\section[TcInstDecls]{Typechecking instance declarations}
\begin{code}
-module TcInstDcls ( tcInstDecls1, tcIfaceInstDecls,
- tcInstDecls2, tcAddDeclCtxt ) where
+module TcInstDcls ( tcInstDecls1, tcInstDecls2 ) where
#include "HsVersions.h"
-
-import CmdLineOpts ( DynFlag(..) )
-
-import HsSyn ( InstDecl(..), TyClDecl(..), HsType(..),
- MonoBinds(..), HsExpr(..), HsLit(..), Sig(..), HsTyVarBndr(..),
+import HsSyn ( InstDecl(..), HsType(..),
+ MonoBinds(..), HsExpr(..), HsLit(..), Sig(..),
andMonoBindList, collectMonoBinders,
- isClassDecl, isSourceInstDecl, toHsType
- )
-import RnHsSyn ( RenamedHsBinds, RenamedInstDecl,
- RenamedMonoBinds, RenamedTyClDecl, RenamedHsType,
- extractHsTyVars, maybeGenericMatch
+ isClassDecl
)
+import RnHsSyn ( RenamedHsBinds, RenamedInstDecl, RenamedTyClDecl )
import TcHsSyn ( TcMonoBinds, mkHsConApp )
import TcBinds ( tcSpecSigs )
-import TcClassDcl ( tcMethodBind, mkMethodBind, badMethodErr )
+import TcClassDcl ( tcMethodBind, mkMethodBind, badMethodErr,
+ tcClassDecl2, getGenericInstances )
import TcRnMonad
import TcMType ( tcInstType, checkValidTheta, checkValidInstHead, instTypeErr,
- checkAmbiguity, UserTypeCtxt(..), SourceTyCtxt(..) )
-import TcType ( mkClassPred, mkTyVarTy, tcSplitForAllTys, tyVarsOfType,
+ checkAmbiguity, SourceTyCtxt(..) )
+import TcType ( mkClassPred, tcSplitForAllTys, tyVarsOfType,
tcSplitSigmaTy, getClassPredTys, tcSplitPredTy_maybe, mkTyVarTys,
- TyVarDetails(..)
- )
-import Inst ( InstOrigin(..), tcInstClassOp, newDicts, instToId, showLIE )
+ TyVarDetails(..), tcSplitDFunTy, pprClassPred )
+import Inst ( InstOrigin(..), tcInstClassOp, newDicts, instToId,
+ showLIE, tcExtendLocalInstEnv )
import TcDeriv ( tcDeriving )
-import TcEnv ( tcExtendGlobalValEnv,
- tcLookupClass, tcExtendTyVarEnv2,
- tcExtendInstEnv, tcExtendLocalInstEnv, tcLookupGlobalId,
- InstInfo(..), InstBindings(..), pprInstInfo, simpleInstInfoTyCon,
- simpleInstInfoTy, newDFunName
+import TcEnv ( tcExtendGlobalValEnv, tcExtendTyVarEnv2,
+ InstInfo(..), InstBindings(..),
+ newDFunName, tcExtendLocalValEnv
)
-import PprType ( pprClassPred )
-import TcMonoType ( tcHsTyVars, kcHsSigType, tcHsType, tcHsSigType )
+import TcHsType ( kcHsSigType, tcHsKindedType )
import TcUnify ( checkSigTyVars )
import TcSimplify ( tcSimplifyCheck, tcSimplifyTop )
-import HscTypes ( DFunId )
import Subst ( mkTyVarSubst, substTheta, substTy )
import DataCon ( classDataCon )
-import Class ( Class, classBigSig )
+import Class ( classBigSig )
import Var ( idName, idType )
import NameSet
import MkId ( mkDictFunId, rUNTIME_ERROR_ID )
import FunDeps ( checkInstFDs )
-import Generics ( validGenericInstanceType )
import Name ( getSrcLoc )
import NameSet ( unitNameSet, emptyNameSet, nameSetToList )
-import TyCon ( TyCon )
-import TysWiredIn ( genericTyCons )
-import SrcLoc ( SrcLoc )
-import Unique ( Uniquable(..) )
-import Util ( lengthExceeds )
-import BasicTypes ( NewOrData(..) )
import UnicodeUtil ( stringToUtf8 )
-import ErrUtils ( dumpIfSet_dyn )
-import ListSetOps ( Assoc, emptyAssoc, plusAssoc_C, mapAssoc,
- assocElts, extendAssoc_C, equivClassesByUniq, minusList
- )
import Maybe ( catMaybes )
-import List ( partition )
+import ListSetOps ( minusList )
import Outputable
import FastString
\end{code}
-> TcM (TcGblEnv, -- The full inst env
[InstInfo], -- Source-code instance decls to process;
-- contains all dfuns for this module
- RenamedHsBinds, -- Supporting bindings for derived instances
- FreeVars) -- And the free vars of the derived code
+ RenamedHsBinds) -- Supporting bindings for derived instances
tcInstDecls1 tycl_decls inst_decls
= checkNoErrs $
