tcLookupLocatedGlobal, tcLookupGlobal,
tcLookupField, tcLookupTyCon, tcLookupClass, tcLookupDataCon,
tcLookupLocatedGlobalId, tcLookupLocatedTyCon,
- tcLookupLocatedClass, tcLookupFamInst,
+ tcLookupLocatedClass,
+ tcLookupFamInst, tcLookupDataFamInst,
-- Local environment
tcExtendKindEnv, tcExtendKindEnvTvs,
tcExtendIdEnv, tcExtendIdEnv1, tcExtendIdEnv2,
tcLookup, tcLookupLocated, tcLookupLocalIds,
tcLookupId, tcLookupTyVar, getScopedTyVarBinds,
- lclEnvElts, getInLocalScope, findGlobals,
+ getInLocalScope,
wrongThingErr, pprBinders,
+ getHetMetLevel,
tcExtendRecEnv, -- For knot-tying
-- Rules
tcExtendRules,
+ -- Defaults
+ tcGetDefaultTys,
+
-- Global type variables
tcGetGlobalTyVars,
#include "HsVersions.h"
import HsSyn
-import TcIface
import IfaceEnv
import TcRnMonad
import TcMType
import TcType
--- import TcSuspension
-import qualified Type
+import TcIface
+import PrelNames
+import TysWiredIn
+-- import qualified Type
import Id
import Coercion
import Var
import VarSet
-import VarEnv
+-- import VarEnv
import RdrName
import InstEnv
import FamInstEnv
import Name
import NameEnv
import HscTypes
+import DynFlags
import SrcLoc
import Outputable
import Unique
-- Should it have been in the local envt?
{ case nameModule_maybe name of
- Nothing -> notFound name env -- Internal names can happen in GHCi
+ Nothing -> notFound name -- Internal names can happen in GHCi
Just mod | mod == tcg_mod env -- Names from this module
- -> notFound name env -- should be in tcg_type_env
+ -> notFound name -- should be in tcg_type_env
| otherwise
-> tcImportDecl name -- Go find it in an interface
}}}}}
--
tcLookupFamInst :: TyCon -> [Type] -> TcM (Maybe (TyCon, [Type]))
tcLookupFamInst tycon tys
- | not (isOpenTyCon tycon)
+ | not (isFamilyTyCon tycon)
= return Nothing
| otherwise
= do { env <- getGblEnv
; eps <- getEps
; let instEnv = (eps_fam_inst_env eps, tcg_fam_inst_env env)
+ ; traceTc "lookupFamInst" ((ppr tycon <+> ppr tys) $$ ppr instEnv)
; case lookupFamInstEnv instEnv tycon tys of
[] -> return Nothing
((fam_inst, rep_tys):_)
-> return $ Just (famInstTyCon fam_inst, rep_tys)
}
+
+tcLookupDataFamInst :: TyCon -> [Type] -> TcM (TyCon, [Type])
+-- Find the instance of a data family
+-- Note [Looking up family instances for deriving]
+tcLookupDataFamInst tycon tys
+ | not (isFamilyTyCon tycon)
+ = return (tycon, tys)
+ | otherwise
+ = ASSERT( isAlgTyCon tycon )
+ do { maybeFamInst <- tcLookupFamInst tycon tys
+ ; case maybeFamInst of
+ Nothing -> famInstNotFound tycon tys
+ Just famInst -> return famInst }
+
+famInstNotFound :: TyCon -> [Type] -> TcM a
+famInstNotFound tycon tys
+ = failWithTc (ptext (sLit "No family instance for")
+ <+> quotes (pprTypeApp tycon tys))
\end{code}
+Note [Looking up family instances for deriving]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+tcLookupFamInstExact is an auxiliary lookup wrapper which requires
+that looked-up family instances exist. If called with a vanilla
+tycon, the old type application is simply returned.
+
+If we have
+ data instance F () = ... deriving Eq
+ data instance F () = ... deriving Eq
+then tcLookupFamInstExact will be confused by the two matches;
+but that can't happen because tcInstDecls1 doesn't call tcDeriving
+if there are any overlaps.
+
+There are two other things that might go wrong with the lookup.
+First, we might see a standalone deriving clause
+ deriving Eq (F ())
+when there is no data instance F () in scope.
+
+Note that it's OK to have
+ data instance F [a] = ...
