Syntax: numbers prefixed with # or not

[Valentin Villenave]

Greetings,

Alongside issue #5473, I’ve started investigating whether numbers
still require to be prefixed with #.
AFAICS, the only ones that still do are in markups and all markups
commands, but hardly anywhere else; which _could_ make LilyPond syntax
a tiny bit easier to grasp for new users…
Or we can still use # everywhere as a matter of principle, even though
it’s no longer a hard requirement. (Pro: less possible confusion with
durations and better consistency with markup commands; Con: it’s one
of those things experienced LilyPonders hardly notice anymore, but
that do make the entry code a tad more exotic-looking to newcomers.)

My proposal would be to add convert-ly rules for:
-any \override, \set or \tweak involving a number-defined property
(including integers, decimals and negative numbers).

-also handle properties defined at the context-creation level, i.e. in
\with or \layout blocks.

-any music functions with a number arg:
barNumberCheck
finger
harmonicByFret
harmonicByRatio
mark
ottava
rightHandFinger
shiftDurations
as well as phrasingSlurDashPattern, slurDashPattern and tieDashPattern
(and the new \dropNote etc. functions I recently added).
Now,this may be tricky as some of those have optional args,
number-or-markup args etc. Things like \ottava are quite
straightforward, though.

-Mainly use non-# numbers in the docs, that is: everywhere *except* in
NR1.8 Markup where we’d need to explain that markup commands require
numbers to be explicitely handled as Scheme tokens.

-To stay on the safe side, possibly leave user-defined music functions
unchanged for now. (Which includes some regtests like
input/regression/rest-ledger.ly and quite a bunch of LSR snippet.)

… Or, we just don’t bother and keep using (and recommending) # everywhere.
Thoughts?

Cheers,
V.