gardswag

An esoteric language, with a similar origin as XTW, designed to test the feasibility of type checking and byte code caching.

(examples are inside docs/examples)

rough language reference

License

The most important code is licensed under Apache 2.0 and CC BY-NC-SA 4.0. This causes this to be partially non-free ( because commercial usage of the most interesting parts not allowed; but should this program ever gain a compiler, the output artifacts won't be not affected by this, and can be used commercially when the license of the associated/input source code allows this ). Utilitiy crates are licensed under Apache 2.0, and if particularly simple, also under MIT.

Running the interpreter

The interpreter (and the rest of the code base) is written in Rust, and can be built using cargo, e.g.

RUST_LOG=debug cargo run --bin gardswag -- --file docs/examples/fibo.gds --mode run

Using the --mode argument it is possible to switch between

• check, which runs just the parser + type checker
• run, which then also (tries to) execute the code

It uses the tracing library for logging of debugging information, which is useful in case that tpye checking goes wrong or such. The reported information can be adjusted using the RUST_LOG environment variable.

Types

This version does not support plugins, but instead might support sockets in the future (tbd).

• bool
• int
• string
• socket (tbd)
• tagged unions (create a tagged values using .<tagname> <expr>)
• records (create using .{ <key> = <value>; <inherit_key>; })

TODO

• union partialify operator (turns an open or closed tagged union into a new open one) used to avoid "cloning matches" (match x | .a y => .a y | .b y => .b y (* ... *))
• recursive types, to make compile-time unbounded data structures possible (where we only know the size/depth at runtime)
• sockets or plugins
• lambdas with linearity spec for the argument (0, 1, *)