[m-users.] add rules at runtime

[Julien Fischer]

Hi Jeff,

On Mon, 5 Nov 2018, Jeffrey Brown wrote:

> I want to write a program in Mercury that lets a user add (simple
> nonrecursive) rules at runtime, like "Bob knows Mary" or "eukaryotes
> use oxygen". Is it possible?

If you mean, is it possible to do it as in Prolog, using assert/1 and
retract/1 to modify the clause database, then no.  Mercury does not
support that.

In Mercury you would need to define your own data structures to hold the
rules added a runtime (or use some of the ones in the standard library.)

The section "Assert and retract" in the Prolog to Mercury transition
guide has further details.

Julien.