Re: case source code

[Damien Mattei <damien.mattei@gmail.com>]

thanks, if just replaced the 'begin by 'let () to allow internal
definitions but i haven't test it yet (finally no need in my code of define
internal at this point)
regards,
Damien

On Mon, Sep 12, 2022 at 10:47 AM Taylan Kammer <taylan.kammer@gmail.com>
wrote:

> On 12.09.2022 09:42, Damien Mattei wrote:
> >
> > Hello,
> > i can not find in the scheme community a definition of 'case in term of
> macro as for when, unless,while,do... does anyone have it?
> > thanks,
> > Damien
>
> The RnRS often contain such definitions.  The following is taken from
> R7RS-small:
>
> (define-syntax case
>   (syntax-rules (else =>)
>     ((case (key ...) clauses ...)
>      (let ((atom-key (key ...)))
>        (case atom-key clauses ...)))
>     ((case key (else => result))
>      (result key))
>     ((case key
>        (else result1 result2 ...))
>      (begin result1 result2 ...))
>     ((case key
>        ((atoms ...) result1 result2 ...))
>      (if (memv key ’(atoms ...))
>          (begin result1 result2 ...)))
>     ((case key
>        ((atoms ...) => result))
>      (if (memv key ’(atoms ...))
>          (result key)))
>     ((case key
>        ((atoms ...) => result)
>        clause clauses ...)
>      (if (memv key ’(atoms ...))
>          (result key)
>          (case key clause clauses ...)))
>     ((case key
>        ((atoms ...) result1 result2 ...)
>        clause clauses ...)
>      (if (memv key ’(atoms ...))
>          (begin result1 result2 ...)
>          (case key clause clauses ...))))
>
> --
> Taylan
>
>