99 Bottles of Beer/Lisp

99 Bottles of Beer done in Lisp-languages

99 Bottles of Beer/Lisp is part of 99 Bottles of Beer. You may find other members of 99 Bottles of Beer at Category:99 Bottles of Beer.

Common Lisp

Sensible solution

<lang lisp>(defun bottles (x)

 (loop for bottles from x downto 1
       do (format t "~a bottle~:p of beer on the wall

~:*~a bottle~:p of beer Take one down, pass it around ~a bottle~:p of beer on the wall~2%" bottles (1- bottles))))</lang> and then just call <lang lisp>(bottles 99)</lang>

Ridiculous

<lang lisp>(format t "~{~[~^~]~:*~D bottle~:P of beer on the wall~%~:*~D bottle~:P of beer~%Take one down, pass it around~%~D bottle~:P~:* of beer on the wall~2%~}"

         (loop :for n :from 99 :downto 0 :collect n))</lang>

The FORMAT function is probably the most baroque (i.e. featureful almost to a fault) function in Common Lisp. To really drive this point home, try replacing each instance of ~D with ~R, and then with ~@R. Yes, this is all standard and dependable (dys?)functionality.

Explanation of the format string for the uninitiated:

• ~{fmt~} expects the next argument to be a list (which is of the integers from 99 down to 0), and executes the format string fmt on each element. It is essentially a map or foreach.
• ~[...~] is a case/switch. It executes the nth clause, where n is taken from the next argument. Since there is only one clause here, it will be executed only when the argument is 0.
• ~^ will terminate formatting.
• ~:* will back-up to the most-recently used argument.
• ~D prints the next argument as a decimal number.
• ~:P is for English plurals: it prints s if the last argument wasn't 1; it prints nothing otherwise. There's also ~@P for y/ies, in case you were worried about that.

Note, by the way, how the emoticons :*~D and :P have shown up in the format string. FORMAT is so powerful, it's even self-aware about how silly it is.

PicoLisp

<lang PicoLisp>(de bottles (N)

  (case N
     (0 "No more beer")
     (1 "One bottle of beer")
     (T (cons N " bottles of beer")) ) )

(for (N 99 (gt0 N))

  (prinl (bottles N) " on the wall,")
  (prinl (bottles N) ".")
  (prinl "Take one down, pass it around,")
  (prinl (bottles (dec 'N)) " on the wall.")
  (prinl) )</lang>