+ deriving Eq (F [(a,b)])
+where the match is not exact; the same holds for ordinary data types
+with standalone deriving declrations.
+
\begin{code}
instance MonadThings (IOEnv (Env TcGblEnv TcLclEnv)) where
lookupThing = tcLookupGlobal
tcLookup :: Name -> TcM TcTyThing
tcLookup name = do
- local_env <- getLclEnv
- case lookupNameEnv (tcl_env local_env) name of
+ local_env <- getLclTypeEnv
+ case lookupNameEnv local_env name of
Just thing -> return thing
Nothing -> AGlobal <$> tcLookupGlobal name
-> ASSERT( lvl == lvl1 ) id
_ -> pprPanic "tcLookupLocalIds" (ppr name)
-lclEnvElts :: TcLclEnv -> [TcTyThing]
-lclEnvElts env = nameEnvElts (tcl_env env)
-
getInLocalScope :: TcM (Name -> Bool)
-- Ids only
-getInLocalScope = do
- env <- getLclEnv
- let lcl_env = tcl_env env
- return (`elemNameEnv` lcl_env)
+getInLocalScope = do { lcl_env <- getLclTypeEnv
+ ; return (`elemNameEnv` lcl_env) }
\end{code}
\begin{code}
upd lcl_env = lcl_env { tcl_env = extend (tcl_env lcl_env) }
extend env = extendNameEnvList env [(n, AThing k) | (n,k) <- things]
-tcExtendKindEnvTvs :: [LHsTyVarBndr Name] -> TcM r -> TcM r
+tcExtendKindEnvTvs :: [LHsTyVarBndr Name] -> ([LHsTyVarBndr Name] -> TcM r) -> TcM r
tcExtendKindEnvTvs bndrs thing_inside
- = updLclEnv upd thing_inside
- where
- upd lcl_env = lcl_env { tcl_env = extend (tcl_env lcl_env) }
- extend env = extendNameEnvList env pairs
- pairs = [(n, AThing k) | L _ (KindedTyVar n k) <- bndrs]
+ = tcExtendKindEnv (map (hsTyVarNameKind . unLoc) bndrs)
+ (thing_inside bndrs)
tcExtendTyVarEnv :: [TyVar] -> TcM r -> TcM r
tcExtendTyVarEnv tvs thing_inside
-- Here, g mustn't be generalised. This is also important during
-- class and instance decls, when we mustn't generalise the class tyvars
-- when typechecking the methods.
- gtvs' <- tc_extend_gtvs gtvs new_tv_set
+ gtvs' <- tcExtendGlobalTyVars gtvs new_tv_set
setLclEnv (env {tcl_env = le', tcl_tyvars = gtvs', tcl_rdr = rdr_env'}) thing_inside
getScopedTyVarBinds :: TcM [(Name, TcType)]
tcExtendIdEnv1 :: Name -> TcId -> TcM a -> TcM a
tcExtendIdEnv1 name id thing_inside = tcExtendIdEnv2 [(name,id)] thing_inside
+getHetMetLevel :: TcM [TyVar]
+getHetMetLevel =
+ do { env <- getEnv
+ ; return $ case env of Env { env_lcl = e' } -> case e' of TcLclEnv { tcl_hetMetLevel = x } -> x
+ }
+
tcExtendIdEnv2 :: [(Name,TcId)] -> TcM a -> TcM a
-- Invariant: the TcIds are fully zonked (see tcExtendIdEnv above)
tcExtendIdEnv2 names_w_ids thing_inside
= do { env <- getLclEnv
- ; tc_extend_local_id_env env (thLevel (tcl_th_ctxt env)) names_w_ids thing_inside }
+ ; hetMetLevel <- getHetMetLevel
+ ; tc_extend_local_id_env env (thLevel (tcl_th_ctxt env)) hetMetLevel names_w_ids thing_inside }
+
tcExtendGhciEnv :: [TcId] -> TcM a -> TcM a
-- Used to bind Ids for GHCi identifiers bound earlier in the user interaction
-- GHCi has already compiled it to bytecode
tcExtendGhciEnv ids thing_inside
= do { env <- getLclEnv
- ; tc_extend_local_id_env env impLevel [(idName id, id) | id <- ids] thing_inside }
+ ; hetMetLevel <- getHetMetLevel
+ ; tc_extend_local_id_env env impLevel hetMetLevel [(idName id, id) | id <- ids] thing_inside }
tc_extend_local_id_env -- This is the guy who does the work
:: TcLclEnv
-> ThLevel
+ -> [TyVar]
-> [(Name,TcId)]
-> TcM a -> TcM a
-- Invariant: the TcIds are fully zonked. Reasons:
-- in the types, because instantiation does not look through such things
-- (c) The call to tyVarsOfTypes is ok without looking through refs
-tc_extend_local_id_env env th_lvl names_w_ids thing_inside
