cat foo.factor f
USING: command-line.parser math ;

IN: foo

CONSTANT: COMMANDS H{
    {
        "add"
        {
            T{ option
                { name "a" }
                { type integer }
                { #args 1 }
            }
        }
    }
    {
        "subtract"
        {
            T{ option
                { name "s" }
                { type integer }
                { #args 1 }
            }
        }
    }
}

MAIN: [
    COMMANDS [ ] with-commands
]