SRFI 179: Nonempty Intervals and Generalized Arrays (Updated), an
extension of SRFI 122, has been added as a module to LambdaNative, which
the developers describe as

LambdaNative is an open-source (BSD licensed) cross-platform development
environment written in Scheme (Gambit-C), supporting Android, iOS,
BlackBerry 10, OS X, Linux, Windows, OpenBSD, NetBSD, FreeBSD and OpenWrt.

https://www.lambdanative.org/
https://github.com/part-cw/lambdanative

LambdaNative is written in Gambit Scheme, which has portability as one
of its primary goals.

https://github.com/gambit/gambit
http://gambitscheme.org/wiki/index.php/Main_Page
https://gitter.im/gambit/gambit

Brad