Re: SRFI 193 (Command lines) for Chicken

[Kon Lovett]

i will take a stab at some of these

> On Aug 8, 2020, at 5:14 AM, Lassi Kortela <lassi@lassi.io> wrote:
> 
> Hello,
> 
> SRFI 193 is in the last-call period before finalization. Here is an
> implementation for Chicken. I'd like to publish it as an egg. The API
> is trivial enough that if you like it, you may want it in core.
> 
> The code works as is, but has the following issues:
> 
> - It's Chicken 5 only. Could it be easily backported to 4?

yes

> 
> - It checks for the magic string "csi" to figure out whether running
>  in csi or in a standalone program compiled using csc. The check is
>  dodgy; what would be a proper way to do it?

csi adds feature identifiers at runtime: 
(http://wiki.call-cc.org/man/5/Module%20(chicken%20platform)#features)

                csi                             always
                chicken-script          when -ss, -sx, -s, -script

otherwise not the interpreter

(cond-expand
  (chicken-script       (main (command-line-arguments)) )
  (csi                  (display “run it yourself”) (newline) )
  (else                 (main (command-line-arguments)) ) )


> 
> - Pathname handling is not cross-platform. It uses `string-append`
>  with "/" to build pathnames, and feeds the result to
>  `normalize-pathname` to resolve relative pathnames into absolute.
>  How does one get the host platform's directory separator, and would
>  there be cleaner ways to write the pathname parts in general?

(make-pathname "foo" “")        =>      "foo/“

(make-pathname "foo” “bar")     =>      “foo/bar“

- while (chicken pathname) knows the separator, it does not export ;-)

> 
> Thanks to anyone who can spare a moment to help a noob :)
> 
> ;;; ----------------------------------------------------------------------
> 
> (module srfi-193
>    (command-line command-name command-args script-file script-directory)
> 
>  (cond-expand
>    (chicken-5
>     (import scheme (chicken base) (chicken module) (chicken pathname)
>             (rename (only (chicken process-context)
>                           current-directory
>                           argv command-line-arguments program-name)
>                     (argv                   chicken/argv)
>                     (command-line-arguments chicken/command-line-arguments)
>                     (program-name           chicken/program-name)))))
> 
>  ;;; Fundamental
> 
>  ;; csi -script  => "filename.scm"
>  ;; csi repl     => #t
>  ;; exe from csc => #f
>  (define interpreted
>    (let ((arg0 (car (chicken/argv))))
>      (and (equal? "csi" (pathname-file arg0))
>           (if (equal? "csi" (chicken/program-name)) #t
>               (chicken/program-name)))))
> 
>  (define (script-file)
>    (and (string? interpreted)
>         (normalize-pathname
>          (string-append (current-directory) "/" interpreted))))
> 
>  (define command-line
>    (make-parameter (if (eqv? #t interpreted) '("")
>                        (cons (or (script-file) (chicken/program-name))
>                              (chicken/command-line-arguments)))))
> 
>  ;;; Derived
> 
>  (define (command-name)
>    (let ((file (car (command-line))))
>      (and (not (equal? "" file))
>           (pathname-file file))))
> 
>  (define (command-args)
>    (cdr (command-line)))
> 
>  (define (script-directory)
>    (let ((file (script-file)))
>      (and file (string-append (pathname-directory file) "/")))))
>