l33tsp34k in scheme

; l33tsp34k:
; (display (l33t "You know, I truly wanna kill whomever came up with entries for M, N, Y and W."))
(define (l33t s)
  (apply string-append
         (map (lambda (c)
                (let ((trns (assoc c l33t-table)))
                  (if trns
                      (vector-ref (cdr trns) (random! (vector-length (cdr trns))))
                      (string c))))
              (upper (string->list s)))))

(define l33t-table
  (map (lambda (x) (cons (car x) (apply vector (cdr x))))
       '((#\A "4" "@" "/-\\" "/\\" "^" "aye" "∂" "ci" "λ" "Z")
         (#\B "8" "|3" "6" "13" "|3" "ß" "]3")
         (#\C "(" "<" "¢" "{" "©" "sea" "see")
         (#\D "|)" "[)" "∂" "])" "I>" "|>" "0" "ð" "cl")
         (#\E "3" "£" "&" "€" "[-" "ə")
         (#\F "|=" "]=" "}" "ph" "(=" "ʃ")
         (#\G "6" "9" "&" "(_+" "C-" "gee" "jee" "(γ," "cj")
         (#\H "|-|" "#" "]-[" "[-]" ")-(" "(-)" ":-:" "}{" "}-{" "aych")
         (#\I "!" "1" "|" "eye" "3y3" "ai" "¡")
         (#\J "_|" "_/" "]" "¿" "</" "_)" "ʝ")
         (#\K "X" "|<" "|X" "|{" "ɮ")
         (#\L "1" "7" "|_" "£" "|" "|_" "lJ" "¬")
         (#\M "44" "/\\/\\" "|\\/|" "em" "|v|" "IYI" "IVI" "[V]" "^^" "nn"
              "//\\\\//\\\\" "(V)" "(\\/)" "/|\\" "/|/|" ".\\\\" "/^^\\" "/V\\" "|^^|" "AA")
         (#\N "|\\|" "/\\/" "//\\\\//" "И" "[\\]" "<\\>" "{\\}" "//" "₪" "[]\\[]" "]\\[" "~")
         (#\O "0" "()" "oh" "[]" "¤" "Ω")
         (#\P "|*" "|o" "|º" "|>" "|\"" "?" "9" "[]D" "|7" "q" "þ" "¶" "℗" "|D")
         (#\Q "0_" "0," "(,)" "<|" "cue" "9" "¶")
         (#\R "|2" "2" "/2" "I2" "|^" "|~" "lz" "®" "|2" "[z" "|`" "l2" "Я" ".-" "ʁ")
         (#\S "5" "$" "z" "§" "es")
         (#\T "7" "+" "-|-" "1" "']['" "†")
         (#\U "|_|" "(_)" "Y3W" "M" "µ" "[_]" "\\_/" "\\_\\" "/_/")
         (#\V "\\/" "√" "\\\\//")
         (#\W "\\/\\/" "vv" "'//" "\\\\'" "\\^/" "(n)" "\\X/" "\\|/" "\\_|_/"
              "\\\\//\\\\//" "\\_:_/" "]I[" "UU" "Ш" "ɰ" "￦" "JL")
         (#\X "%" "><" "Ж" "}{" "ecks" "×" "*" ")(" "ex")
         (#\Y "j" "`/" "`(" "-/" "'/" "Ψ" "φ" "λ" "Ч" "¥")
         (#\Z "2" "≥" "~/_" "%" "ʒ" "7_"))))


; ok, so I'm being a masochist for not simply using R6RS or some other...
; I'm a gluton for punishment... :p
(define upper
  (let ((ups  "ABCDEFGHIJKLMNOPQRSTUVWXYZ")
        (lows (let* ((s "abcdefghijklmnopqrstuvwxyz") (sz (string-length s)))
                (let f ((i 0))
                  (if (= i sz) `()
                      (cons (cons (string-ref s i) i)
                            (f (+ 1 i))))))))
    (lambda (ls)
      (map (lambda (c) (let ((r (assoc c lows))) (if r (string-ref ups (cdr r)) c)))
           ls))))

(define random!
  (let ((seed 42))
    (lambda (upto)
      (let ((n (+ 3 (* 2 seed))))
        (set! seed (+ 1 (modulo n seed) seed))
        (modulo n upto)))))