append package:proto-lens

append :: forall m (v :: Type -> Type) a . (PrimMonad m, Vector v a) => Growing v (PrimState m) a -> a -> m (Growing v (PrimState m) a)

proto-lens Data.ProtoLens.Encoding.Growing

Returns a new growing vector with a new element at the end. Note that the return value may share storage with the input value. Furthermore, calling append twice on the same input may result in two vectors that share the same storage.