import Inst ( InstOrigin(..), newDicts, instToId,
LIE, mkLIE, emptyLIE, plusLIE, plusLIEs )
import TcDeriv ( tcDeriving )
-import TcEnv ( TcEnv, tcExtendGlobalValEnv,
+import TcEnv ( TcEnv, tcExtendGlobalValEnv, isLocalThing,
tcExtendTyVarEnvForMeths, tcLookupId, tcLookupClass,
InstInfo(..), pprInstInfo, simpleInstInfoTyCon,
simpleInstInfoTy, newDFunName
Gather up the instance declarations from their various sources
\begin{code}
-tcInstDecls1 :: PackageInstEnv
- -> PersistentRenamerState
- -> HomeSymbolTable -- Contains instances
- -> TcEnv -- Contains IdInfo for dfun ids
- -> (Name -> Maybe Fixity) -- for deriving Show and Read
- -> Module -- Module for deriving
- -> [RenamedHsDecl]
- -> TcM (PackageInstEnv, InstEnv, [InstInfo], RenamedHsBinds)
+tcInstDecls1
+ :: PackageInstEnv
+ -> PersistentRenamerState
+ -> HomeSymbolTable -- Contains instances
+ -> TcEnv -- Contains IdInfo for dfun ids
+ -> (Name -> Maybe Fixity) -- for deriving Show and Read
+ -> Module -- Module for deriving
+ -> [RenamedHsDecl]
+ -> TcM (PackageInstEnv, -- cached package inst env
+ InstEnv, -- the full inst env
+ [InstInfo], -- instance decls to process
+ [DFunId], -- instances from this module, for its iface
+ RenamedHsBinds) -- derived instances
tcInstDecls1 inst_env0 prs hst unf_env get_fixity this_mod decls
= let
inst_decls = [inst_decl | InstD inst_decl <- decls]
tycl_decls = [decl | TyClD decl <- decls]
clas_decls = filter isClassDecl tycl_decls
- (imported_inst_ds, local_inst_ds) = partition isIfaceInstDecl inst_decls
+ (iface_inst_ds, local_inst_ds) = partition isIfaceInstDecl inst_decls
in
-- (1) Do the ordinary instance declarations
- mapNF_Tc tcLocalInstDecl1 local_inst_ds `thenNF_Tc` \ local_inst_infos ->
- mapNF_Tc tcImportedInstDecl1 imported_inst_ds `thenNF_Tc` \ imported_dfuns ->
+ mapNF_Tc tcLocalInstDecl1 local_inst_ds `thenNF_Tc` \ local_inst_infos ->
+ mapNF_Tc tcImportedInstDecl1 iface_inst_ds `thenNF_Tc` \ iface_dfuns ->
-- (2) Instances from generic class declarations
- getGenericInstances clas_decls `thenTc` \ generic_inst_info ->
+ getGenericInstances clas_decls `thenTc` \ generic_inst_info ->
-- Next, construct the instance environment so far, consisting of
- -- a) cached non-home-package InstEnv (gotten from pcs) pcs_insts pcs
- -- b) imported instance decls (not in the home package) inst_env1
- -- c) other modules in this package (gotten from hst) inst_env2
- -- d) local instance decls inst_env3
- -- e) generic instances inst_env4
+ -- a) cached non-home-package InstEnv (gotten from pcs) inst_env0
+ -- b) imported instance decls (not in the home package) inst_env1
+ -- c) other modules in this package (gotten from hst) inst_env2
+ -- d) imported instance decls (from this module) inst_env3
+ -- e) local instance decls inst_env4
+ -- f) generic instances inst_env5
-- The result of (b) replaces the cached InstEnv in the PCS
+ --
+ -- Note that iface_dfuns may contain not only insts that we
+ -- demand-loaded from interface files, but also instances from
+ -- the current module in the case where we are loading this
+ -- module's interface file in GHCi, so we partition the
+ -- iface_dfuns into non-local and local instances so that we
+ -- don't end up with home package instances in the PCS.
+ --
+ -- There can't be any instance declarations from the home
+ -- package other than from the current module (with the
+ -- compilation manager) because they are loaded explicitly by
+ -- the compilation manager.
let
local_inst_info = catMaybes local_inst_infos
- hst_dfuns = foldModuleEnv ((++) . md_insts) [] hst
+ (local_iface_dfuns, pkg_iface_dfuns)
+ = partition (isLocalThing this_mod) iface_dfuns
+ hst_dfuns = foldModuleEnv ((++) . md_insts) [] hst
in
-- pprTrace "tcInstDecls" (vcat [ppr imported_dfuns, ppr hst_dfuns]) $
- addInstDFuns inst_env0 imported_dfuns `thenNF_Tc` \ inst_env1 ->
+ addInstDFuns inst_env0 pkg_iface_dfuns `thenNF_Tc` \ inst_env1 ->
addInstDFuns inst_env1 hst_dfuns `thenNF_Tc` \ inst_env2 ->
- addInstInfos inst_env2 local_inst_info `thenNF_Tc` \ inst_env3 ->
- addInstInfos inst_env3 generic_inst_info `thenNF_Tc` \ inst_env4 ->
+ addInstDFuns inst_env2 local_iface_dfuns `thenNF_Tc` \ inst_env3 ->
+ addInstInfos inst_env3 local_inst_info `thenNF_Tc` \ inst_env4 ->
+ addInstInfos inst_env4 generic_inst_info `thenNF_Tc` \ inst_env5 ->
-- (3) Compute instances from "deriving" clauses;
-- note that we only do derivings for things in this module;
-- we ignore deriving decls from interfaces!
-- This stuff computes a context for the derived instance decl, so it
- -- needs to know about all the instances possible; hence inst_env4
- tcDeriving prs this_mod inst_env4 get_fixity tycl_decls
- `thenTc` \ (deriv_inst_info, deriv_binds) ->
- addInstInfos inst_env4 deriv_inst_info `thenNF_Tc` \ final_inst_env ->
+ -- needs to know about all the instances possible; hence inst_env5
+ tcDeriving prs this_mod inst_env5 get_fixity tycl_decls
+ `thenTc` \ (deriv_inst_info, deriv_binds) ->
+ addInstInfos inst_env5 deriv_inst_info `thenNF_Tc` \ final_inst_env ->
+ let inst_info = generic_inst_info ++ deriv_inst_info ++ local_inst_info in
returnTc (inst_env1,
final_inst_env,
- generic_inst_info ++ deriv_inst_info ++ local_inst_info,
+ inst_info,
+ local_iface_dfuns ++ map iDFunId inst_info,
deriv_binds)
addInstInfos :: InstEnv -> [InstInfo] -> NF_TcM InstEnv
(HsVar unsafeCoerceId `TyApp` [idType rep_dict_id, inst_head'])
`HsApp`
(HsVar rep_dict_id)
+ -- You might wonder why we have the 'coerce'. It's because the
+ -- type equality mechanism isn't clever enough; see comments with Type.eqType.
+ -- So Lint complains if we don't have this.
in
returnTc (emptyLIE, VarMonoBind dfun_id body)
projects / ghc-hetmet.git / blobdiff