wip

Lab4/Applicable.java

@@ -8,5 +8,9 @@
  * CS2030S Lab 4
  * AY22/23 Semester 1
  *
- * @author Put Your Name (Lab Group)
+ * @author Yadunand Prem (10B)
  */
+
+interface Applicable<T> {
+    <R> Applicable<R> apply(Immutator<Probably<R>, Probably<T>> immutator);
+}

Lab4/Immutatorable.java

@@ -12,5 +12,5 @@
  */
 
 interface Immutatorable<T> {
-  public <R> R transform(Immutator<R, ? super T> immutator);
+  public <R> Immutatorable<R> transform(Immutator<R, T> immutator);
 }

Lab4/IsModEq.java

@@ -10,3 +10,19 @@
  *
  * @author Put Your Name (Lab Group)
  */
+
+class IsModEq implements Immutator<Boolean, Integer> {
+
+    private int div;
+    private int check;
+
+    public IsModEq(int div, int check) {
+        this.div = div;
+        this.check = check;
+    }
+
+    @Override
+    public Boolean invoke(Integer val) {
+        return val % div == check;
+    }
+}

Lab4/MyTest.java

@@ -1,10 +1,60 @@
-class MyTest {
-  public static void main(String[] args) { 
-    Probably<Integer> maybeInt = Probably.just(10);
-    System.out.println( maybeInt.transform(new Immutator<Integer,Integer>() {
-      public Integer invoke(Integer t1) {
-        return t1+1;
-      }
-    }));
+interface Function<T, R> {
+  R apply(T t);
+}
+
+interface Functor<T, F extends Functor<?, ?>> {
+  <R> F map(Function<T, R> f);
+}
+
+class Identity<T> implements Functor<T, Identity<?>> {
+  private final T value;
+
+  public Identity(T value) {
+    this.value = value;
+  }
+
+  @Override
+  public <R> Identity<R> map(Function<T, R> f) {
+    final R result = f.apply(this.value);
+    return new Identity<>(result);
+  }
+
+}
+
+class Incr implements Immutator<Integer, Integer> {
+
+  @Override
+  public Integer invoke(Integer param) {
+    return param + 1;
+  }
+}
+
+class Length implements Immutator<Integer, String> {
+
+  @Override
+  public Integer invoke(String param) {
+    return param.length();
+  }
+}
+
+class Print implements Action<Object> {
+
+  @Override
+  public void call(Object item) {
+    System.out.println(item);
+
+  }
+
+}
+
+class MyTest {
+
+  public static void main(String[] args) {
+    Probably<Integer> maybeInt = Probably.just(10);
+    maybeInt.act(new Print());
+    System.out.println(Probably.just(2030).check(new IsModEq(0, 2)));
+
+    Identity<String> idString = new Identity<>("abc");
+    Identity<Integer> idInt = idString.map(String::length);
   }
 }

Lab4/Probably.java

@@ -8,14 +8,14 @@
  * @author Yadunand Prem (10B)
  * @version CS2030S AY22/23 Semester 1
  */
-class Probably<T> implements Actionable<T>, Immutatorable<T> {
+class Probably<T> implements Actionable<T>, Immutatorable<T>, Applicable<T> {
   private final T value;
 
   private static final Probably<?> NONE = new Probably<>(null);
-  
+
   /**
    * Private constructor, can only be invoked inside.
-   * This is called a factory method.  We can only
+   * This is called a factory method. We can only
    * create this using the two public static method.
    *
    * @return The shared NOTHING.
@@ -23,7 +23,7 @@ class Probably<T> implements Actionable<T>, Immutatorable<T> {
   private Probably(T value) {
     this.value = value;
   }
-  
+
   /**
    * It is probably nothing, no value inside.
    *
@@ -34,7 +34,7 @@ class Probably<T> implements Actionable<T>, Immutatorable<T> {
     Probably<T> res = (Probably<T>) NONE;
     return res;
   }
-  
+
   /**
    * It is probably just the given value.
    * Unless the value is null, then nothing is
@@ -42,7 +42,7 @@ class Probably<T> implements Actionable<T>, Immutatorable<T> {
    *
    * @param value Probably this is the value
    *              unless it is null then we say
-   *              that there is no 
+   *              that there is no
    * @return The given value or nothing but
    *         never null.
    */
@@ -52,7 +52,7 @@ class Probably<T> implements Actionable<T>, Immutatorable<T> {
     }
     return new Probably<>(value);
   }
-  
+
   /**
    * Check for equality between something that
    * is probably a value but maybe nothing.
@@ -78,7 +78,7 @@ class Probably<T> implements Actionable<T>, Immutatorable<T> {
     }
     return false;
   }
-  
+
   /**
    * String representation of something that
    * is probably a value but maybe nothing.
@@ -102,10 +102,33 @@ class Probably<T> implements Actionable<T>, Immutatorable<T> {
     action.call(this.value);
   }
 
-  @Override
-  public <R> Probably<R> transform(Immutator<Probably<R>, ? super T> immutator) {
-    return immutator.invoke(this.value);
+  public Probably<T> check(IsModEq eq) {
+    if (this.value == null) {
+      return none();
+    }
+    if (this.value instanceof Integer) {
+      Integer val = (Integer) this.value;
+      if (eq.invoke(val)) {
+        return this;
+      }
+    }
+    return none();
   }
 
+  @Override
+  public <R> Probably<R> transform(Immutator<R, T> immutator) {
+    if (this.value == null) {
+      return none();
+    }
+    return just(immutator.invoke(this.value));
+  }
+
+  @Override
+  public <R> Probably<R> apply(Immutator<Probably<R>, Probably<T>> immutator) {
+    if (this.value == null) {
+      return none();
+    }
+    return immutator.invoke(this);
+  }
 
 }