Indeed, and as far as I know Scheme JVM implementations, which I haven't looked at in a long while, either do it per the spec and are slow, SISC reputedly, died

Indeed, and as far as I know Scheme JVM implementations, which I haven't looked at in a long while, either do it per the spec and are slow, SISC reputedly, died about the time I might have started using it, or go through contortions like Kawa to do the best you can. Don't know about JScheme, it was dead before then, and I just noticed Bigloo will compile to the JVM, adding one to the list of 4.