-\section[FamInst]{The @FamInst@ type: family instance heads}
+The @FamInst@ type: family instance heads
\begin{code}
module FamInst (
#include "HsVersions.h"
-import FamInstEnv ( FamInstEnv, FamInst(..), famInstTyCon, extendFamInstEnv,
- pprFamInst, pprFamInsts )
-import TcMType ( tcInstSkolType )
-import TcType ( SkolemInfo(..), tcSplitTyConApp )
-import TcRnMonad ( TcM, TcGblEnv(..), setGblEnv, getGblEnv, foldlM,
- setSrcSpan, addErr )
-import TyCon ( tyConFamInst_maybe )
-import Type ( mkTyConApp )
-import Name ( getSrcLoc )
-import SrcLoc ( mkSrcSpan )
+import HscTypes
+import FamInstEnv
+import TcMType
+import TcType
+import TcRnMonad
+import TyCon
+import Type
import Outputable
\end{code}
tcExtendLocalFamInstEnv fam_insts thing_inside
= do { env <- getGblEnv
; inst_env' <- foldlM addLocalFamInst (tcg_fam_inst_env env) fam_insts
- ; let env' = env { tcg_fam_inst_env = inst_env' }
+ ; let env' = env { tcg_fam_insts = fam_insts ++ tcg_fam_insts env,
+ tcg_fam_inst_env = inst_env' }
; setGblEnv env' thing_inside }
-- and then add it to the home inst env
addLocalFamInst :: FamInstEnv -> FamInst -> TcM FamInstEnv
addLocalFamInst home_fie famInst
- = do { -- Instantiate the family instance type extend the instance
+ = do { -- To instantiate the family instance type, extend the instance
-- envt with completely fresh template variables
-- This is important because the template variables must
-- not overlap with anything in the things being looked up
; let (fam, tys') = tcSplitTyConApp tau'
-{- !!!TODO: Need to complete this:
-- Load imported instances, so that we report
-- overlaps correctly
; eps <- getEps
; let inst_envs = (eps_fam_inst_env eps, home_fie)
+{- !!!TODO: Need to complete this:
-- Check for overlapping instance decls
; let { (matches, _) = lookupFamInstEnv inst_envs fam tys'
; dup_ispecs = [ dup_ispec --!!!adapt
-- OK, now extend the envt
; return (extendFamInstEnv home_fie famInst) }
+{- UNUSED??? --SDM
overlapErr famInst dupFamInst
= addFamInstLoc famInst $
addErr (hang (ptext SLIT("Overlapping family instance declarations:"))
= setSrcSpan (mkSrcSpan loc loc) thing_inside
where
loc = getSrcLoc famInst
+-}
\end{code}