std.io

Console I/O: printing without newlines and reading from stdin.

import std.io

Functions

print / println

io.print(s: string)      // write to stdout, no trailing newline
io.println(s: string)    // write to stdout with trailing newline

Note: The built-in print() (no import needed) already prints with a newline. io.print() is useful when you need to write a prompt on the same line as user input.

read_line

io.read_line() string

Reads one line from stdin (blocking). Returns the input without the trailing newline.

Example: Interactive Prompt

import std.io

fn main() int? {
    io.print("What is your name? ")
    let name = io.read_line()
    print(f"Hello, {name}!")

    io.print("Enter a number: ")
    let n = io.read_line().to_int()?
    print(f"Doubled: {n * 2}")

    return none
}

to_int() returns int? – it yields none if the string is not a valid integer. The ? operator propagates the none value, causing the function to return early.