TyPy

A small, statically typed Python-like language written in Rust. The interpreter core uses no_std + alloc; the optional CLI runs files and a REPL.

Save as main.tp:

def twice(n: int) -> int:
    return n + n

def main() -> None:
    print(twice(21))

42

cargo run -- main.tp
cargo run -- --debug main.tp   # diagnostics go to stderr
cargo run                     # interactive REPL

• Fixed-type inference: a = 123; assigning True to a is a static error.
• Checked integers, booleans, None, arithmetic and conditionals.
• Typed functions, recursion, classes, constructors, fields and bound methods.
• Explicit imports expanded at compile time; wildcard imports are forbidden.
• Programs enter main.tp::main() -> None; libraries expose lib.tp.
• Program output uses builtin print(); bare expressions are silent in files.

Documentation covers the language, modules, CLI, internals and embedding. Current limits include no strings, containers, loops, inheritance or closures. Embedded hosts provide an allocator, platform runtime and I/O.

cargo fmt --all -- --check
cargo clippy --locked --all-targets --all-features -- -D warnings
cargo test --locked --all-features
cargo test --release --locked --all-features
cargo test --locked --no-default-features

CI checks Linux, Windows, macOS and ARM/RISC-V/Wasm cross-compilation. Complete Markdown examples are compiled and their printed output is tested.