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Hello, world

Save this to hello.kt:

fun main() {
    println("Hello, klio!")
    val xs = listOf(1, 2, 3)
    println(xs.joinToString { "${it * it}" })
}

Run it:

klio run hello.kt

Hello, klio!
1, 4, 9

Running a module

When klio run gets more than one file, every file's top-level declarations are visible to every other file — single-module semantics. Exactly one fun main() must exist across the module.

klio run app/Main.kt app/Util.kt

Type-checking without running

klio check hello.kt

klio check resolves names and type-checks, emits diagnostics, and exits non-zero on any error. It does not run the program. Pass --format json or --format sarif to integrate with editors and CI; the default is plain.

What just happened?

klio run walked your source through:

  1. Lexer — UTF-8 source → token stream.
  2. Parser — tokens → AST (ast.KotlinFile).
  3. Pack loading — the embedded stdlib (and any installed packs your file imports) merge into the module.
  4. Lowering — ir lowers the AST to register IR.
  5. Vm — interp_ir builds the IR module and runs it.

klio check takes a different path after parsing: it runs the resolver and type checker to produce diagnostics. Type-checking is not part of klio run.

The klio repl command is currently a placeholder that echoes input. Use klio run for execution.