Representation independence wrt env, closures

Questions

• Homework - how did that go?
• Those of you who've gotten started on the interpreter. Eh?

Review, the interpreter

We wrote an interpreter for a small language. In a sense we can see our interpreter as defining the meaning of expressions in that language.

Interlude: A view from 10,000 feet.

Scheme -> C

Representation Independence

These are homework problems. You'll want these notes.

We want to abstract out an interface. Program to the interface. So we can change the implementation, and user code won't matter. In some sense, these say what it means to be an environment (resp., closure).

1. RI wrt environments
2. RI wrt closures

When we have made our interpreter representation-independent wrt environments, closures, we can change the implementation, and because we are programming to an interface, the usage code doesn't have to change.