Teachpacks for How to Design Programs

# Mastermind

### master.ss

The teachpack `master.ss` provides the operation `master`. It implements a GUI for playing a simple master mind-like game. The player clicks on two colors and the program responds with an answer that indicates how many colors and places were correct.

The function `master` consumes the function `check-guess`, which is the key component of TeachMasterMind. The function `check-guess` consumes the two colors that the player guessed and the two players that the master chose (randomly at the beginning of the game). It compares the colors and produces an appropriate symbol.

The teachpack provides only one operation:

- `master : check-guess -> symbol;`
  It prompts the user for two colors (symbols) and uses `check-guess` to play mastermind.
  If the guesses completely match the set-up, `check-guess` must return `'PerfectGuess`; otherwise it must return a different, informative symbol.