The parser and some lowering passes are still written in femtolisp. There has been some discussion of switching to the native JuliaParser package [1]. However, JuliaParser doesn&#x27;t implement the fairly tricky lowering passes that the femtolisp parser does. I personally would prefer to have the parser in Julia, but at this point the most pressing issue with parsing and lowering is speed – so it&#x27;s possible that the parsing and lowering will be converted to C instead.<p>[1] <a href="https:&#x2F;&#x2F;github.com&#x2F;JuliaLang&#x2F;JuliaParser.jl" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;JuliaLang&#x2F;JuliaParser.jl</a>