feat: implement feedback

Proj2.hs

@@ -11,6 +11,9 @@ module Proj2
 where
 
 type GameState = ()
+import Data.List
+import Data.Set qualified as S
+
 
 data Note = A | B | C | D | E | F | G
   deriving (Eq, Show, Ord)
@@ -58,7 +61,22 @@ toPitch [note, octave] = Pitch <$> charToNote note <*> charToOctave octave
 toPitch _ = Nothing
 
 feedback :: [Pitch] -> [Pitch] -> (Int, Int, Int)
-feedback _ _ = (0, 0, 0)
+feedback target guess = (length correctPitches, correctNotes, correctOctaves)
+  where
+    targetSet = S.fromList target
+    guessSet = S.fromList guess
+
+    correctPitches = S.intersection targetSet guessSet
+    newTarget = S.difference targetSet correctPitches
+    newGuess = S.difference guessSet correctPitches
+
+    targetNoteSet = S.map note newTarget
+    guessNoteSet = S.map note newGuess
+    targetOctaveSet = S.map octave newTarget
+    guessOctaveSet = S.map octave newGuess
+
+    correctNotes = length $ S.intersection targetNoteSet guessNoteSet
+    correctOctaves = length $ S.intersection targetOctaveSet guessOctaveSet
 
 -- implement me
 initialGuess :: ([Pitch], GameState)