import TcType
import TcGadt
import qualified Type
-import Id
import Var
import VarSet
import VarEnv
; eps <- getEps
; let instEnv = (eps_fam_inst_env eps, tcg_fam_inst_env env)
; case lookupFamInstEnv instEnv tycon tys of
- [(subst,fam_inst)] -> return (rep_tc, substTyVars subst (tyConTyVars rep_tc))
+
+ [(subst, fam_inst)] | variable_only_subst ->
+ return (rep_tc, substTyVars subst (tyConTyVars rep_tc))
where -- NB: assumption is that (tyConTyVars rep_tc) is in
-- the domain of the substitution
- rep_tc = famInstTyCon fam_inst
+ rep_tc = famInstTyCon fam_inst
+ subst_domain = varEnvElts . getTvSubstEnv $ subst
+ tvs = map (Type.getTyVar "tcLookupFamInst")
+ subst_domain
+ variable_only_subst = all Type.isTyVarTy subst_domain &&
+ sizeVarSet (mkVarSet tvs) == length tvs
+ -- renaming may have no repetitions
other -> famInstNotFound tycon tys other
}
name, like otber top-level names, and hence must be made with newGlobalBinder.
\begin{code}
-newDFunName :: Class -> [Type] -> SrcLoc -> TcM Name
+newDFunName :: Class -> [Type] -> SrcSpan -> TcM Name
newDFunName clas (ty:_) loc
= do { index <- nextDFunIndex
; is_boot <- tcIsHsBoot
newDFunName clas [] loc = pprPanic "newDFunName" (ppr clas <+> ppr loc)
\end{code}
-Make a name for the representation tycon of a data/newtype instance. It's an
+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
newGlobalBinder.
\begin{code}
-newFamInstTyConName :: Name -> SrcLoc -> TcM Name
+newFamInstTyConName :: Name -> SrcSpan -> TcM Name
newFamInstTyConName tc_name loc
= do { index <- nextDFunIndex
; mod <- getModule
ptext SLIT("used as a") <+> text expected)
famInstNotFound tycon tys what
- = failWithTc (msg <+> quotes (ppr tycon <+> hsep (map pprParendType tys)))
+ = failWithTc (msg <+> quotes (pprTypeApp (ppr tycon) tys))
where
- msg = case what of
- [] -> ptext SLIT("No instance for")
- xs -> ptext SLIT("More than one instance for")
+ msg = ptext $ if length what > 1
+ then SLIT("More than one family instance for")
+ else SLIT("No family instance exactly matching")
\end{code}