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authorRyan Scott <ryan.gl.scott@gmail.com>2017-10-27 22:10:27 -0700
committerAlexander Biehl <alexbiehl@gmail.com>2017-10-28 07:10:27 +0200
commit3896bff411596ef50b5ca2f2be425e89878410aa (patch)
tree6ed6272052e5ad006ab3fe5d841d40815bcd68f4 /haddock-api
parentd4375d8ec96991de2578fd65c79d0487f6a440d8 (diff)
Fix Haddock rendering of kind-indexed data family instances (#694)
Diffstat (limited to 'haddock-api')
-rw-r--r--haddock-api/src/Haddock/Convert.hs28
1 files changed, 23 insertions, 5 deletions
diff --git a/haddock-api/src/Haddock/Convert.hs b/haddock-api/src/Haddock/Convert.hs
index 325d9cf6..96a08555 100644
--- a/haddock-api/src/Haddock/Convert.hs
+++ b/haddock-api/src/Haddock/Convert.hs
@@ -41,7 +41,8 @@ import TysWiredIn ( listTyConName, starKindTyConName, unitTy )
import PrelNames ( hasKey, eqTyConKey, funTyConKey, ipClassKey
, tYPETyConKey, liftedRepDataConKey )
import Unique ( getUnique )
-import Util ( compareLength, filterByList, filterOut, splitAtList )
+import Util ( chkAppend, compareLength, dropList, filterByList, filterOut
+ , splitAtList )
import Var
import VarSet
@@ -543,7 +544,7 @@ synifyInstHead (_, preds, cls, types) = specializeInstHead $ InstHead
-- Convert a family instance, this could be a type family or data family
synifyFamInst :: FamInst -> Bool -> Either ErrMsg (InstHead GhcRn)
synifyFamInst fi opaque = do
- ityp' <- ityp $ fi_flavor fi
+ ityp' <- ityp fam_flavor
return InstHead
{ ihdClsName = fi_fam fi
, ihdTypes = map unLoc annot_ts
@@ -552,11 +553,28 @@ synifyFamInst fi opaque = do
where
ityp SynFamilyInst | opaque = return $ TypeInst Nothing
ityp SynFamilyInst =
- return . TypeInst . Just . unLoc . synifyType WithinType $ fi_rhs fi
+ return . TypeInst . Just . unLoc $ synifyType WithinType fam_rhs
ityp (DataFamilyInst c) =
DataInst <$> synifyTyCon (Just $ famInstAxiom fi) c
- fam_tc = famInstTyCon fi
- ts = filterOutInvisibleTypes fam_tc $ fi_tys fi
+ fam_tc = famInstTyCon fi
+ fam_flavor = fi_flavor fi
+ fam_lhs = fi_tys fi
+ fam_rhs = fi_rhs fi
+
+ eta_expanded_lhs
+ -- eta-expand lhs types, because sometimes data/newtype
+ -- instances are eta-reduced; See Trac #9692
+ -- See Note [Eta reduction for data family axioms] in TcInstDcls in GHC
+ | DataFamilyInst rep_tc <- fam_flavor
+ = let (_, rep_tc_args) = splitTyConApp fam_rhs
+ etad_tyvars = dropList rep_tc_args $ tyConTyVars rep_tc
+ etad_tys = mkTyVarTys etad_tyvars
+ eta_exp_lhs = fam_lhs `chkAppend` etad_tys
+ in eta_exp_lhs
+ | otherwise
+ = fam_lhs
+
+ ts = filterOutInvisibleTypes fam_tc eta_expanded_lhs
synifyTypes = map (synifyType WithinType)
ts' = synifyTypes ts
annot_ts = zipWith3 annotHsType is_poly_tvs ts ts'