# System

usleep : Int -> IO ()
unsetEnv : String -> IO Bool

  Unsets an environment variable.
  Returns true if the variable was able to be unset.

time : IO Integer

  Get the numbers of seconds since 1st January 1970, 00:00 UTC

system : String -> IO Int
setEnv : String -> String -> IO Bool

  Sets an environment variable with a given value.
  Returns true if the operation was successful.

getEnvironment : IO (List (String, String))
getEnv : String -> IO (Maybe String)

  Retrieves a value from the environment if the given key is present,
  otherwise it returns Nothing.

exit : Int -> IO ()

  Quit with a particular exit code