README for Rick

Rick is a Rust INTERCAL interpreter/compiler.

Credits

Rick is modeled closely on the C-INTERCAL compiler written by Eric S. Raymond and Alex Smith, and some algorithms for built-in functionality (operators, binary I/O) is adapted from there, as well as the standard library in syslib.rs.

Also, all the sample code from the code directory comes from the C-INTERCAL distribution. See the CATALOG file there for an overview of programs.

The idea of printing fractals while compiling is taken from PyPy.

Language

A comprehensive list of INTERCAL resources, including the original manual from 1972, can be found at the C-INTERCAL page.

Rick implements the base INTERCAL-72 language with the following extensions:

• COME FROM
• Computed COME FROM
• TRY AGAIN
• Computed ABSTAIN
• Binary array I/O

The interpreter

The INTERCAL interpreter takes a source file, parses it into an AST (abstract sadist tree), and interprets the program, going through the statements until instructed to GIVE UP. This is roughly 10 times slower than a compiled version.

The compiler

Rick can also translate the AST to Rust, which is then compiled by the system Rust compiler. This is a few orders of magnitude slower than compiling the C sources generated by C-INTERCAL, but achieves about the same runtime performance (when compiled with -O), while being safe Rust code.

Rick itself uses nightly Rust features, but the generated code is stable-only.

Running

Do cargo build as usual. Then you can cargo run -- --help to see the available options for the compiler. Basic usage is cargo run -- input.i to generate an executable and cargo run -- -i input.i to interpret.

You might want to use the -b flag to get rid of an annoying compiler bug (that is mandated by the INTERCAL handbook).

Optimizations are activated with -o (optimizes INTERCAL code, recommended) and -O (makes rustc optimize machine code, not recommended unless you have lots of time or the program is very small). There are a few interesting optimizations, such as folding the entire program to a "print" statement if it does not depend on any input.

Testing

The test suite consists of input and output files for the demo programs in code. Run python test.py to run the test suite. Use the --all flag to also run the most time consuming tests, which will take about 10 minutes.

Hacking

I tried to put at least rudimentary comments into the code where it matters. If you actually want to delve deeper into the cesspool that is INTERCAL, let me know what I can do better!