CLI Reference

The Zym CLI is a single binary that compiles, runs, packages, and inspects Zym programs.

Quick Reference

File Types

• .zym — Zym source file
• .zbc — Compiled Zym bytecode (portable across platforms)
• .exe / extensionless — Standalone executable (bytecode embedded in runtime)

Script Arguments

Pass arguments to your script using -- as a delimiter. Everything after -- is forwarded to the script's main(argv) function.

zym app.zym -- --port 8080 --verbose

func main(argv) {
    print(argv);
    // → ["zym", "--port", "8080", "--verbose"]
}

Built-in Functions

print(value)

print(format, ...args)

Prints a value to standard output followed by a newline. When called with a single argument, print outputs the value directly. When called with a format string and additional arguments (up to 25), it performs formatted output with type-checked placeholders.

print("Hello, World!")            // Hello, World!
print(42)                            // 42
print([1, 2, 3])                     // [1, 2, 3]
print(true)                          // true

print("Name: %s, Age: %n", "Alice", 30)
// Name: Alice, Age: 30

print("Result: %v", [1, 2, 3])
// Result: [1, 2, 3]

print("Score: %n%% out of 100", 95)
// Score: 95% out of 100

Format Specifiers

clock()

Returns the elapsed CPU time in seconds as a number. Useful for benchmarking and measuring execution time of code sections.

var start = clock()

var sum = 0
for (var i = 0; i < 1000000; i = i + 1) {
    sum = sum + i
}

var elapsed = clock() - start
print("Took %n seconds", elapsed)

sleep(milliseconds)

Pauses execution for the given number of milliseconds. The argument must be a non-negative number.

print("Starting...")
sleep(1000)  // Wait 1 second
print("Done!")

Native Modules

The CLI extends the core language with native modules for system interaction. These are available only when running scripts through the CLI binary, not in the embedded library.