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-rw-r--r--haddock-api/src/Haddock/Interface/Specialize.hs20
1 files changed, 10 insertions, 10 deletions
diff --git a/haddock-api/src/Haddock/Interface/Specialize.hs b/haddock-api/src/Haddock/Interface/Specialize.hs
index 092a2f4e..2fcb495c 100644
--- a/haddock-api/src/Haddock/Interface/Specialize.hs
+++ b/haddock-api/src/Haddock/Interface/Specialize.hs
@@ -29,23 +29,23 @@ import qualified Data.Set as Set
-- | Instantiate all occurrences of given names with corresponding types.
specialize :: Data a => [(Name, HsType GhcRn)] -> a -> a
-specialize specs = go
+specialize specs = go spec_map0
where
- go :: forall x. Data x => x -> x
- go = everywhereButType @Name $ mkT $ sugar . strip_kind_sig . specialize_ty_var
+ go :: forall x. Data x => Map Name (HsType GhcRn) -> x -> x
+ go spec_map = everywhereButType @Name $ mkT $ sugar . strip_kind_sig . specialize_ty_var spec_map
strip_kind_sig :: HsType name -> HsType name
strip_kind_sig (HsKindSig _ (L _ t) _) = t
strip_kind_sig typ = typ
- specialize_ty_var :: HsType GhcRn -> HsType GhcRn
- specialize_ty_var (HsTyVar _ _ (L _ name'))
+ specialize_ty_var :: Map Name (HsType GhcRn) -> HsType GhcRn -> HsType GhcRn
+ specialize_ty_var spec_map (HsTyVar _ _ (L _ name'))
| Just t <- Map.lookup name' spec_map = t
- specialize_ty_var typ = typ
- -- This is a tricky recursive definition that is guaranteed to terminate
- -- because a type binder cannot be instantiated with a type that depends
- -- on that binder. i.e. @a -> Maybe a@ is invalid
- spec_map = Map.fromList [ (n, go t) | (n, t) <- specs]
+ specialize_ty_var _ typ = typ
+
+ -- This is a tricky recursive definition. By adding in the specializations
+ -- one by one, we should avoid infinite loops.
+ spec_map0 = foldr (\(n,t) acc -> Map.insert n (go acc t) acc) mempty specs
-- | Instantiate given binders with corresponding types.