[m-dev.] Partially instantiated data structures

Mark Brown mark at mercurylang.org
Sat Oct 6 03:51:30 AEST 2018


On Fri, Oct 5, 2018 at 11:18 PM Charlie McGee <c4cypher at gmail.com> wrote:
> I get the impression that the reason that partial instantiation got
> left by the wayside as a language feature is that, with the Mercury
> approach, by the time the compiler is done with a predicate,
> nothing should be left unbound, one way or another.

The reasons Julien just gave were:
- It would be a large undertaking.
- The Mercury developers are currently working on other things.
- In his opinion (which I share) it is unimportant in Mercury,
relative to other features.

The impression you got doesn't resemble very much what was actually said ;-)

> Remember that Mercury isn't Prolog, Mercury is Prolog's anally
> retentive younger cousin. Mercury doesn't just want your programs
> to be functionally pure and logically sound in ways that Prolog only
> pretends to be capable of, MMC will slap you wit a wet cod if they
> aren't pure and sound (unless you twist it's arm with pragmas).

I don't see that anything impure or unsound has been requested here.

(And do you really interpret compiler error messages pointing out an
inconsistency in what you've written as some sort of personal slight?
If so, I hope I never have to review any of your code!)


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