[MLton-user] Extended Basis Library: Partial order concept

Vesa Karvonen vesa.a.j.k at gmail.com
Tue May 8 08:43:31 PDT 2007

On 5/8/07, Geoffrey Alan Washburn <geoffw at cis.upenn.edu> wrote:
>      While shorter is usually better, I'm not sure I agree in this case.  At
> least I hypothesize that most times that someone would want to define a
> partial order, they would find it more natural to define it in terms of a
> reflexive, transitive, anti-symmetric relation, rather than a transitive,
> anti-symmetric relation.  For example, in one of my several structures that
> admits a partial order (but not a total order) is an ordering based upon
> subset inclusion.  Therefore, I could define
>      val op <= = Set.isSubset
>  instead of
>      fun x < y = Set.isSubset (x, y) andalso not (Set.==(x, y))
>  furthermore in some cases equality will be defined in terms of <= and
> therefore writing something like the above may be a little awkward.

Those are good points and I have to agree that <= is probably the better
alternative for the partial order concept.  Indeed, the table in my previous
message doesn't apply to this case.  I apparently made it under the
assumption of a total order.

-Vesa Karvonen

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