Just finished a first cut Chibi Scheme implementation of 3.1  Errors, except I noticed this line in the section:

For reference purposes, the POSIX errno numbers are bound to the variables errno/perm, errno/noent, etc. See the POSIX specification of errno.h for the complete list.

And I wonder for what purposes this is required.  Faking an error when calling errno-error to raise an exception works, otherwise, I've generally desired the reverse mapping.  Which the UNIX/POSIX world has not seen fit to provide besides requiring you to follow a trail of crumbs to find the real file, on my Bionic Beaver it totals 5 files after /usr/include/errno.h.  And of course the message string for humans doesn't include preprocessor define strings like "ESRCH", just "No such process".  Oh, even better, I just noticed the latest POSIX standard says ESTALE is "Reserved", but my Linux defines it as "Stale file handle".

Creating errno/perm etc. will be a bit obnoxious if there are systems out there that don't actually define all of the POSIX set (and of course they can define additional ones, which this SRFI can't require including).  But not that big a deal if there's value to it.

- Harold