[m-rev.] trivial diff: fix promise_semipure

[David Jeffery]

> IMHO this bug shows why we should allow some kind of useable syntax that
> allows you to do pattern matching without deconstruction and
> reconstruction.  If you only have to type a name once, you only have to
> get it right once.

That's such a good idea that (IIRC) Simon implemented it last year. ;-)
See 'Unification Expressions' in the reference manual.

Unification expressions are represented by '@'.

e.g. rather than

p(promise_semipure(A, B), promise_semipure(A, B)).

you can write:

p(X  @ promise_semipure(_, _), X).

...which is what you were looking for, I think.


dgj

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