feat: change up organisation

labs/cs2030s/Lab4/Action.java

@@ -0,0 +1,12 @@
+/**
+ * The Action interface that can be called
+ * on an object of type T to act.
+ * Contains a single abstract method call.
+ * CS2030S Lab 4
+ * AY22/23 Semester 1
+ * @author Yadunand Prem (10B)
+ */
+
+interface Action<T> {
+  void call(T item);
+}

labs/cs2030s/Lab4/Actionable.java

@@ -0,0 +1,13 @@
+/**
+ * The Actionable interface that can
+ * act when given an action.
+ * Contains a single abstract method act.
+ * CS2030S Lab 4
+ * AY22/23 Semester 1
+ * @author Yadunand Prem (10B)
+ */
+
+// act consumes the T and passes it to action, thus super
+interface Actionable<T> {
+  public void act(Action<? super T> action);
+}

labs/cs2030s/Lab4/Applicable.java

@@ -0,0 +1,14 @@
+/**
+ * The Applicable interface that can probably
+ * transform if given something that is
+ * probably an Immutator.
+ * Contains a single abstract method apply.
+ * CS2030S Lab 4
+ * AY22/23 Semester 1
+ * 
+ * @author Yadunand Prem (10B)
+ */
+
+interface Applicable<T> {
+  <R> Applicable<R> apply(Probably<? extends Immutator<? extends R, ? super T>> probablyImmutator);
+}

labs/cs2030s/Lab4/CS2030STest.java

@@ -0,0 +1,75 @@
+import java.net.URI;
+import java.util.List;
+import javax.tools.DiagnosticCollector;
+import javax.tools.SimpleJavaFileObject;
+import javax.tools.ToolProvider;
+import java.io.PrintStream;
+import java.io.ByteArrayOutputStream;
+
+class CS2030STest {
+
+  private static final String ANSI_RESET = "\u001B[0m";
+  private static final String ANSI_RED = "\u001B[31m";
+  private static final String ANSI_GREEN = "\u001B[32m";
+
+  public void expect(String test, Object output, Object expect) {
+    System.out.print(test);
+    if ((expect == null && output == null) || output.equals(expect)) {
+      System.out.println(".. " + ANSI_GREEN + "ok" + ANSI_RESET);
+    } else {
+      System.out.println(".. " + ANSI_RED + "failed" + ANSI_RESET);
+      System.out.println("  expected: " + expect);
+      System.out.println("  got this: " + output);
+    }
+  }
+  
+  public static String clean(String txt) {
+    String res = "";
+    for (int i=0; i<txt.length(); i++) {
+      if (txt.charAt(i) != '\r' && txt.charAt(i) != '\n') {
+        res += txt.charAt(i);
+      }
+    }
+    return res;
+  }
+  public void expectPrint(String test, Object expect, ByteArrayOutputStream baos, PrintStream old) {
+    System.out.flush();
+    System.setOut(old);
+    expect(test, CS2030STest.clean(baos.toString()), expect);
+  }
+
+  public void expectCompile(String test, String statement, boolean success) {
+    System.out.print(test);
+
+    class JavaSourceFromString extends SimpleJavaFileObject {
+      final String code;
+
+      JavaSourceFromString(String code) {
+        super(URI.create("string:///TempClass.java"), Kind.SOURCE);
+        this.code = "class TempClass {void foo(){" +  code + ";}}";
+      }
+
+      @Override
+      public CharSequence getCharContent(boolean ignoreEncodingErrors) {
+        return code;
+      }
+    }
+
+    boolean noError = ToolProvider
+        .getSystemJavaCompiler()
+        .getTask(null, null, new DiagnosticCollector<>(), null, null, 
+            List.of(new JavaSourceFromString(statement)))
+        .call();
+
+    if (noError != success) {
+      System.out.println(".. " + ANSI_RED + "failed" + ANSI_RESET);
+      if (!success) {
+        System.out.println("  expected compilation error but it compiles fine.");
+      } else {
+        System.out.println("  expected the statement to compile without errors but it does not.");
+      }
+    } else {
+      System.out.println(".. " + ANSI_GREEN + "ok" + ANSI_RESET);
+    }
+  }
+}

labs/cs2030s/Lab4/Immutator.java

@@ -0,0 +1,12 @@
+/**
+ * The Immutator interface that can transform
+ * to type T2, an object of type T1.
+ * Contains a single abstract method invoke.
+ * CS2030S Lab 4
+ * AY22/23 Semester 1
+ * @author Yadunand Prem (10B)
+ */
+
+interface Immutator<R, P> {
+  public R invoke(P param);
+}