-- Stop if addInstInfos etc discovers any errors
-- (they recover, so that we get more than one error each round)
- let
- (src_inst_decls, iface_inst_decls) = partition isSourceInstDecl inst_decls
- in
-
- -- (0) Deal with the imported instance decls
- tcIfaceInstDecls iface_inst_decls `thenM` \ imp_dfuns ->
- tcExtendInstEnv imp_dfuns $
-- (1) Do the ordinary instance declarations
- mappM tcLocalInstDecl1 src_inst_decls `thenM` \ local_inst_infos ->
+ mappM tcLocalInstDecl1 inst_decls `thenM` \ local_inst_infos ->
let
local_inst_info = catMaybes local_inst_infos
getGenericInstances clas_decls `thenM` \ generic_inst_info ->
-- Next, construct the instance environment so far, consisting of
- -- a) imported instance decls (from this module)
- -- b) local instance decls
- -- c) generic instances
- tcExtendLocalInstEnv local_inst_info $
- tcExtendLocalInstEnv generic_inst_info $
+ -- a) local instance decls
+ -- b) generic instances
+ addInsts local_inst_info $
+ addInsts generic_inst_info $
-- (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 tycl_decls `thenM` \ (deriv_inst_info, deriv_binds, fvs) ->
- tcExtendLocalInstEnv deriv_inst_info $
+ tcDeriving tycl_decls `thenM` \ (deriv_inst_info, deriv_binds, keep_alive) ->
+ addInsts deriv_inst_info $
- getGblEnv `thenM` \ gbl_env ->
- returnM (gbl_env,
+ getGblEnv `thenM` \ gbl_env ->
+ returnM (gbl_env { tcg_keep = tcg_keep gbl_env `unionNameSets` keep_alive },
generic_inst_info ++ deriv_inst_info ++ local_inst_info,
- deriv_binds, fvs)
+ deriv_binds)
+
+addInsts :: [InstInfo] -> TcM a -> TcM a
+addInsts infos thing_inside
+ = tcExtendLocalInstEnv (map iDFunId infos) thing_inside
\end{code}
\begin{code}
-- Imported ones should have been checked already, and may indeed
-- contain something illegal in normal Haskell, notably
-- instance CCallable [Char]
-tcLocalInstDecl1 decl@(InstDecl poly_ty binds uprags Nothing src_loc)
+tcLocalInstDecl1 decl@(InstDecl poly_ty binds uprags src_loc)
= -- Prime error recovery, set source location
recoverM (returnM Nothing) $
addSrcLoc src_loc $
- addErrCtxt (instDeclCtxt poly_ty) $
+ addErrCtxt (instDeclCtxt1 poly_ty) $
-- Typecheck the instance type itself. We can't use
-- tcHsSigType, because it's not a valid user type.
- kcHsSigType poly_ty `thenM_`
- tcHsType poly_ty `thenM` \ poly_ty' ->
+ kcHsSigType poly_ty `thenM` \ kinded_ty ->
+ tcHsKindedType kinded_ty `thenM` \ poly_ty' ->
let
(tyvars, theta, tau) = tcSplitSigmaTy poly_ty'
in
msg = parens (ptext SLIT("the instance types do not agree with the functional dependencies of the class"))
\end{code}
-Imported instance declarations
-
-\begin{code}
-tcIfaceInstDecls :: [RenamedInstDecl] -> TcM [DFunId]
--- Deal with the instance decls,
-tcIfaceInstDecls decls = mappM tcIfaceInstDecl decls
-
-tcIfaceInstDecl :: RenamedInstDecl -> TcM DFunId
- -- An interface-file instance declaration
- -- Should be in scope by now, because we should
- -- have sucked in its interface-file definition
- -- So it will be replete with its unfolding etc
-tcIfaceInstDecl decl@(InstDecl poly_ty binds uprags (Just dfun_name) src_loc)
- = tcLookupGlobalId dfun_name
-\end{code}
-
-
-%************************************************************************
-%* *
-\subsection{Extracting generic instance declaration from class declarations}
-%* *
-%************************************************************************
-
-@getGenericInstances@ extracts the generic instance declarations from a class
-declaration. For exmaple
-
- class C a where
- op :: a -> a
-
- op{ x+y } (Inl v) = ...
- op{ x+y } (Inr v) = ...
- op{ x*y } (v :*: w) = ...
- op{ 1 } Unit = ...
