On Wed, Feb 03, 2021 at 08:20:45PM -0500, Tobias Neumann wrote:
> >
> > What comes to my mind when I hear Feynman integrals is work of my
> > colleague in his collaboration with DESY.
> >
> > https://risc.jku.at/m/carsten-schneider/
>
>
> The academic world is small, in fact I know a few collaborators of your
> colleague.
>
> Here is a new problem that I came across. I have a simple wrapper over sort,
> trying to sort a list of lists of integers.
>
> The interpreter has no problems with that:
>
> test := [[1,2],[2,1],[-1,1]]
>
> (4) -> sort(test)
> Function Selection for sort
> Arguments: LIST(LIST(INT))
> [1] signature: LIST(LIST(INT)) -> LIST(LIST(INT))
> implemented: slot $$ from LIST(LIST(INT))
> (4) [[- 1, 1], [1, 2], [2, 1]]
> Type:
> List(List(Integer))
>
> My wrapper implementation (code below):
>
> (5) -> mysort(test)
> Function Selection for mysort
> Arguments: LIST(LIST(INT))
> [1] signature: LIST(LIST(INT)) -> LIST(LIST(INT))
> implemented: slot (List (List (Integer)))(List (List (Integer))) from
> MYSORT
> >> System error:
> The value
> (-1 1)
> is not of type
> NUMBER
> when binding SB-KERNEL::X
>
> ---- SNIP ----
> )abbrev package MYSORT MySort
>
> MySort() : Exports == Implementation where
>
> Exports ==> with
> mysort : List(List(Integer)) -> List(List(Integer))
> Implementation ==> add
>
> if List(List(Integer)) has OrderedSet then
> mysort lst ==
> sort(lst)
> else
> error "nope"
Error looks like compiler bug. However, the correct conditon
is different, and then AFAICS code works:
if List(Integer) has OrderedSet then
mysort lst ==
sort(lst)
In this case workaround is simpler:
mysort lst == sort(_<, lst)
That is explicitely pass sorting predicate to two argument sort.
--
Waldek Hebisch
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