bottles

Language: R5RS Scheme

Purpose: Print the lyrics of "99 bottles of beer on the wall".

Arguments:
N - number of bottles

Implementation:

(define (bottles . n)
  (letrec
    ((bottles
       (lambda (n suffix)
         (begin
           (display n)
           (display (if (= n 1) " bottle" " bottles"))
           (display suffix)
           (newline))))
     (verse
       (lambda (n)
         (begin
           (bottles n " of beer on the wall,")
           (bottles n " of beer.")
           (display "Take one down and pass it around,")
           (newline)
           (bottles (- n 1) " of beer on the wall."))))
     (count-bottles
       (lambda (n)
         (or (zero? n)
             (begin (verse n)
                    (newline)
                    (count-bottles (- n 1)))))))
    (cond ((null? n)
        (count-bottles 99))
      (else (count-bottles (car n))))))

Example:

(bottles 99) 
=> #t