FAQ

Is this a real programming language, or a joke?#

Both, in that order. Baa has a hand-written lexer, a recursive-descent parser with error recovery, a real AST, a semantic analyser, a tree-walking interpreter, a standard library, a deterministic formatter, a linter, a test runner, a REPL and a project tool. It runs the ~200-line program in examples/large_program.baa and everything else in that directory. The name is the joke; the implementation is not.

Why is print called baa?#

Because it is the one word the language is named after, and because a print statement is the first thing anyone types. Everything else in the language is called what you would expect: if, else, for, while, fn, return, let, const, import, try, catch, throw, match. The sheep terminology is confined to module names, error wording and documentation.

Can I turn off the sheep jokes?#

Yes, completely.

baa --no-baa check .
BAA_NO_BAA=1 baa run app.baa

CI=true, which every CI provider sets, does it automatically. Error codes, severities and source spans are identical in both modes; only the wording changes, and a test asserts that neither wording carries information the other lacks.

Why Node and TypeScript rather than Rust?#

Rust was the obvious candidate. It lost on a practical point: building it on Windows needs the MSVC linker, and that means several gigabytes of build tools before the first compile. The full trade-offs are in ARCHITECTURE.md. The short version: no build step at all, no runtime dependencies, runs identically on three platforms, and the front end ports mechanically if the host ever changes. A Rust implementation is still an open track, and the conformance suite is there so one can prove itself against this one.

Why is there only one number type?#

Because two numeric types means silent promotions, and silent promotions mean bugs that only appear with real data. Baa's number is an IEEE-754 double: exact for integers up to 2^53, which covers every counter, index and identifier a script will meet. When you want integer behaviour you ask for it: ram.idiv, ram.floor, n.is_whole().

The cost is honest: money should not be stored in a number, in Baa or in JavaScript or in Lua. Store it in whole pennies.

Why does 1 / 0 fail instead of giving infinity?#

Because inf propagates. By the time it reaches your output it has passed through five functions and the actual mistake is far behind you. BAA306 fires where the divisor was zero, which is where you can fix it. ram.INF is there when you genuinely want infinity.

Are 0 and "" falsy?#

No. Only nil and false are. This is the Lua and Ruby rule, and it removes the classic if (count) bug where zero is a perfectly good value.

Does const make the value immutable?#

No: it freezes the binding. const flock = [] still lets you flock.push("Dolly"), because flock keeps pointing at the same array. This matches const in JavaScript and final in Java. Use clone(x) when you need a copy nobody else can reach.

Why do I have to escape { in a string?#

Because { starts an interpolation, and Baa would rather tell you about an unclosed one than guess. Write \{ for a literal brace. Inside an interpolation you write ordinary Baa, including string literals with plain quotes:

baa "the flock: {names.join(", ")}"

Why does my callback get fewer arguments than the docs say?#

It does not: it gets exactly the ones it declared. map offers (item, index) and reduce offers (total, item, index), but a callback is called with its arguments truncated to its parameter list. That is the one place Baa is lenient about arity; calls you write yourself are checked strictly, usually before the program runs.

Can I have classes?#

Not in 0.1, and possibly never. A map holding functions covers the great majority of what objects are used for in a scripting language:

fn make_counter(start) {
    let n = start
    return {
        next: fn() {
            n += 1
            return n
        },
        value: fn() { return n },
    }
}

Closures give you encapsulation; maps give you shape. Inheritance is the part that causes the trouble, and Baa is not in a hurry to add it.

How fast is it?#

About 1.2 million function calls and 4.5 million loop iterations per second on a laptop, with the front end lexing at roughly 7 MB/s. Run npm run bench for numbers from your own machine. It is a tree-walking interpreter, so it is comfortably fast for scripting and will lose to anything compiled. ARCHITECTURE.md describes the route to a bytecode VM, and why that has not been built yet.

Is there a package registry?#

No. Dependencies are local paths, declared in baa.toml under [wool] and added with baa add name --path ../name. baa add name on its own tells you the registry does not exist rather than pretending to search one. Building a registry is a security and operations problem, not a weekend feature, see ROADMAP.md.

Is shepherd.run safe?#

Safer than the usual shape of that API. It never uses a shell: it takes a program name and an explicit array of arguments, so there is no string that could be reinterpreted as shell syntax and nothing to quote-escape. A program that wants a shell has to name one, which makes the decision visible in review. See SECURITY.md.

Does Baa run on Windows?#

Yes, and it was developed there. Line endings are normalised when a file is read, so spans and diagnostics are byte-identical across platforms; paths go through Node's platform-aware path module; nothing shells out. The CI matrix covers Windows, Linux and macOS.

How do I write a test?#

In Baa, next to the code:

test "greets a sheep by name" {
    assert_eq(greet("Dolly"), "Baa, Dolly!")
}

baa test finds and runs every block. baa run registers them without running, so a test block in a program you execute costs nothing.

What does BAA stand for?#

Nothing. It is the noise.