There isn't an active maintainer any more, I'm afraid. And Apple placed restrictions on modifying memory that contains instructions that prevented techniques t

There isn't an active maintainer any more, I'm afraid. And Apple placed restrictions on modifying memory that contains instructions that prevented techniques the compiler relies upon for fast allocation of closures. There are ideas for workarounds, but they would require a lot of work. I'm a huge fan of MIT Scheme, and have used it since 1984, but I would recommend using another implementation these days, especially on Mac. See Scheme.org.