labs/cs2030s/Lab4/Immutatorable.java

@@ -0,0 +1,13 @@
+/**
+ * The Immutatorable interface that can
+ * transform when given something that is
+ * Immutator.
+ * Contains a single abstract method transform.
+ * CS2030S Lab 4
+ * AY22/23 Semester 1
+ * @author Yadunand Prem (10B)
+ */
+
+interface Immutatorable<T> {
+  public <R> Immutatorable<R> transform(Immutator<? extends R, ? super T> immutator);
+}

labs/cs2030s/Lab4/Improbable.java

@@ -0,0 +1,15 @@
+/**
+ * A generic Immutator that takes in an object
+ * that is T and returns an object that is probably T.
+ * CS2030S Lab 4
+ * AY22/23 Semester 1
+ *
+ * @author Yadunand Prem (10B)
+ */
+
+class Improbable<T> implements Immutator<Probably<T>, T> {
+  @Override
+  public Probably<T> invoke(T param) {
+    return Probably.just(param);
+  }
+}

labs/cs2030s/Lab4/IsModEq.java

@@ -0,0 +1,27 @@
+/**
+ * A non-generic Immutator with parameter
+ * div and mod that takes in an integer val
+ * and return the boolean value by checking
+ * if the given value is equal to mod when
+ * divided by div.
+ * CS2030S Lab 4
+ * AY22/23 Semester 1
+ *
+ * @author Yadunand Prem (10B)
+ */
+
+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;
+  }
+}

