Quick start

The fastest way to try Tantu is the playground, which runs the real interpreter in your browser, with no install. Every code block in these docs has a **Try it ** button (hover to reveal it) that opens the snippet there.

Hello, world

fn main() -> Unit:
    print("hello, world")

Try it

Every program starts at fn main(). The -> Unit return type means "returns nothing"; you can omit it and Tantu infers Unit. Blocks are defined by indentation (spaces only; tabs are an error), just like Python.

A first real program

fn greet(name: Str) -> Str:
    return "Hello, " + name + "!"

fn main() -> Unit:
    print(greet("Tantu"))
    let nums = [1, 2, 3, 4, 5]
    var total = 0
    for n in nums:
        total = total + n * n
    print(total)

Try it

A few things to notice:

• let binds an immutable value; var binds a mutable one. Reach for let by default.
• Function parameter and return types are required; that is the boundary where you tell the checker what you mean; the bodies are inferred from there.
• + concatenates strings and adds numbers; lists are joined with concat (see Builtins).

Running Tantu locally

The playground is the real interpreter, but you can also run Tantu from the command line:

python -m tantu run file.tn     # run a program (use `run -` to read stdin)
python -m tantu check file.tn   # type-check only, no run
python -m tantu dis file.tn     # disassemble to bytecode
python -m tantu                   # REPL

Exit codes are meaningful: 0 success, 1 a runtime panic, 2 a compile-time (lex, parse, or type) error.

Where to next

• The Language tour walks through the whole language with runnable examples.
• Types & no-null explains how Tantu models absence and failure.
• Concurrency covers fibers, channels, and select.