add conditional

Lab6/And.java

@@ -1,22 +1,25 @@
 class And implements Cond {
   private Cond lVal;
   private Cond rVal;
-  
+
   public And(Cond lVal, Cond rVal) {
     this.lVal = lVal;
     this.rVal = rVal;
   }
-  
+
   @Override
   public boolean eval() {
-    return this.lVal.eval() && this.rVal.eval();
+    if (!this.lVal.eval()) {
+      return false;
+    }
+    return this.rVal.eval();
   }
-  
+
   @Override
   public String toString() {
     return "(" + this.lVal + " & " + this.rVal + ")";
   }
-  
+
   @Override
   public Cond neg() {
     return new Or(lVal.neg(), rVal.neg());

Lab6/Bool.java

@@ -1,22 +1,23 @@
 import cs2030s.fp.Constant;
+import cs2030s.fp.Memo;
 
 class Bool implements Cond {
-  private Boolean val;
-  
+  private Memo<Boolean> val;
+
   public Bool(Constant<Boolean> val) {
-    this.val = val.init();
+    this.val = Memo.from(val);
   }
-  
+
   @Override
   public boolean eval() {
-    return this.val;
+    return this.val.get();
   }
-  
+
   @Override
   public String toString() {
     return this.val.toString().substring(0, 1);
   }
-  
+
   @Override
   public Cond neg() {
     return new Not(this);

Lab6/Or.java

@@ -1,22 +1,25 @@
 class Or implements Cond {
   private Cond lVal;
   private Cond rVal;
-  
+
   public Or(Cond lVal, Cond rVal) {
     this.lVal = lVal;
     this.rVal = rVal;
   }
-  
+
   @Override
   public boolean eval() {
-    return this.lVal.eval() || this.rVal.eval();
+    if (this.lVal.eval()) {
+      return true;
+    }
+    return this.rVal.eval();
   }
-  
+
   @Override
   public String toString() {
     return "(" + this.lVal + " | " + this.rVal + ")";
   }
-  
+
   @Override
   public Cond neg() {
     return new And(lVal.neg(), rVal.neg());

Lab6/cs2030s/fp/Memo.java

@@ -28,6 +28,10 @@ public class Memo<T> extends Lazy<T> {
     return result;
   }
 
+  public <R, S> Memo<R> combine(Memo<? extends S> other, Combiner<? extends R, ? super T, ? super S> combiner) {
+    return Memo.<R>from(() -> combiner.combine(this.get(), other.get()));
+  }
+
   @Override
   public <R> Memo<R> transform(Immutator<? extends R, ? super T> f) {
     return Memo.<R>from(() -> f.invoke(this.get()));