Robby Findler writes:

> >   This SRFI cannot be supported by all Schemes. Therefore, by using it
> >   you are restricting the portability of your code.
>
> Isn't this true, in principle, of all the SRFIs?

No and yes.

It is certainly true that not all SRFIs *are* implemented in all
Schemes. However, most SRFIs *can* be implemented in all R5RS-compatible
Schemes, often trivially. This SRFI (and possibly certain others)
*cannot*.

The following two examples illustrate the difference:

  If I write code that uses SRFI-1 and then discover that I want or need
  to run the code in a Scheme that doesn't implement SRFI-1, I can
  simply load Olin's reference implementation.

  If I write code that uses SRFI-55 and then discover that I want or
  need to run the code in Scheme48, I am hosed.

Regards,

Alan
--
Dr Alan Watson
Centro de Radioastronomía y Astrofísica UNAM