Merge pull request fpinscala#419 from x7c1/refactor-candy-answer

Simplify answer to exercise 6.11
dr0pi · Jun 26, 2015 · 5166981 · 5166981
2 parents b118cfd + 70cf952
commit 5166981
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Showing 2 changed files with 12 additions and 6 deletions.
diff --git a/answerkey/state/11.answer.scala b/answerkey/state/11.answer.scala
@@ -5,16 +5,19 @@ case object Turn extends Input
 case class Machine(locked: Boolean, candies: Int, coins: Int)
 
 object Candy {
-  def simulateMachine(inputs: List[Input]): State[Machine, (Int, Int)] = for {
-    _ <- sequence(inputs.map(i => modify((s: Machine) => (i, s) match {
+  def update = (i: Input) => (s: Machine) =>
+    (i, s) match {
       case (_, Machine(_, 0, _)) => s
       case (Coin, Machine(false, _, _)) => s
       case (Turn, Machine(true, _, _)) => s
       case (Coin, Machine(true, candy, coin)) =>
         Machine(false, candy, coin + 1)
       case (Turn, Machine(false, candy, coin)) =>
         Machine(true, candy - 1, coin)
-    })))
+    }
+
+  def simulateMachine(inputs: List[Input]): State[Machine, (Int, Int)] = for {
+    _ <- sequence(inputs map (modify[Machine] _ compose update))
     s <- get
   } yield (s.coins, s.candies)
 }
diff --git a/answers/src/main/scala/fpinscala/state/State.scala b/answers/src/main/scala/fpinscala/state/State.scala
@@ -222,16 +222,19 @@ case object Turn extends Input
 case class Machine(locked: Boolean, candies: Int, coins: Int)
 
 object Candy {
-  def simulateMachine(inputs: List[Input]): State[Machine, (Int, Int)] = for {
-    _ <- sequence(inputs.map(i => modify((s: Machine) => (i, s) match {
+  def update = (i: Input) => (s: Machine) =>
+    (i, s) match {
       case (_, Machine(_, 0, _)) => s
       case (Coin, Machine(false, _, _)) => s
       case (Turn, Machine(true, _, _)) => s
       case (Coin, Machine(true, candy, coin)) =>
         Machine(false, candy, coin + 1)
       case (Turn, Machine(false, candy, coin)) =>
         Machine(true, candy - 1, coin)
-    })))
+    }
+
+  def simulateMachine(inputs: List[Input]): State[Machine, (Int, Int)] = for {
+    _ <- sequence(inputs map (modify[Machine] _ compose update))
     s <- get
   } yield (s.coins, s.candies)
 }