[clean-list] Need help with trivial question: uswap :: A.a: Int Int *{*{a}} -> *{*{a}}

[vag]

YES!!! This is that I missed! replace! Huge thanks! This is exactly what 
I desire.
>
> uswap :: A.a: Int Int *{*{a}} -> *{*{a}}
> uswap i j a
>     # (ai, a) = replace a i undef
>       (aj, a) = replace a j ai
>       (_, a) = replace a i aj
>     = a
>
>
Kind regards,
Vag.