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

[John van Groningen]

lethevert wrote:
>How about this code?
>
>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

An update can be used instead of the last replace:

uswap :: !Int !Int !*{.a} -> *{.a}
uswap i j a
    # (ai, a) = replace a i undef
      (aj, a) = replace a j ai
    = {a & [i] = aj}

Kind regards,

John van Groningen