Re: On keywords, symbols, and reader options

[Marius Vollmer]

Matthias Koeppe <address@hidden> writes:

> I find Guile's treatment of keywords confusing and counter-productive.
> In this article, I first discuss a few issues; then I propose a
> change.

Very short answer: for portability, I think you should avoid using
keywords altogether.  Do not use (read-set! keywords 'prefix) for your
code when it runs in Guile.

>  1. Remove the notion of keywords; just make them symbols with a
>     leading colon.
>
>  2. Introduce a module variable KEYWORD-STYLE, which can be one of #f
>     and 'prefix.  If set to prefix, all symbols starting with a colon
>     are self-evaluating. 

Hmm, this amounts to making keywords a subtype of symbols, right?

    (define (keyword? obj)
      (and (symbol? obj)
           (> (string-length (symbol->string obj)) 0)
           (char=? (string-ref (symbol->string obj) 0) #\:)))

Also, it would move the determination of whether something behaves
like a keyword from read time to execution time.

I like the current setup better, where keywords are constructed at
read-time and treated the same at execution time.

>  3. Add a DEFINE-MODULE keyword argument :KEYWORD-STYLE which sets the
>     module variable.

What we probably should do is to make load-module save/restore the
reader options around loading the file.