- = do { traceTc (text "env2")
- ; traceTc (text "env3" <+> ppr extra_env)
- ; gtvs' <- tc_extend_gtvs (tcl_tyvars env) extra_global_tyvars
+tc_extend_local_id_env env th_lvl hetMetLevel names_w_ids thing_inside
+ = do { traceTc "env2" (ppr extra_env)
+ ; gtvs' <- tcExtendGlobalTyVars (tcl_tyvars env) extra_global_tyvars
; let env' = env {tcl_env = le', tcl_tyvars = gtvs', tcl_rdr = rdr_env'}
; setLclEnv env' thing_inside }
where
extra_global_tyvars = tcTyVarsOfTypes [idType id | (_,id) <- names_w_ids]
extra_env = [ (name, ATcId { tct_id = id,
tct_level = th_lvl,
- tct_type = id_ty,
- tct_co = case isRefineableTy id_ty of
- (True,_) -> Unrefineable
- (_,True) -> Rigid idHsWrapper
- _ -> Wobbly})
- | (name,id) <- names_w_ids, let id_ty = idType id]
+ tct_hetMetLevel = hetMetLevel
+ })
+ | (name,id) <- names_w_ids]
le' = extendNameEnvList (tcl_env env) extra_env
rdr_env' = extendLocalRdrEnvList (tcl_rdr env) [name | (name,_) <- names_w_ids]
-\end{code}
-
-\begin{code}
------------------------
--- findGlobals looks at the value environment and finds values
--- whose types mention the offending type variable. It has to be
--- careful to zonk the Id's type first, so it has to be in the monad.
--- We must be careful to pass it a zonked type variable, too.
-
-findGlobals :: TcTyVarSet
- -> TidyEnv
- -> TcM (TidyEnv, [SDoc])
-
-findGlobals tvs tidy_env = do
- lcl_env <- getLclEnv
- go tidy_env [] (lclEnvElts lcl_env)
- where
- go tidy_env acc [] = return (tidy_env, acc)
- go tidy_env acc (thing : things) = do
- (tidy_env1, maybe_doc) <- find_thing ignore_it tidy_env thing
- case maybe_doc of
- Just d -> go tidy_env1 (d:acc) things
- Nothing -> go tidy_env1 acc things
-
- ignore_it ty = tvs `disjointVarSet` tyVarsOfType ty
-
------------------------
-find_thing :: (TcType -> Bool) -> TidyEnv -> TcTyThing
- -> TcM (TidyEnv, Maybe SDoc)
-find_thing ignore_it tidy_env (ATcId { tct_id = id }) = do
- id_ty <- zonkTcType (idType id)
- if ignore_it id_ty then
- return (tidy_env, Nothing)
- else let
- (tidy_env', tidy_ty) = tidyOpenType tidy_env id_ty
- msg = sep [ppr id <+> dcolon <+> ppr tidy_ty,
- nest 2 (parens (ptext (sLit "bound at") <+>
- ppr (getSrcLoc id)))]
- in
- return (tidy_env', Just msg)
-
-find_thing ignore_it tidy_env (ATyVar tv ty) = do
- tv_ty <- zonkTcType ty
- if ignore_it tv_ty then
- return (tidy_env, Nothing)
- else let
- -- The name tv is scoped, so we don't need to tidy it
- (tidy_env1, tidy_ty) = tidyOpenType tidy_env tv_ty
- msg = sep [ptext (sLit "Scoped type variable") <+> quotes (ppr tv) <+> eq_stuff, nest 2 bound_at]
-
- eq_stuff | Just tv' <- Type.getTyVar_maybe tv_ty,
- getOccName tv == getOccName tv' = empty
- | otherwise = equals <+> ppr tidy_ty
- -- It's ok to use Type.getTyVar_maybe because ty is zonked by now
- bound_at = parens $ ptext (sLit "bound at:") <+> ppr (getSrcLoc tv)
- in
- return (tidy_env1, Just msg)
-
-find_thing _ _ thing = pprPanic "find_thing" (ppr thing)
-\end{code}
-
-%************************************************************************
-%* *
-\subsection{The global tyvars}
-%* *
-%************************************************************************
-
-\begin{code}
-tc_extend_gtvs :: IORef VarSet -> VarSet -> TcM (IORef VarSet)
-tc_extend_gtvs gtvs extra_global_tvs = do
- global_tvs <- readMutVar gtvs
- newMutVar (global_tvs `unionVarSet` extra_global_tvs)
-\end{code}
-
-@tcGetGlobalTyVars@ returns a fully-zonked set of tyvars free in the environment.
