On Sat, Feb 11, 2012 at 12:53 AM, Ludovic Courtès <l...@gnu.org> wrote: > >> * R7RS feature identifiers: r7rs, exact-closed, ratios, exact-complex, >> ieee-float, full-unicode, windows, posix, unix, darwin, linux, bsd, >> freebsd, solaris, i386, x86-64, ppc, sparc, jvm, clr, llvm, ilp32, >> lp64, ilp64, big-endian, little-endian, guile, guile-2, guile-2.0 > > I wonder how these are specified. Does a *-kfreebsd-gnu build have > ‘freebsd’? And ‘bsd’? Do *-gnu* have ‘linux’ defined, even when Linux > isn’t used? Does Cygwin have ‘unix’?
First note the list of feature identifiers is one of the things most likely to be trimmed in the next draft. There is no "gnu" feature proposed in R7RS, though Guile can of course define whatever non-portable features it needs. I don't see why "gnu" would imply "linux". The point about the "unix" feature being vague is well taken. I think it's meant to be widely encompassing and refer to Unix-like systems, including cygwin, with a guarantee of a Bourne-like shell in /bin/sh and common Unix programs like cp, rm, ls etc. available, but we'll be sure to revisit this. > And above all: are people going to write #ifdef __linux__ish code when > what they mean is #ifdef __GLIBC__ or even something different? This particular analogy doesn't apply. As I see with the current list of proposed features the only confusion is in the granularity of the feature to use, where, e.g. freebsd < bsd < posix, unix as opposed to two completely unrelated concepts like OS and libc. Regardless, we're likely to add a disclaimer that you should only resort to cond-expanded code as a last resort. -- Alex
