The type annotation for `leftJoin` does not match its definition.

10│ leftJoin : Stream comparable v1 -> Stream comparable v2 -> Stream comparable (v1, Maybe v2)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The type annotation is saying:

    Signal ( comparable, a )
    -> Signal ( comparable, b )
    -> Signal ( comparable, ( a, Maybe b ) )

But I am inferring that the definition has this type:

    Signal ( comparable, a )
    -> Signal ( comparable, a )
    -> Signal ( comparable, ( a, Maybe b ) )