Error with exports that start with :

[Retropikzel]

I ran into this with the SRFI-42. It exports :, :list, :vector and such.

main.scm:

(import (scheme base)
        (foo bar))

(:hello)

foo/bar.sld:

(define-library
  (foo bar)
  (import (scheme base)
          (scheme write))
  (export :hello)
  (begin
    (define (:hello)
      (display "Hello")
      (newline))))

stklos -I . main.scm
**** Error while executing command ("main.scm")
         Where: in compiler-error
        Reason: bad exportation `#:hello'. Call was (export #:hello). Call was (import (scheme base) (foo bar))

  - error
  - compiler-error
  - %macro-expand
  - <<let/call>>
  - compile
  - #[closure 799674243840]
  - <<let/call>>
  - #[closure 7996742437c0]
  - %call-for-values
  - <<let/call>>
  - ...
Set shell variable STKLOS_FRAMES to set visible frames
EXIT

[jpellegrini]

Hello @Retropikzel !
In STklos, the starting ":" means it will be considered a keyword, not a symbol. This is configurable -- see keyword-colon-position in the manual (there's a parameter with this name, and also a directive that can be used in your scm file). But changing keyword-colon-position, even if it works, may not be interesting: you can manage to export :hello, but the other modules that import it will need to change the directive in the same way.

[Retropikzel]

@jpellegrini Hello!

Thank you for the info. I tried putting #!keyword-colon-position-none inside cond-expand but it does not seem to work there. And other implementations do not like it being outside of cond-exand.

It would be nice to have as command line argument. Or something like --r7rs which would include it and maybe in the future some other settings that are closer r7rs but would break old code.

[jpellegrini]

You can use the parameter selectively (inside cond-expand, perhaps)?

[Retropikzel]

Because #X are read by reader any other implementation will read those even inside cond-expand. With keywords themself that can be worked around by using include. But in this case it does not seem to work.

main.scm:

(import (scheme base)
        (foo bar))

(cond-expand
  (stklos #!keyword-colon-position-none)
  (else))

(:hello)

foo/bar.sld:

(define-library
  (foo bar)
  (import (scheme base)
          (scheme write))
  (cond-expand
    (stklos #!keyword-colon-position-none)
    (else))
  (export :hello)
  (begin
    (define (:hello)
      (display "Hello")
      (newline))))

Works:

stklos -I . main.scm
Hello

Does not work:

chibi-scheme -I . main.scm
ERROR on line 6 of file ./foo/bar.sld: unknown #! symbol: "!keyword-colon-position-none"
  called from <anonymous> on line 1268 of file /usr/local/share/chibi/init-7.scm
  called from <anonymous> on line 800 of file /usr/local/share/chibi/init-7.scm

Code with keywords does the same, and to get around that implementation specific code should be included. But it does not seem to work in this case.

stklos.scm:

#!keyword-colon-position-none

main.scm:

(import (scheme base)
        (foo bar))

(cond-expand
  (stklos (include "stklos.scm"))
  (else))

(:hello)

foo/bar.sld:

(define-library
  (foo bar)
  (import (scheme base)
          (scheme write))
  (cond-expand
    (stklos (include "stklos.scm"))
    (else))
  (export :hello)
  (begin
    (define (:hello)
      (display "Hello")
      (newline))))

Works:

chibi-scheme -I . main.scm 
Hello

Does not work:

stklos -I . main.scm 
**** Error while executing command ("main.scm")
         Where: in compiler-error
        Reason: bad exportation `#:hello'. Call was (export #:hello). Call was (import (scheme base) (foo bar))

  - error
  - compiler-error
  - %macro-expand
  - <<let/call>>
  - compile
  - #[closure 7d078530a840]
  - <<let/call>>
  - #[closure 7d078530a7c0]
  - %call-for-values
  - <<let/call>>
  - ...
Set shell variable STKLOS_FRAMES to set visible frames
EXIT

And even if it worked it's still quite a bit of workarounds.

[jpellegrini]

I'm unable to work on this right now, but I can imagine that the reader needs to already be told to ignore the colon before the include is found. So something like this could perhaps work?

  (cond-expand
    (stklos (begin  (keyword-colon-position 'none)
                    (include "stklos.scm")))
    (else))

[jpellegrini]

Of course, then every library or module that uses the resulting library needs to be read with the same setting, otherwise the same problem will happen (:hello will be read as a keyword).

I agree that the best solution would be a command-line flag.

[Retropikzel]

I'm unable to work on this right now

It is not urgent. I have only run into it with this SRFI, and I'm just testing and packaging them and not yet using them.

[egallesio]

Hi, I have not completely seen the details of this issue, but I already saw that #!keyword-colon-postion-xxx doesn't work as intended. I need to investigate more on this point.

Anyway, a possible solution before a real fix consists of placing a (keyword-colon-position 'none) in your ~/.config/stklos/stklosrc file.

[egallesio]

BTW, using bars around symbols which start with a colon is another solution, and it works everywhere AFAIK.

stklos>  (define (|:foo|) 'hello)
;; :foo
stklos> (|:foo|)
hello

Of course, it will change your source file, and perhaps it is not convenient for you (and undeniably ugly).

[egallesio]

Hi,

This is fixed in the last commits. One way could be to use the directives #!keyword-colon-position-xxx directly in your file. But it is not portable, since the syntax #!something will break on some Scheme implementations (in STklos it is a one line comment, which can be used for directives, but also as a stance for running a Scheme script as a command if placed on the first line).

A portable way is to use (when-compile (keyword-colon-position 'none). This can be used in a cond-expand. For instance, you can add the following lines at the start of foo/bar.sld:

(cond-expand
 (stklos (when-compile (keyword-colon-position 'none)))
 (else #f))

If you want to compile file foo/bar.sld, use when-load-and-compile. The compiler will be instructed to consider :hello as a symbol, and, when the file will be loaded later, this will be the case too.

[jpellegrini]

I think #901 is relevant...