/** Find which words, when you reverse their letters, or their phonemes, make
    another word.

    This generates two lists:

    1. Words that are also words when spelled backwards
    2. Words that are also words when the phonemes are spoken in reverse order.

    This is in response to a Twitter query:
    https://x.com/itsnotmyfault01/status/1833641657348051377
*/

word2phon = new dict
phon2word = new dict

// This uses the CMU pronunciation dictionary
// http://www.speech.cs.cmu.edu/cgi-bin/cmudict

// Specifically this file which you'll want to download
// https://svn.code.sf.net/p/cmusphinx/code/trunk/cmudict/cmudict-0.7b
// (you can replace the file: URL below with that but it'll fetch every time)

LINE:
for line = lines["file:/home/eliasen/prog/mobydict/mpron/cmupronunciation.txt"]
{
   if line =~ %r/^\s*;;;/   // Skip comments
      next LINE

   if [word, phonemes] = line =~ %r/(.*?)  (.*)/
   {
      word = trim[word]
      phonemes = trim[phonemes]
      phonemes =~ %s/\d//g       // Remove stresses (0,1,2)
      word2phon@word = phonemes
      phon2word@phonemes = word
   }
}

println["Words that are also words when spelled backwards:"]
for [word, phonemes] = sort[word2phon, byColumn[0]]
{
   revword = reverse[word]
   w2 = word2phon@revword
   if w2 != undef          // Is there a word spelled backward from this word?
   {
      revphonemes = word2phon@revword
      println["$word ($phonemes), $revword ($revphonemes)"]
   }
}

println[]

println["Words that are also words when the phonemes are spoken in reverse order."]
for [word, phonemes] = sort[word2phon, byColumn[0]]
{
   revphon = join[" ", reverse[split[%r/\s+/, phonemes]]]  // Reverse phonemes
   w2 = phon2word@revphon
   if w2 != undef    // Is there a word with phonemes reversed from this word?
      println["$word, $w2, $phonemes"]
}