concretizer: refactor conditional rules to be less repetitious (#20507)

We have to repeat all the spec attributes in a number of places in
`concretize.lp`, and Spack has a fair number of spec attributes. If we
instead add some rules up front that establish equivalencies like this:

```
    node(Package) :- attr("node", Package).
    attr("node", Package) :- node(Package).

    version(Package, Version) :- attr("version", Package, Version).
    attr("version", Package, Version) :- version(Package, Version).
```

We can rewrite most of the repetitive conditions with `attr` and repeat
only for each arity (there are only 3 arities for spec attributes so far)
as opposed to each spec attribute. This makes the logic easier to read
and the rules easier to follow.

Co-authored-by: Massimiliano Culpo <massimiliano.culpo@gmail.com>

0 files changed, 0 insertions, 0 deletions