io

The io module provides console input/output functions. Requires import io. All functions are effect fn.

Function Reference

Function	Signature	Description
read_line	() -> String	Read a single line from stdin
print	(String) -> Unit	Print to stdout without trailing newline
read_all	() -> String	Read all of stdin as a single string

Examples

import io

effect fn prompt(msg: String) -> Result[String, String] = {
  io.print(msg)
  let answer = io.read_line()
  ok(answer)
}

effect fn main(args: List[String]) -> Result[Unit, String] = {
  io.print("Enter your name: ")
  let name = io.read_line()
  println("Hello, " + name + "!")
  ok(())
}

Note: println is a built-in function (no import needed) and always appends a newline. Use io.print when you need output without a trailing newline, such as prompts.