-
-gives rise to the instance declarations
-
- instance C (x+y) where
- op (Inl v) = ...
- op (Inr v) = ...
-
- instance C (x*y) where
- op (v :*: w) = ...
-
- instance C 1 where
- op Unit = ...
-
-
-\begin{code}
-getGenericInstances :: [RenamedTyClDecl] -> TcM [InstInfo]
-getGenericInstances class_decls
- = mappM get_generics class_decls `thenM` \ gen_inst_infos ->
- let
- gen_inst_info = concat gen_inst_infos
- in
- if null gen_inst_info then
- returnM []
- else
- getDOpts `thenM` \ dflags ->
- ioToTcRn (dumpIfSet_dyn dflags Opt_D_dump_deriv "Generic instances"
- (vcat (map pprInstInfo gen_inst_info)))
- `thenM_`
- returnM gen_inst_info
-
-get_generics decl@(ClassDecl {tcdMeths = Nothing})
- = returnM [] -- Imported class decls
-
-get_generics decl@(ClassDecl {tcdName = class_name, tcdMeths = Just def_methods, tcdLoc = loc})
- | null groups
- = returnM [] -- The comon case: no generic default methods
-
- | otherwise -- A source class decl with generic default methods
- = recoverM (returnM []) $
- tcAddDeclCtxt decl $
- tcLookupClass class_name `thenM` \ clas ->
-
- -- Make an InstInfo out of each group
- mappM (mkGenericInstance clas loc) groups `thenM` \ inst_infos ->
-
- -- Check that there is only one InstInfo for each type constructor
- -- The main way this can fail is if you write
- -- f {| a+b |} ... = ...
- -- f {| x+y |} ... = ...
- -- Then at this point we'll have an InstInfo for each
- let
- tc_inst_infos :: [(TyCon, InstInfo)]
- tc_inst_infos = [(simpleInstInfoTyCon i, i) | i <- inst_infos]
-
- bad_groups = [group | group <- equivClassesByUniq get_uniq tc_inst_infos,
- group `lengthExceeds` 1]
- get_uniq (tc,_) = getUnique tc
- in
- mappM (addErrTc . dupGenericInsts) bad_groups `thenM_`
-
- -- Check that there is an InstInfo for each generic type constructor
- let
- missing = genericTyCons `minusList` [tc | (tc,_) <- tc_inst_infos]
- in
- checkTc (null missing) (missingGenericInstances missing) `thenM_`
-
- returnM inst_infos
-
- where
- -- Group the declarations by type pattern
- groups :: [(RenamedHsType, RenamedMonoBinds)]
- groups = assocElts (getGenericBinds def_methods)
-
-
----------------------------------
-getGenericBinds :: RenamedMonoBinds -> Assoc RenamedHsType RenamedMonoBinds
- -- Takes a group of method bindings, finds the generic ones, and returns
- -- them in finite map indexed by the type parameter in the definition.
-
-getGenericBinds EmptyMonoBinds = emptyAssoc
-getGenericBinds (AndMonoBinds m1 m2)
- = plusAssoc_C AndMonoBinds (getGenericBinds m1) (getGenericBinds m2)
-
-getGenericBinds (FunMonoBind id infixop matches loc)
- = mapAssoc wrap (foldl add emptyAssoc matches)
- -- Using foldl not foldr is vital, else
- -- we reverse the order of the bindings!
- where
- add env match = case maybeGenericMatch match of
- Nothing -> env
- Just (ty, match') -> extendAssoc_C (++) env (ty, [match'])
-
- wrap ms = FunMonoBind id infixop ms loc
-
----------------------------------
-mkGenericInstance :: Class -> SrcLoc
- -> (RenamedHsType, RenamedMonoBinds)
- -> TcM InstInfo
-
-mkGenericInstance clas loc (hs_ty, binds)
- -- Make a generic instance declaration
- -- For example: instance (C a, C b) => C (a+b) where { binds }
-
- = -- Extract the universally quantified type variables
- let
- sig_tvs = map UserTyVar (nameSetToList (extractHsTyVars hs_ty))
- in
- tcHsTyVars sig_tvs (kcHsSigType hs_ty) $ \ tyvars ->
-
- -- Type-check the instance type, and check its form
- tcHsSigType GenPatCtxt hs_ty `thenM` \ inst_ty ->
- checkTc (validGenericInstanceType inst_ty)
- (badGenericInstanceType binds) `thenM_`
-
- -- Make the dictionary function.
