Hi there! I just ported the reference implementation of SRFI-159/166 (166 being the successor of 159) from the reference implementation in chibi scheme. The srfi document is here: https://srfi.schemers.org/srfi-166/srfi-166.html
SRFI-166 is like (ice-9 format) on steroids, drenched in molasses. It can do a lot more than (ice-9 format), but about 3x slower. I haven't started trying to make it fast just yet, but there are some low hanging fruit (like speeding up simple cases). I will wait with optimization until the srfi is finalized (and also maybe hear with Alex what he has in mind before trying to half-ass it myself). Anyway, the repo is here: https://bitbucket.org/bjoli/guile-srfi-159 . I haven't ported the tests, but playing with it in guile and chibi scheme produces the same result. Tests are up, but I'm travelling without computer the next week, so there is no time. -- Linus Björnstam
