tc)
+                      ; return tc }

 
 tcIfaceClass :: IfaceExtName -> IfL Class
 tcIfaceClass rdr_name = do { name <- lookupIfaceExt rdr_name
 
 tcIfaceClass :: IfaceExtName -> IfL Class
 tcIfaceClass rdr_name = do { name <- lookupIfaceExt rdr_name