Source code in the viua programming language

.function: bottles_of_beer_text/1
    .name: %iota number_of_bottles
    arg %number_of_bottles %0

    .name: %iota bottles_of_beer
    ; support for "1 bottle of beer" and "N bottles of beer"
    if (eq %iota %number_of_bottles (istore %iota 1)) +1 +3
    text %bottles_of_beer " bottle of beer"
    jump +2
    text %bottles_of_beer " bottles of beer"

    move %0 %bottles_of_beer
    return
.end

.function: first_print/1
    ; this function prints the
    ;
    ;   N bottles of beer on the wall
    ;   N bottles of beer
    ;   Take one down, pass it around
    ;
    .name: %iota number_of_bottles
    arg %number_of_bottles %0

    .name: %iota bottles_of_beer
    frame ^[(param %0 %number_of_bottles)]
    call %bottles_of_beer bottles_of_beer_text/1

    echo %number_of_bottles
    echo %bottles_of_beer
    print (text %iota " on the wall")
    echo %number_of_bottles
    print %bottles_of_beer
    print (text %iota "Take one down, pass it around")

    return
.end

.function: second_print/1
    ; this function prints the
    ;
    ;   No more bottles of beer on the wall /
    ;   N bottles of beer on the wall
    ;
    ; i.e. the last line of a paragraph
    .name: %iota number_of_bottles
    arg %number_of_bottles %0

    .name: %iota bottles_of_beer
    frame ^[(param %0 %number_of_bottles)]
    call %bottles_of_beer bottles_of_beer_text/1

    .name: %iota on_the_wall
    text %on_the_wall " on the wall"

    ; say "No more" instead of "0 bottles"
    if %number_of_bottles +1 +3
    echo %number_of_bottles
    jump +3
    echo (text %iota "No more")

    echo %bottles_of_beer
    print %on_the_wall

    if %number_of_bottles +1 +3
    print (text %iota "")

    return
.end

.function: bottles_of_beer/1
    .name: %iota total_number_of_bottles
    arg %total_number_of_bottles %0

    ; display first three lines of a paragraph
    frame ^[(param %0 %total_number_of_bottles)]
    call void first_print/1

    ; decrement the number of bottles
    idec %total_number_of_bottles

    ; display last line of a paragraph
    frame ^[(param %0 %total_number_of_bottles)]
    call void second_print/1

    ; immediately return if there are no more bottles
    if %total_number_of_bottles theres_more +1
    return

    .mark: theres_more
    ; if there are more bottles
    ; call the function once more
    frame ^[(pamv %0 %total_number_of_bottles)]
    tailcall bottles_of_beer/1
.end

.function: main/0
    .name: %iota total_number_of_bottles
    istore %total_number_of_bottles 9

    frame ^[(pamv %0 %total_number_of_bottles)]
    call void bottles_of_beer/1

    izero %0 local
    return
.end