-To improve subsequent calls to the same function it writes the zonked set back into
-the environment.
-
-\begin{code}
-tcGetGlobalTyVars :: TcM TcTyVarSet
-tcGetGlobalTyVars = do
- (TcLclEnv {tcl_tyvars = gtv_var}) <- getLclEnv
- gbl_tvs <- readMutVar gtv_var
- gbl_tvs' <- zonkTcTyVarsAndFV (varSetElems gbl_tvs)
- writeMutVar gtv_var gbl_tvs'
- return gbl_tvs'
+tcExtendGlobalTyVars :: IORef VarSet -> VarSet -> TcM (IORef VarSet)
+tcExtendGlobalTyVars gtv_var extra_global_tvs
+ = do { global_tvs <- readMutVar gtv_var
+ ; newMutVar (global_tvs `unionVarSet` extra_global_tvs) }
\end{code}
\begin{code}
tcExtendRules :: [LRuleDecl Id] -> TcM a -> TcM a
-- Just pop the new rules into the EPS and envt resp
- -- All the rules come from an interface file, not soruce
+ -- All the rules come from an interface file, not source
-- Nevertheless, some may be for this module, if we read
-- its interface instead of its source code
tcExtendRules lcl_rules thing_inside
= failWithTc $
sep [ptext (sLit "GHC stage restriction:") <+> pp_thing,
nest 2 (vcat [ ptext (sLit "is used in a top-level splice or annotation,")
- , ptext (sLit ", and must be imported, not defined locally")])]
+ , ptext (sLit "and must be imported, not defined locally")])]
| otherwise -- Badly staged
= failWithTc $ -- E.g. \x -> $(f x)
%************************************************************************
%* *
+ getDefaultTys
+%* *
+%************************************************************************
+
+\begin{code}
+tcGetDefaultTys :: Bool -- True <=> interactive context
+ -> TcM ([Type], -- Default types
+ (Bool, -- True <=> Use overloaded strings
+ Bool)) -- True <=> Use extended defaulting rules
+tcGetDefaultTys interactive
+ = do { dflags <- getDOpts
+ ; let ovl_strings = xopt Opt_OverloadedStrings dflags
+ extended_defaults = interactive
+ || xopt Opt_ExtendedDefaultRules dflags
+ -- See also Trac #1974
+ flags = (ovl_strings, extended_defaults)
+
+ ; mb_defaults <- getDeclaredDefaultTys
+ ; case mb_defaults of {
+ Just tys -> return (tys, flags) ;
+ -- User-supplied defaults
+ Nothing -> do
+
+ -- No use-supplied default
+ -- Use [Integer, Double], plus modifications
+ { integer_ty <- tcMetaTy integerTyConName
+ ; checkWiredInTyCon doubleTyCon
+ ; string_ty <- tcMetaTy stringTyConName
+ ; let deflt_tys = opt_deflt extended_defaults unitTy -- Note [Default unitTy]
+ ++ [integer_ty, doubleTy]
+ ++ opt_deflt ovl_strings string_ty
+ ; return (deflt_tys, flags) } } }
+ where
+ opt_deflt True ty = [ty]
+ opt_deflt False _ = []
+\end{code}
+
+Note [Default unitTy]
+~~~~~~~~~~~~~~~~~~~~~
+In interative mode (or with -XExtendedDefaultRules) we add () as the first type we
+try when defaulting. This has very little real impact, except in the following case.
