[r6rs-discuss] Re: [Formal] formal comment (ports, characters, strings, Unicode)

From: William D Clinger <will>
Date: Tue Mar 20 09:53:53 2007

I am posting this as an individual member of the Scheme
community. I am not speaking for the R6RS editors, and
this message should not be confused with the editors'
eventual formal response.

Shiro Kawai wrote:

> I'm curious. You were talking "string-ref and string-set!"
> until previous paragraph, but here you dropped string-set!.
> Is it intentional or just an overlook?

It was intentional, but not very significant. With several
plausible representations, multi-threaded systems would
need synchronization. I think it's pretty easy to arrange
for string-ref to be delayed only if a string-set! is in
progress, but string-set! requires mutual exclusion, which
might be implemented using some protocol that doesn't
guarantee O(1) time but works well enough in practice.

> If it is intentional, is it beacause you think that O(1)
> string-set! is less important?

string-set! is definitely less important than string-ref,
but it's still important.

Will
Received on Tue Mar 20 2007 - 09:53:47 UTC