bear/examples/cli_tool.vr

// cli_tool.vr — a miniature daily-driver CLI tool demonstrating the pieces a
// real command-line program needs: flag parsing, interactive input, and typed
// error handling.
//
//   import cli
//   require_name()  # (see below)
//
//   vr run examples/cli_tool.vr --name alice --verbose
//   vr run examples/cli_tool.vr --name=alice file1 file2
//
// Exit codes: 0 on success, 1 on a runtime (bad input) error, 2 on usage/flag
// errors.

import cli

fn main() {
    // --- flag parsing -------------------------------------------------------
    let name = cli.flag("name", "world")   // match --name/-n and --name=value
    let verbose = cli.has("verbose")         // match --verbose and -v
    let files = cli.positional()
    if verbose {
        println("files=" + str(files))
    }

    // --- typed throw / catchable errors -----------------------------------
    try {
        if len(name) == 0 {
            throw { kind: "usage", detail: "name must not be empty" }
        }
    } catch err {
        println("error: " + err)
        exit(2)
    }

    println("hello, " + name + "!")

    // --- interactive input -------------------------------------------------
    println("-- a quick questionnaire (pipe answers, or run interactively) --")
    let age = input("your age? ")
    if age == "" {
        println("(no answer supplied)")
    } else if int_age(age) > 0 {
        println("noted (born ~" + str(current_year() - int_age(age)) + ")")
    } else {
        println("noted")
    }

    println("done.")
}fn int_age(s) {
	try {
		return int(s)
	} catch e {
		return 0
	}
}

fn current_year() {
	// 2026 — keep in sync; or used as a stand-in for now().year
	return 2026
}