Removed while loops

core/shared/src/main/scala/doodle/core/Transform.scala

@@ -17,6 +17,8 @@
 package doodle
 package core
 
+import scala.annotation.tailrec
+
 /** Representation of an affine transformation as an augmented matrix. */
 final case class Transform(elements: Array[Double]) {
   def apply(point: Point): Point = {
@@ -70,17 +72,20 @@ final case class Transform(elements: Array[Double]) {
   }
 
   override def equals(that: Any): Boolean = {
+    @scala.annotation.tailrec
+    def checkEquality(
+        thisElements: Array[Double],
+        otherElements: Array[Double],
+        index: Int
+    ): Boolean = {
+      if (index >= thisElements.length) true
+      else if (thisElements(index) != otherElements(index)) false
+      else checkEquality(thisElements, otherElements, index + 1)
+    }
+
     that.isInstanceOf[Transform] && {
       val other = that.asInstanceOf[Transform]
-      var i = 0
-      var isEqual = true
-      while (i < elements.length) {
-        if (this.elements(i) != other.elements(i))
-          isEqual = false
-
-        i = i + 1
-      }
-      isEqual
+      checkEquality(this.elements, other.elements, 0)
     }
   }
 

golden/src/test/scala/doodle/golden/Golden.scala

@@ -79,19 +79,21 @@ trait Golden { self: FunSuite =>
   }
 
   def pixelAbsoluteError(a: Int, b: Int): Int = {
-    var error = 0
-    var i = 0
-    while (i < 4) {
-      val shift = i * 8
-      val mask = 0x000000ff << shift
-      val aValue = (a & mask) >> shift
-      val bValue = (b & mask) >> shift
-
-      error = error + Math.abs(aValue - bValue)
-
-      i = i + 1
+    @scala.annotation.tailrec
+    def calculateError(i: Int, acc: Int): Int = {
+      if (i >= 4) acc
+      else {
+        val shift = i * 8
+        val mask = 0x000000ff << shift
+        val aValue = (a & mask) >> shift
+        val bValue = (b & mask) >> shift
+
+        val newError = acc + Math.abs(aValue - bValue)
+        calculateError(i + 1, newError)
+      }
     }
-    error
+
+    calculateError(0, 0)
   }
 
   def absoluteError(

java2d/src/main/scala/doodle/java2d/effect/Java2DPanel.scala

@@ -126,8 +126,7 @@ final class Java2DPanel(frame: Frame)(implicit runtime: IORuntime)
         Java2d.render(gc, reified, tx)
 
         // Draw remaining images, redrawing *before* each image
-        var i = 0
-        while (i < pictures.size) {
+        pictures.foreach { case (bb, reified) =>
           frame.redraw match {
             case Redraw.ClearToBackground =>
               frame.background.foreach { c =>
@@ -140,7 +139,6 @@ final class Java2DPanel(frame: Frame)(implicit runtime: IORuntime)
               gc.fillRect(0, 0, getWidth(), getHeight())
           }
 
-          val (bb, reified) = pictures(i)
           val tx = Java2d.transform(
             bb,
             getWidth.toDouble,
@@ -149,9 +147,8 @@ final class Java2DPanel(frame: Frame)(implicit runtime: IORuntime)
           )
 
           Java2d.render(gc, reified, tx)
-
-          i = i + 1
         }
+
     }
   }