Re: unhandled constant?

["Linus Björnstam" <linus.bjornstam@veryfast.biz>]

Did you try just expanding it to a define? Or just output a module-define! at runtime and run a module-define! at compile time.



-- 
  Linus Björnstam

On Sat, 1 Feb 2020, at 10:54, Han-Wen Nienhuys wrote:
> Here is an example that shows better how things work, and what might
> be the cause of my problems. Is it right that programmatically set
> contents of "current-module" are not serialized into the compiled
> file?
> 
>    (define (run-at-compile-time cmd)
>      (module-define! (current-module) (string->symbol cmd) #t)
>      (format (current-error-port) "I-am-called-at-compile-time ~a\n" cmd))
> 
>   (define (runtime-call cmd)
>     (format (current-error-port) "I-am-called-at-runtime ~a\n" cmd)
>     (format (current-error-port) "val ~a\n"
>             (module-ref (current-module) (string->symbol cmd))))
> 
>   (defmacro foo (cmd . rest)
>   (run-at-compile-time cmd)
>   `(runtime-call ,cmd))
> 
>   (foo "xy")
> 
> $ guile1.8 ew.scm
> I-am-called-at-compile-time xy
> I-am-called-at-runtime xy
> val #t
> 
> this is compatible with 2.2 without compilation,
> 
> $ GUILE_AUTO_COMPILE=0 guile2.2 ew.scm
> I-am-called-at-compile-time xy
> I-am-called-at-runtime xy
> val #t
> 
> but compilation fails
> 
> $ GUILE_AUTO_COMPILE=1 guile2.2 ew.scm
> ;;; note: auto-compilation is enabled, set GUILE_AUTO_COMPILE=0
> ;;;       or pass the --no-auto-compile argument to disable.
> ;;; compiling /home/hanwen/vc/lilypond/ew.scm
> ;;; WARNING: compilation of /home/hanwen/vc/lilypond/ew.scm failed:
> ;;; Unbound variable: run-at-compile-time
> 
> $ guild2.2 compile ew.scm
> Backtrace:
> In system/base/target.scm:
>      57:6 19 (with-target _ _)
> In system/base/compile.scm:
> ..
> Unbound variable: run-at-compile-time
> 
> 
> If I encapsulate the run-at-compile-time definition with
> 
>  (eval-when
>   (compile eval)
> 
> it works if I remove the module manipulation, but the module-ref
> doesn't work. It looks like the settings from module-define! are not
> serialized into the byte code, so I can't have code that relies on
> correspondence between module-define driven from macros and module-ref
> during evaluation.
> 
> [hanwen@localhost lilypond]$ guild2.2 compile ew.scm
> I-am-called-at-compile-time xy
> wrote 
> `/home/hanwen/.cache/guile/ccache/2.2-LE-8-3.A/home/hanwen/vc/lilypond/ew.scm.go'
> [hanwen@localhost lilypond]$ GUILE_AUTO_COMPILE=0 guile2.2 ew.scm
> I-am-called-at-runtime xy
> Backtrace:
>            6 (apply-smob/1 #<catch-closure 56514b4c37a0>)
> In ice-9/boot-9.scm:
>     705:2  5 (call-with-prompt ("prompt") #<procedure 56514b4d5c60 …> …)
> In ice-9/eval.scm:
>     619:8  4 (_ #(#(#<directory (guile-user) 56514b591140>)))
> In ice-9/boot-9.scm:
>    2312:4  3 (save-module-excursion #<procedure 56514b54b330 at ice-…>)
>   3832:12  2 (_)
> In ew.scm:
>     10:10  1 (runtime-call "xy")
> In unknown file:
>            0 (scm-error misc-error #f "~A ~S ~S ~S" ("No variabl…" …) …)
> 
> ERROR: In procedure scm-error:
> No variable named xy in #<directory (guile-user) 56514b591140>
> 
> On Fri, Jan 31, 2020 at 9:01 PM Linus Björnstam
> <linus.bjornstam@veryfast.biz> wrote:
> >
> > Read the docs. That seems to be a documentation bug. Try fiddling with the arguments to eval when and see if you can make it work.
> >
> > --
> >   Linus Björnstam
> >
> > On Fri, 31 Jan 2020, at 20:17, Han-Wen Nienhuys wrote:
> > > On Fri, Jan 31, 2020 at 7:20 PM Linus Björnstam
> > > <linus.bjornstam@veryfast.biz> wrote:
> > > > I don't really understand your question. With defmacro and syntax-case you can run arbitrary code. If you just output code that does module-define! that won't be run until runtime, and thus you cannot depend on the result of that module-define! during expansion. You can however wrap it in an eval-when to solve that issue. That allows you to specify when code gets run. With module-define! I personally find it all a bit icky, but I usually stay as far away from phasing as I can :)
> > >
> > >  eval-when looks like it might be a solution to the puzzle , but
> > > honestly, the doc at
> > >
> > > https://www.gnu.org/software/guile/manual/html_node/Eval-When.html
> > >
> > > has me mystified.  When I run the example through guile 2.2 and
> > > display *compilation-date*,
> > >
> > > I get a different answer each time. Shouldn't it be a fixed timestamp
> > > (of when the compile happened?)
> > >
> > > [hanwen@localhost lilypond]$ guile2.2 e.scm
> > > ;;; note: source file /home/hanwen/vc/lilypond/e.scm
> > > ;;;       newer than compiled
> > > /home/hanwen/.cache/guile/ccache/2.2-LE-8-3.A/home/hanwen/vc/lilypond/e.scm.go
> > > ;;; note: auto-compilation is enabled, set GUILE_AUTO_COMPILE=0
> > > ;;;       or pass the --no-auto-compile argument to disable.
> > > ;;; compiling /home/hanwen/vc/lilypond/e.scm
> > > ;;; compiled
> > > /home/hanwen/.cache/guile/ccache/2.2-LE-8-3.A/home/hanwen/vc/lilypond/e.scm.go
> > > Fri Jan 31 20:15:57+0100 2020
> > > [hanwen@localhost lilypond]$ guile2.2 e.scm
> > > Fri Jan 31 20:15:58+0100 2020
> > > [hanwen@localhost lilypond]$ guile2.2 e.scm
> > > Fri Jan 31 20:16:00+0100 2020
> > >
> > > --
> > > Han-Wen Nienhuys - hanwenn@gmail.com - http://www.xs4all.nl/~hanwen
> > >
> 
> 
> 
> -- 
> Han-Wen Nienhuys - hanwenn@gmail.com - http://www.xs4all.nl/~hanwen
>