Why doesn't Scheme support first class environments?

Question

I\'ve been reading through SICP (Structure and Interpration of Computer Programs) and was really excited to discover this wonderful special form: \"make-environment\", which the

Answer 1

They wrote it like that because MIT Scheme does, in fact, have first-class environments, and presumably that's what the writers were planning to teach their class with (since the book was written at MIT).

Check out http://groups.csail.mit.edu/mac/projects/scheme/

However, I've noticed that MIT Scheme, while still somewhat actively developed, lacks many of the features that a really modern Scheme would have, like a foreign function interface or GUI support. You probably wouldn't want to use it for a serious software development project, at least not by itself.