The programming language of crash test dummies.

A lot of posts here are about how to show a language to be well-behaved for some definition of well-behaved.

How about the opposite? How do we construct a language which, while it has a well-behaved and consistent subset, also allows us to reproduce and demonstrate every kind of important semantic problem and ambiguity that a student needs to be aware of and understand? Or serve as a "direct" translation target for programs written in languages that had those problems?

By "direct" I mean we may need to define operations and locally transform syntax to the new language, but we wouldn't need to write an interpreter to achieve, eg, their problematic calling discipline or argument passing or exception handling or the way their dynamic environments interfered with their macrology.

Ideally, the constructions that are connected to known problems would form a "minimal set" -- ie, we would like to introduce the smallest number of such constructs possible to get a complete map of these problems, and be able to demonstrate each concept.

So what would you look for in a language intended to demonstrate *unsafe* behavior, especially in correct implementations of features that some reasonably smart people once thought were good ideas?