- newDFunName clas [inst_ty] loc `thenM` \ dfun_name ->
- let
- inst_theta = [mkClassPred clas [mkTyVarTy tv] | tv <- tyvars]
- dfun_id = mkDictFunId dfun_name tyvars inst_theta clas [inst_ty]
- in
-
- returnM (InstInfo { iDFunId = dfun_id, iBinds = VanillaInst binds [] })
-\end{code}
-
%************************************************************************
%* *
%************************************************************************
\begin{code}
-tcInstDecls2 :: [InstInfo] -> TcM TcMonoBinds
-tcInstDecls2 inst_decls
- = mappM tcInstDecl2 inst_decls `thenM` \ binds_s ->
- returnM (andMonoBindList binds_s)
+tcInstDecls2 :: [RenamedTyClDecl] -> [InstInfo]
+ -> TcM (TcLclEnv, TcMonoBinds)
+-- (a) From each class declaration,
+-- generate any default-method bindings
+-- (b) From each instance decl
+-- generate the dfun binding
+
+tcInstDecls2 tycl_decls inst_decls
+ = do { -- (a) Default methods from class decls
+ (dm_binds_s, dm_ids_s) <- mapAndUnzipM tcClassDecl2 $
+ filter isClassDecl tycl_decls
+ ; tcExtendLocalValEnv (concat dm_ids_s) $ do
+
+ -- (b) instance declarations
+ ; inst_binds_s <- mappM tcInstDecl2 inst_decls
+
+ -- Done
+ ; tcl_env <- getLclEnv
+ ; returnM (tcl_env, andMonoBindList dm_binds_s `AndMonoBinds`
+ andMonoBindList inst_binds_s) }
\end{code}
======= New documentation starts here (Sept 92) ==============
tcInstDecl2 (InstInfo { iDFunId = dfun_id, iBinds = binds })
= -- Prime error recovery
- recoverM (returnM EmptyMonoBinds) $
- addSrcLoc (getSrcLoc dfun_id) $
- addErrCtxt (instDeclCtxt (toHsType (idType dfun_id))) $
+ recoverM (returnM EmptyMonoBinds) $
+ addSrcLoc (getSrcLoc dfun_id) $
+ addErrCtxt (instDeclCtxt2 (idType dfun_id)) $
let
- inst_ty = idType dfun_id
+ inst_ty = idType dfun_id
(inst_tyvars, _) = tcSplitForAllTys inst_ty
-- The tyvars of the instance decl scope over the 'where' part
-- Those tyvars are inside the dfun_id's type, which is a bit
%************************************************************************
\begin{code}
-tcAddDeclCtxt decl thing_inside
- = addSrcLoc (tcdLoc decl) $
- addErrCtxt ctxt $
- thing_inside
+instDeclCtxt1 hs_inst_ty
+ = inst_decl_ctxt (case hs_inst_ty of
+ HsForAllTy _ _ _ (HsPredTy pred) -> ppr pred
+ HsPredTy pred -> ppr pred
+ other -> ppr hs_inst_ty) -- Don't expect this
+instDeclCtxt2 dfun_ty
+ = inst_decl_ctxt (ppr (mkClassPred cls tys))
where
- thing = case decl of
- ClassDecl {} -> "class"
- TySynonym {} -> "type synonym"
- TyData {tcdND = NewType} -> "newtype"
- TyData {tcdND = DataType} -> "data type"
-
- ctxt = hsep [ptext SLIT("In the"), text thing,
- ptext SLIT("declaration for"), quotes (ppr (tcdName decl))]
-
-instDeclCtxt inst_ty = ptext SLIT("In the instance declaration for") <+> quotes doc
- where
- doc = case inst_ty of
- HsForAllTy _ _ (HsPredTy pred) -> ppr pred
- HsPredTy pred -> ppr pred
- other -> ppr inst_ty -- Don't expect this
-\end{code}
+ (_,_,cls,tys) = tcSplitDFunTy dfun_ty
+
+inst_decl_ctxt doc = ptext SLIT("In the instance declaration for") <+> quotes doc
-\begin{code}
-badGenericInstanceType binds
- = vcat [ptext SLIT("Illegal type pattern in the generic bindings"),
- nest 4 (ppr binds)]
-
-missingGenericInstances missing
- = ptext SLIT("Missing type patterns for") <+> pprQuotedList missing
-
-dupGenericInsts tc_inst_infos
- = vcat [ptext SLIT("More than one type pattern for a single generic type constructor:"),
- nest 4 (vcat (map ppr_inst_ty tc_inst_infos)),
- ptext SLIT("All the type patterns for a generic type constructor must be identical")
- ]
- where
- ppr_inst_ty (tc,inst) = ppr (simpleInstInfoTy inst)
-
-methodCtxt = ptext SLIT("When checking the methods of an instance declaration")
superClassCtxt = ptext SLIT("When checking the super-classes of an instance declaration")
\end{code}
projects / ghc-hetmet.git / blobdiff