The following program is the “Hello World” of Haskus system:
import Haskus.System main :: IO () main = runSys <| do -- Initialize the default terminal term <- defaultTerminal -- print a string on the standard output writeStrLn term "Hello World!" -- wait for a key to be pressed waitForKey term -- shutdown the computer powerOff_
It writes the “Hello World” string on the default terminal, then wait for a key to be pressed, and finally it power off the computer.
Note that unlike traditional Unix programs, we don’t use STDIN and STDOUT explicitly: we have to query a terminal and to use it explicitly.