It's been done as other comments pointed out. But the fact that you can do it is mildly interesting, isn't it? It's a sort of bootstrapping problem. Obviousl

It's been done as other comments pointed out. But the fact that you can do it is mildly interesting, isn't it? It's a sort of bootstrapping problem. Obviously you can't trigger full GC in your GC code. So you have to write GC code in such a way that it won't trigger GC or, in some cases, very limited mode of GC that you know is safe to perform at that point. It is trickier in languages that implicitly allocates. Traditionally, Lisp programmers are pretty aware of what operation would allocate and good at avoiding them. Plus, an implementation often provide a primitive to turn off GC in certain regions. Another approach is to design a subset of language with guaranteed safety properties and implement the core part of GC with it.