Macros and optimizations: it's just a phase

This post builds upon the previous one where I built the smallest OOP language I could based only on message dispatch. Everything is as late bound as possible, even the language semantics, the core only has basic data types, a call stack and logic for message dispatch.

In the previous post I implemented the semantics for evaluating expressions with enough message handlers to show arithmetic operations and binding lookups, here we are going to show that those semantics are not special, they can be just a phase in a sequence of phases that evaluate the same expression tree using different semantics.

macro phase: it quotes the right thing ™️ (if not already quoted) in reply handler definitions, name bindings and implements support for short circuit boolean operators by quoting the right hand side. When this phase is present the programmer doesn't have to quote anything.

opt phase: it applies some basic optimizations like evaluating constant sub expressions, removing unnecessary wraps and so on.

Leave a Comment