Add dataCast1 definition for HashMap

Author: treeowl

CHANGES.md

@@ -1,3 +1,7 @@
+## [0.2.17.0]
+
+* Define `dataCast1` for `HashMap`.
+
 ## [0.2.16.0]
 
 * [Increase maximum branching factor from 16 to 32](https://github.com/haskell-unordered-containers/unordered-containers/pull/317)

Data/HashMap/Internal.hs

@@ -303,6 +303,7 @@ instance (Data k, Data v, Eq k, Hashable k) => Data (HashMap k v) where
         1 -> k (z fromList)
         _ -> error "gunfold"
     dataTypeOf _   = hashMapDataType
+    dataCast1 f    = gcast1 f
     dataCast2 f    = gcast2 f
 
 fromListConstr :: Constr