[m-users.] Recursive tabled predicates with aggregates / default compare

[Julien Fischer]

Hi Mark,

On Fri, 13 Aug 2021, Mark Clements (gmail) wrote:

> I have also been looking at the RosettaCode task 
> https://rosettacode.org/wiki/Merge_and_aggregate_datasets for Mercury. I have 
> an implementation here: 
> https://github.com/mclements/rosetta/tree/main/Merge_and_aggregate_datasets. 
> Interestingly, the dates need to also allow for missing values. As a 
> question: if maybe_date is defined as
>
> `:- type maybe_date ---> date(year::int, month::int, day::int); no.`
>
> what is the default definition for 
> `compare(Compare,date(Y1,M1,D1),date(Y2,M2,D2))`?

It is described in section 3.5 of the reference manual:
<https://mercurylang.org/information/doc-latest/mercury_ref/The-standard-ordering.html#The-standard-ordering>

Julien.