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Quilon

Entry point

Every executable defines ^ (main); the program starts there.

^ = () -> Num => 42                              ~ no args/env
^ = (args :: []Text) -> Num => args.size         ~ command-line arguments
^ = (args :: []Text, env :: [|Text => Text|]) -> Num => env.get("HOME")   ~ args + environment

Arguments & environment. ^ may declare, in order, two typed parameters, filled at startup:

  • args :: []Text — the command-line arguments (argv), including argv[0] (the program name), so args.size is always at least 1, and args[i] is the i-th argument as a Text.
  • env :: [|Text => Text|] — the environment, as a Map from each variable’s name to its value. An entry KEY=value is split on its first = (so KEY=a=b maps KEY to a=b); an entry with no = maps the whole string to "". Read a variable with env.get("HOME") (or << core.cli’s getEnv), both giving Ok(value)/NotOk.

args is a real Quilon array (.size, [index], the array methods) and env a real Map (.get/.has/.keys/.size). A value read out of either is a full Text: the whole Text API, and overload dispatch by its concrete type.

quilon run <file> [args...] and a native build agree on args. Under run, the program sees argv = [<file>, <args...>]: the quilon/run CLI prefix is stripped and the .qn path becomes argv[0]. So quilon run f.qn a b c gives the same args.size and trailing arguments as a native ./f a b c — argv[0] is the .qn path rather than the compiled binary’s path, but everything the program indexes past it matches. (The legacy ^ = (argc :: Num, argv :: Num) form, where argv was a placeholder 0, still compiles for backward compatibility but is superseded by args :: []Text.) Any other ^ signature (e.g. a non-Text array element, or an unexpected parameter) is a compile-time error, reported by check as well as run/build.

Exit code: if ^’s body evaluates to a Num, that value is the exit code. If the body is not a Num (e.g. a side-effecting block), the program exits 0 — so an effect-only main needs no trailing 0. (This implicit-0 applies only to ^; ordinary functions always return their last expression’s value.)

(See examples/hello_world.qn and examples/args.qn.)