gistfile1.txt

; Generate random output from input seed-text, using a Markov chain.

MAXGEN = 10000
NONWORD = "\n"
HEAD = NONWORD, NONWORD
prefix := HEAD
statetab = HashMap with-factory: (= Vector)

to start
  "The program entry point. Procedure names should be verbs, hence 'main' is out."
  build-chain-from stdin
  add NONWORD ; to mark the end of the Markov chain
  generate-markov-text MAXGEN

to build-chain-from input
  "Build the Markov chain from the given input stream."
  for word in input words
    add word

to add word
  "Add a suffix word to the Markov for the current prefix."
  statetab prefix push word
  prefix pop push word

to generate n-words
  "Generate at most n-words of output text from the Markov chain,
   or until we hit a NONWORD."
  prefix clear add-all HEAD
  for i in 0 .. n-words
    word = statetab prefix random-element
    if word is NONWORD
      return
    stdout println word
    prefix pop push word