RosettaCodeData/Task/Ackermann-function/Phixmonti/ackermann-function.phixmonti

def ack
    var n var m

    m 0 == if
        n 1 +
    else
        n 0 == if
            m 1 - 1 ack
        else
            m 1 - m n 1 - ack ack
        endif
    endif
enddef

3 6 ack print nl