-- :main and :run
let main = System.Environment.getArgs >>= print
:main foo bar
:main foo "bar baz"
:main ["foo", "bar baz"]
let foo = putStrLn "foo" >> System.Environment.getArgs >>= print
let bar = putStrLn "bar" >> System.Environment.getArgs >>= print
:set -main-is foo
:main foo "bar baz"
:run bar ["foo", "bar baz"]