There was a bit of SRFI-98 discussion in July 2008 about adding setenv and unsetenv, but it never went anywhere. I think I didn't pursue it then because they are Posix but not ISO C. So yes, SRFI-170 seems like a good place.
Can you prepare a PR against Harold's repo, at least for the document? Thanks.
R7RS has `get-environment-variable` and `get-environment-variables`
(presumably via SRFI 98).
Is `set-environment-variable` standardized anywhere? If not, would SRFI
170 be a good place for it?