Comment by technomancy

Fennel is continually tested against mainline Lua 5.1, 5.2, and 5.3 as well as LuaJIT: https://github.com/bakpakin/Fennel/blob/master/Makefile#L6

It works great with Fengari for client-side scripting; in fact this is what we use on the web site for the live REPL. We have run some tests against other obscure implementations such as Luerl and Rembulan but have encountered some bugs in those compilers that need to get addressed before they get integrated into the test suit.