Re: Add lilypond version predicates/operators (issue 317270043 by address@hidden)

[dak]

https://codereview.appspot.com/317270043/diff/20001/scm/lily-library.scm
File scm/lily-library.scm (right):

https://codereview.appspot.com/317270043/diff/20001/scm/lily-library.scm#newcode899
scm/lily-library.scm:899: (let* ((a (car v1)) (b (car v2))
Requires v1/v2 to have at least one element.  Admittedly quite a
reasonable precondition.

OIf we have that, we don't need (op 0 0) but can use (op a a) instead.
The advantage is that we are no longer bound to _numeric_ comparisons
then.  This lexicographic compare will then also work with string= and
similar.

https://codereview.appspot.com/317270043/diff/20001/scm/lily-library.scm#newcode903
scm/lily-library.scm:903: ((not axb) #f)
This will let (version-compare? '(2 18) < '(2 19)) deliver #f after
comparing only 2 with 2, right?

https://codereview.appspot.com/317270043/