PesistentHashMap compiles

src/main/java/com/logicalpractice/persistentcollections/PersistentList.java

@@ -8,7 +8,7 @@
  */
 public interface PersistentList<T> extends List<T>, RandomAccess {
 
-   PersistentList<T> withSet(int i, T val);
+   PersistentList<T> with(int i, T val);
 
    PersistentList<T> withAppended(T val);
 

src/main/java/com/logicalpractice/persistentcollections/PersistentMap.java

@@ -0,0 +1,13 @@
+package com.logicalpractice.persistentcollections;
+
+import java.util.Map;
+
+/**
+ *
+ */
+public interface PersistentMap<K,V> extends Map<K,V> {
+
+   PersistentMap<K,V> with(K key, V value);
+
+   TransientMap<K,V> toTransientMap();
+}

src/main/java/com/logicalpractice/persistentcollections/PersistentTreeList.java

@@ -54,7 +54,7 @@ public Object[] arrayFor(int i) {
    }
 
    @Override
-   public PersistentList<T> withSet(int i, T val) {
+   public PersistentList<T> with(int i, T val) {
       if (i >= 0 && i < cnt) {
          if (i >= tailoff()) {
             Object[] newTail = new Object[tail.length];

src/main/java/com/logicalpractice/persistentcollections/TransientMap.java

@@ -0,0 +1,11 @@
+package com.logicalpractice.persistentcollections;
+
+import java.util.Map;
+
+/**
+ *
+ */
+public interface TransientMap<K,V> extends Map<K,V> {
+
+   PersistentMap<K,V> toPersistentMap();
+}

src/main/java/com/logicalpractice/persistentcollections/Util.java

@@ -0,0 +1,15 @@
+package com.logicalpractice.persistentcollections;
+
+/**
+ *
+ */
+public class Util {
+
+   public static boolean equals(Object lhs, Object rhs){
+      return (lhs == rhs) || (lhs != null && lhs.equals(rhs));
+   }
+
+   public static int hashCode(Object o) {
+      return o == null ? 1 : o.hashCode();
+   }
+}

src/test/java/com/logicalpractice/persistentcollections/UtilTest.java

@@ -0,0 +1,33 @@
+package com.logicalpractice.persistentcollections;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+/**
+ *
+ */
+public class UtilTest {
+
+   @Test
+   public void testEquals() throws Exception {
+      assertTrue(Util.equals(null, null));
+      assertTrue(Util.equals("Thing", "Thing")); // same reference
+
+      assertFalse(Util.equals("Thing", null));
+      assertFalse(Util.equals(null, "null"));
+   }
+
+   @SuppressWarnings("RedundantStringConstructorCall")
+   @Test
+   public void testEquals2() throws Exception {
+      assertTrue(Util.equals(new String("Thing"), new String("Thing"))); // not same reference
+      assertFalse(Util.equals(new String("foo"), new String("bar")));
+   }
+
+   @Test
+   public void testHashCode() throws Exception {
+
+   }
+}