message: fixed ts typecheck
diff: @@ -128,7 +128,7 @@ namespace Column {
  }
  export function mapToArray<T, S>(column: Column<T>, f: (v: T) => S, ctor?: ArrayCtor<S>): ArrayLike<S> {
  - return mapToArrayImpl(column, f, ctor || Array);
  + return mapToArrayImpl<T, S>(column, f, ctor || Array);
  }
  export function areEqual<T>(a: Column<T>, b: Column<T>) {
  