27 — Game: guessing a hidden set of colours

The computer hides three colours and you name three. It tells you only how many you got, never which ones, so finding them means changing one answer at a time and watching the number move.

#Steps

1. Choose the hidden colours. Shuffle the list and take the first of it, three times over:

   set colors to list of red, blue, green, yellow
   set answer to an empty list
   repeat 3 times
       shuffle colors
       append the first of colors to answer
   end
   show answer joined by comma
   

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   Printing the answer is how you check the program while building it. Delete that last line once it works.

2. One try takes three colours, keeps them in a list, and counts how many of them are in the hidden set:

   set answer to list of red, blue, green
   set right to 0
   set guess to an empty list
   repeat 3 times
       ask choice What colour?
       append choice to guess
       if answer contains choice
           add 1 to right
       end
   end
   show guess joined by comma
   show right
   

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3. Winning is that one count:

   set right to 3
   if right equals 3
       show you found them all
   end
   

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4. Count the tries down, and show the answer when they run out:

   set lives to 5
   subtract 1 from lives
   if lives equals 0
       show out of tries
   end
   

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5. All of it:

   set colors to list of red, blue, green, yellow
   set answer to an empty list
   repeat 3 times
       shuffle colors
       append the first of colors to answer
   end
   set lives to 5
   repeat forever
       set right to 0
       set guess to an empty list
       repeat 3 times
           ask choice What colour?
           append choice to guess
           if answer contains choice
               add 1 to right
           end
       end
       show guess joined by comma
       show how many of them are hidden
       show right
       if right equals 3
           show you found them all
           stop
       end
       subtract 1 from lives
       if lives equals 0
           show out of tries
           show answer joined by comma
           stop
       end
   end
   

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   Position is not checked. It only counts whether a colour is in there, so naming the same colour twice counts twice. Real Mastermind also says how many are in the right place, and that needs a loop that knows which position it is at — something sentence syntax does not have yet.

#Try it yourself

Use five colours and six tries. Count for yourself which of the two changes makes it harder.

#What you learned

• Shuffling and taking the first, several times over, makes a random set.
• A value taken out of one list goes straight into another.
• "How many did I get" is one counting name and one contains.
• The whole game has no quotes, no brackets and no equals sign.