Braces - compiler and virtual machine for a scheme dialect
Braces started when I worked with the wonderful book crafting interpreters, and I took that as an opportunity to:
- learn rust
- dive deeper into compilers and virtual machine implementations
I achieved both of these objectives and had a lot of fun working on this project. It implements a subset of r7rs small of the scheme programming language. I chose a scheme mostly because its evaluation semantics are very simple, as is its syntax. I came, however to discover, that the meta-syntactic ability, macros, twist your compiler-builder-brain quite a bit. The implementation is incomplete, and I will probably not finish it, but I’m content with its current state as it works for quite some scenarios and implements non-trivial language features. Among them:
- Procedural macro expander
- Automatic tail call optimization
- Efficient implementation of closures
I’m sure there are also plenty of bugs in there, but that doesn’t bother me at the moment.
Goals
- Learn how to build a bigger project using the Rust programming language
- Learn how to build a compiler and virtual machine
Non-Goals
- Build a full implementation of r7rs
Decisions
- Implement a subset of r7rs
- Implement the virtual machine as a stack machine
- Don’t implement continuations
- Implement procedural macros with explicit renaming
Examples
The following screenshot shows the braces REPL. It uses readline for completion and provides a way to tweak the level of introspection via flags. This example also shows the disassembler in action.
