Re: Getting all symbols in a Scheme file as a list

[Christina O'Donnell]

Hi,

> There is no such thing as symbol definitions in Scheme – you can make 
> symbols with symbol->string, but you can’t define a symbol to 
> anything, symbols simply are.
>
> You can, however, define variables, which have a symbol as name (and 
> that name may depend on context in case of hygienic macros or renamed 
> imports/exports in modules).
Thanks for the clarification. I'll try to remember this.

> You can probably find a simpler way of doing it by locating where 
> “,binding” is implemented (in the Guile source code). It probably uses 
> the module reflection API. This API is documented in
>
> https://www.gnu.org/software/guile/manual/html_node/Module-System-Reflection.html
>
> However, the documentation is incomplete – IIRC there is a procedure 
> ‘module-bindings’ to find a list of top-level definitions, but it 
> doesn’t seem to be documented.
Got it! The REPL uses module-for-each, in (ice-9 boot-9), which is 
exported publicly:

(define (module-for-each proc module)
  "Call PROC on each symbol in MODULE, with arguments of (SYMBOL 
VARIABLE)."
  (hash-for-each proc (module-obarray module)))

This is called from (system repl command):

(define-meta-command (binding repl)
  "binding
List current bindings."
  (module-for-each (lambda (k v) (format #t "~23A ~A\n" k v))
                   (current-module)))

That'll do it for me!

> To find what modules a module uses, there is module-uses, though I 
> doubt it is reliable w.r.t. optimisation, inlining, uses of (@ (module 
> name) variable), …
>
> So, instead, I would propose to instead work  on the Tree-IL level 
> (https://www.gnu.org/software/guile/manual/html_node/Tree_002dIL.html). 
> In particular, see <toplevel-define> for definitions and 
> <module-ref>,<module-set!> for uses of other modules.
>
> This also allows for more fine-grained information – e.g. these 
> <module-ref> etc. objects contain the location in the source code, and 
> if a <module-ref> is inside a <toplevel-define> then you know that it 
> is the procedure (assuming it is a procedure) of the <toplevel-define> 
> that uses the variable of the <module-ref>.
>
> (See 
> https://www.gnu.org/software/guile/manual/html_node/The-Scheme-Compiler.html 
> for how to compile stuff – also, IIRC, the compilation procedure 
> accepts ports instead of only S-expressions, despite what the example 
> suggests.)
Thanks. I know what I'm read next.

Thank you so much for your help!
 - Christina

On 04/02/2024 21:03, M wrote:
> >I'm trying to write a Guile script to trace symbol definition and 
> reference
>
> between modules in a large Guile repo (GNU/Guix), for the purposes of 
> large
>
> scale refactoring.
>
> There is no such thing as symbol definitions in Scheme – you can make 
> symbols with symbol->string, but you can’t define a symbol to 
> anything, symbols simply are.
>
> You can, however, define variables, which have a symbol as name (and 
> that name may depend on context in case of hygienic macros or renamed 
> imports/exports in modules).
>
> >I'm wondering how I could programmatically get all the values in a
>
> Scheme file
>
> as an S-expression. From the manual, I know that the REPL has meta keyword
>
> ',binding' and ',apropos'
>
> <https://www.gnu.org/software/guile/manual/guile.html#index-apropos>
>
> which let
>
> you search and list all bindings in accessible to a module. These are
>
> exactly
>
> what I need only, since they're meta-commands, they don't produce Scheme
>
> expressions.
>
> >Does anyone have any pointers? Should I go down the route of,
>
> >    (open-input-pipe (string-append "guile -l" file "-c ,binding"))
>
> >? Seems a little bit baroque to me, I'd expect a simpler way of doing
>
> it. Any
>
> libraries anyone knows of?
>
> No. The quoting is incorrect when file has spaces, \, …, guile in PATH 
> might not be the Guile that is being run, … (For the former, consider 
> open-input-pipe*.)
>
> You can probably find a simpler way of doing it by locating where 
> “,binding” is implemented (in the Guile source code). It probably uses 
> the module reflection API. This API is documented in
>
> https://www.gnu.org/software/guile/manual/html_node/Module-System-Reflection.html
>
> However, the documentation is incomplete – IIRC there is a procedure 
> ‘module-bindings’ to find a list of top-level definitions, but it 
> doesn’t seem to be documented.
>
> To find what modules a module uses, there is module-uses, though I 
> doubt it is reliable w.r.t. optimisation, inlining, uses of (@ (module 
> name) variable), …
>
> So, instead, I would propose to instead work  on the Tree-IL level 
> (https://www.gnu.org/software/guile/manual/html_node/Tree_002dIL.html). 
> In particular, see <toplevel-define> for definitions and 
> <module-ref>,<module-set!> for uses of other modules.
>
> This also allows for more fine-grained information – e.g. these 
> <module-ref> etc. objects contain the location in the source code, and 
> if a <module-ref> is inside a <toplevel-define> then you know that it 
> is the procedure (assuming it is a procedure) of the <toplevel-define> 
> that uses the variable of the <module-ref>.
>
> (See 
> https://www.gnu.org/software/guile/manual/html_node/The-Scheme-Compiler.html 
> for how to compile stuff – also, IIRC, the compilation procedure 
> accepts ports instead of only S-expressions, despite what the example 
> suggests.)
>
> Best regards,
>
> Maxime Devos