Taken from Haskell Programming From First Principles (aka The Haskell Book) Chapter 13
In case anyone is not familiar with the game, Hangman is a game with 2 (in this case) player. The first player picks a word at random and the second has to guess that word letter-by-letter. Typically game also involves drawing an empty gallows pole and each incorrect guess adds a body part to the gallows starting at the head, then body, one arm, then the other and so on until there is second player has guessed the word (win) or all the body parts have been drawn (lose). The second player can make as many correct guesses as is needed to fully 'expose' the word; each correct guess exposes a part of the target word.