Re: Use define-syntax for define-session[-public] (issue 553480044 by address@hidden)

[hanwenn]

https://codereview.appspot.com/553480044/diff/557280043/scm/lily.scm
File scm/lily.scm (right):

https://codereview.appspot.com/553480044/diff/557280043/scm/lily.scm#newcode111
scm/lily.scm:111: "This defines a variable @var{name} with the starting
value
On 2020/02/01 21:37:50, dak wrote:
> An interesting DOC string method...  define-syntax doesn't have
anything like
> that?


no, doesn't look like it.

I added all the GUILE repos I could find to cs.bazel.build, none of the
define-syntax uses seem to have doc strings. See

https://cs.bazel.build/search?q=define-syntax%20f%3ascm%20&num=450

https://codereview.appspot.com/553480044/diff/557280043/scm/lily.scm#newcode123
scm/lily.scm:123: (define-syntax define-session
On 2020/02/01 21:37:50, dak wrote:
> The problem with define-syntax is that in Guile-1.8, it doesn't work
properly
> because of some symbol changing behavior when defined, a bug that will
not get
> fixed any more.  I wish I'd remember what it was.  It was something
short like
> \once or \temporary or so.  One could use it in the LilyPond core, but
it failed
> in user documents.  Ah right: pretty sure it was \void (namely the
symbol 'void
> being bound to something).
> 
> That makes it hard for people to get acquainted with it and maintain
it in
> consequence.  So let's see whether we manage to muddle through in a
different
> manner.  Do you have a useful test case?  Should I just draw out the
> define-session thing and try to convince Guile-2.0 with the right
incantations
> to byte compile it?  I assume this is the same in Guile-2.2 (for which
I have an
> Ubuntu package I don't need to compile)?
> 
> Would this give us a chance to get somewhere?

Please see Taylan's reply to the guile-devel list, which gives a
succinct explanation of why inner functions in macros can never work in
the Guile 2.x compiler. So we either forego compilation (at a 1.5 sec
startup cost) or we rewrite the macros to stop using inner functions.

What is the problem precisely with void ? I assume that is not about
define-session but for define-music-function, which looks like it has a
very complex macro expansion.

Can you provide a repro scenario?

Another option: we decide that as of LilyPond 2.21, you will need GUILE
2.2 for LilyPond, and then we can rewrite the Scheme code without having
to worry about G1.8 bugs.  With the performance tuning on BDWGC, I think
this a viable strategy too.

https://codereview.appspot.com/553480044/