This relies on “scope stacks”, which are another piece that I didn’t really have a chance to discuss in either the blog post or Strange Loop talk. In brief, the

This relies on “scope stacks”, which are another piece that I didn’t really have a chance to discuss in either the blog post or Strange Loop talk. In brief, they allow you to “package up” context from one part of a file and “send it over” to another part of a (possibly different) file. We use that to model the (types of the) actual parameters passed into a function call or generic type instantiation, for instance. Scope stacks are essential for both of the more advanced examples I mention at the end of the post.