+Consider:
+ Text.Printf.printf "hello"
+This has type (forall a. IO a); it prints "hello", and returns 'undefined'. We don't
+want the GHCi repl loop to try to print that 'undefined'. The neatest thing is to
+default the 'a' to (), rather than to Integer (which is what would otherwise happen;
+and then GHCi doesn't attempt to print the (). So in interactive mode, we add
+() to the list of defaulting types. See Trac #1200.
+
+
+%************************************************************************
+%* *
\subsection{The InstInfo type}
%* *
%************************************************************************
\begin{code}
data InstInfo a
= InstInfo {
- iSpec :: Instance, -- Includes the dfun id. Its forall'd type
- iBinds :: InstBindings a -- variables scope over the stuff in InstBindings!
+ iSpec :: Instance, -- Includes the dfun id. Its forall'd type
+ iBinds :: InstBindings a -- variables scope over the stuff in InstBindings!
}
iDFunId :: InstInfo a -> DFunId
[LSig a] -- User pragmas recorded for generating
-- specialised instances
Bool -- True <=> This code came from a standalone deriving clause
+ -- Used only to improve error messages
+
+ | NewTypeDerived -- Used for deriving instances of newtypes, where the
+ -- witness dictionary is identical to the argument
+ -- dictionary. Hence no bindings, no pragmas.
+
+ Coercion -- The coercion maps from newtype to the representation type
+ -- (mentioning type variables bound by the forall'd iSpec variables)
+ -- E.g. newtype instance N [a] = N1 (Tree a)
+ -- co : N [a] ~ Tree a
- | NewTypeDerived -- Used for deriving instances of newtypes, where the
- CoercionI -- witness dictionary is identical to the argument
- -- dictionary. Hence no bindings, no pragmas.
- -- The coercion maps from newtype to the representation type
- -- (mentioning type variables bound by the forall'd iSpec variables)
- -- E.g. newtype instance N [a] = N1 (Tree a)
- -- co : N [a] ~ Tree a
+ TyCon -- The TyCon is the newtype N. If it's indexed, then it's the
+ -- representation TyCon, so that tyConDataCons returns [N1],
+ -- the "data constructor".
+ -- See Note [Newtype deriving and unused constructors]
+ -- in TcDeriv
pprInstInfo :: InstInfo a -> SDoc
-pprInstInfo info = vcat [ptext (sLit "InstInfo:") <+> ppr (idType (iDFunId info))]
+pprInstInfo info = hang (ptext (sLit "instance"))
+ 2 (sep [ ifPprDebug (pprForAll tvs)
+ , pprThetaArrowTy theta, ppr tau
+ , ptext (sLit "where")])
+ where
+ (tvs, theta, tau) = tcSplitSigmaTy (idType (iDFunId info))
+
pprInstInfoDetails :: OutputableBndr a => InstInfo a -> SDoc
pprInstInfoDetails info = pprInstInfo info $$ nest 2 (details (iBinds info))
where
details (VanillaInst b _ _) = pprLHsBinds b
- details (NewTypeDerived _) = text "Derived from the representation type"
+ details (NewTypeDerived {}) = text "Derived from the representation type"
simpleInstInfoClsTy :: InstInfo a -> (Class, Type)
simpleInstInfoClsTy info = case instanceHead (iSpec info) of
\end{code}
Make a name for the representation tycon of a family instance. It's an
-*external* name, like otber top-level names, and hence must be made with
+*external* name, like other top-level names, and hence must be made with
newGlobalBinder.
\begin{code}
pprBinders [bndr] = quotes (ppr bndr)
pprBinders bndrs = pprWithCommas ppr bndrs
-notFound :: Name -> TcGblEnv -> TcM TyThing
-notFound name env
- = failWithTc (vcat[ptext (sLit "GHC internal error:") <+> quotes (ppr name) <+>
+notFound :: Name -> TcM TyThing
+notFound name
+ = do { (gbl,lcl) <- getEnvs
+ ; failWithTc (vcat[ptext (sLit "GHC internal error:") <+> quotes (ppr name) <+>
ptext (sLit "is not in scope during type checking, but it passed the renamer"),
- ptext (sLit "tcg_type_env of environment:") <+> ppr (tcg_type_env env)]
- )
+ ptext (sLit "tcg_type_env of environment:") <+> ppr (tcg_type_env gbl),
+ ptext (sLit "tcl_env of environment:") <+> ppr (tcl_env lcl)]
+ ) }
wrongThingErr :: String -> TcTyThing -> Name -> TcM a
wrongThingErr expected thing name
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