labs/cs2030s/Lab4/Lab4.java

@@ -0,0 +1,247 @@
+import java.util.Scanner;
+import java.io.PrintStream;
+import java.io.ByteArrayOutputStream;
+
+/**
+ * The main class for CS2030S Lab 4.
+ *
+ * @author Wei Tsang
+   * @version CS2030S AY21/22 Semester 2
+ */
+class Lab4 {
+    
+  /**
+   * Inner class for testing.
+   */
+  static class Incr implements Immutator<Integer,Integer> {
+    public Integer invoke(Integer t1) {
+      return t1 + 1;
+    }
+  }
+  /**
+   * Inner class for testing.
+   */
+  static class Length implements Immutator<Integer,String> {
+    public Integer invoke(String t1) {
+      return t1.length();
+    }
+  }
+    
+  /**
+   * Helper method to clean a string from
+   * any newline.
+   *
+   * @param txt Input string.
+   * @return The cleaned string.
+   */
+  public static String clean(String txt) {
+    String res = "";
+    for (int i=0; i<txt.length(); i++) {
+      if (txt.charAt(i) != '\r' && txt.charAt(i) != '\n') {
+        res += txt.charAt(i);
+      }
+    }
+    return res;
+  }
+  
+  public static void main(String[] args) {
+    // Create a scanner to read from standard input.
+    Scanner sc = new Scanner(System.in);
+
+    // Read a single integer from the test file
+    // and then run the appropriate test case
+    switch (sc.nextInt()) {
+      case 1:
+        test1();
+        break;
+      case 2:
+        test2();
+        break;
+      case 3:
+        test3();
+        break;
+      case 4:
+        test4();
+        break;
+      case 5:
+        test5();
+        break;
+      case 6:
+        test6();
+        break;
+    }
+
+    // Clean up the scanner.
+    sc.close();
+  }
+  
+  /**
+   * Test #1.
+   */
+  public static void test1() {
+    PrintStream old = System.out;
+    ByteArrayOutputStream baos;
+    PrintStream ps;
+    
+    try {
+      baos = new ByteArrayOutputStream();
+      ps = new PrintStream(baos);
+      System.setOut(ps);
+      
+      new Print().call(17);
+      System.out.flush();
+      System.setOut(old);
+      
+      System.out.println(Lab4.clean(baos.toString()));
+    } catch(Exception e) {
+      System.out.println("Error occurred");
+    }
+    
+    try {
+      baos = new ByteArrayOutputStream();
+      ps = new PrintStream(baos);
+      System.setOut(ps);
+      
+      new Print().call("string");
+      System.out.flush();
+      System.setOut(old);
+      
+      System.out.println(Lab4.clean(baos.toString()));
+    } catch(Exception e) {
+      System.out.println("Error occurred");
+    }
+  }
+  
+  /**
+   * Test #2.
+   */
+  public static void test2() {
+    PrintStream old = System.out;
+    ByteArrayOutputStream baos;
+    PrintStream ps;
+    
+    try {
+      baos = new ByteArrayOutputStream();
+      ps = new PrintStream(baos);
+      System.setOut(ps);
+      
+      Probably.just(4).act(new Print());
+      System.out.flush();
+      System.setOut(old);
+      
+      System.out.println(Lab4.clean(baos.toString()));
+    } catch(Exception e) {
+      System.out.println("Error occurred");
+    }
+    
+    try {
+      baos = new ByteArrayOutputStream();
+      ps = new PrintStream(baos);
+      System.setOut(ps);
+      
+      Probably.just("string").act(new Print());
+      System.out.flush();
+      System.setOut(old);
+      
+      System.out.println(Lab4.clean(baos.toString()));
+    } catch(Exception e) {
+      System.out.println("Error occurred");
+    }
+    
+    try {
+      baos = new ByteArrayOutputStream();
+      ps = new PrintStream(baos);
+      System.setOut(ps);
+      
+      Probably.none().act(new Print());
+      System.out.flush();
+      System.setOut(old);
+      
+      System.out.println(Lab4.clean(baos.toString()));
+    } catch(Exception e) {
+      System.out.println("Error occurred");
+    }
+  }
+  
+  /**
+   * Test #3.
+   */
+  public static void test3() {
+    try {
+      System.out.println(new Incr().invoke(4).toString());
+      System.out.println(new Incr().invoke(new Incr().invoke(4)).toString());
+      System.out.println(new Length().invoke("string").toString());
+      System.out.println(new Incr().invoke(new Length().invoke("string")).toString());
+      
+      System.out.println(new Improbable<Integer>().invoke(1).toString());
+      System.out.println(new Improbable<String>().invoke(null).toString());
+      System.out.println(new Improbable<Integer>().invoke(1).transform(new Incr()).toString());
+      System.out.println(new Improbable<>().invoke(new Improbable<Integer>().invoke(1)).toString());
+    } catch(Exception e) {
+      System.out.println("Error occurred");
+    }
+  }
+  
+  /**
+   * Test #4.
+   */
+  public static void test4() {
+    try {
+      System.out.println(Probably.just(4).transform(new Incr()).toString());
+      System.out.println(Probably.just(4).transform(new Incr()).transform(new Incr()).toString());
+      System.out.println(Probably.just("string").transform(new Length()).toString());
+      System.out.println(Probably.just("string").transform(new Length()).transform(new Incr()).toString());
+      
+      System.out.println(Probably.<Integer>none().transform(new Incr()).toString());
+      System.out.println(Probably.<String>none().transform(new Length()).toString());
+      System.out.println(Probably.<String>just(null).transform(new Length()).transform(new Incr()).toString());
+    } catch(Exception e) {
+      System.out.println("Error occurred");
+    }
+  }
+  
+  /**
+   * Test #5.
+   */
+  public static void test5() {
+    Probably<Immutator<Integer,Integer>> justIncr = Probably.just(new Incr());
+    Probably<Immutator<Integer,String>> justLength = Probably.just(new Length());
+    Probably<Immutator<Integer,Integer>> noIncr = Probably.none();
+    Probably<Immutator<Integer,String>> noLength = Probably.none();
+    
+    try {
+      System.out.println(Probably.just(17).check(new IsModEq(3,2)).toString());
+      System.out.println(Probably.just(18).check(new IsModEq(3,2)).toString());
+      
+      System.out.println(Probably.just(16).transform(new Incr()).check(new IsModEq(3,2)).toString());
+      System.out.println(Probably.just("string").transform(new Length()).transform(new Incr()).transform(new Incr()).check(new IsModEq(3,2)).toString());
+      System.out.println(Probably.<Integer>just(null).check(new IsModEq(0,2)).toString());
+    } catch(Exception e) {
+      System.out.println("Error occurred");
+    }
+  }
+  
+  /**
+   * Test #6.
+   */
+  public static void test6() {
+    Probably<Immutator<Integer,Integer>> justIncr = Probably.just(new Incr());
+    Probably<Immutator<Integer,String>> justLength = Probably.just(new Length());
+    Probably<Immutator<Integer,Integer>> noIncr = Probably.none();
+    Probably<Immutator<Integer,String>> noLength = Probably.none();
+    
+    try {
+      System.out.println(Probably.just(17).apply(justIncr).toString());
+      System.out.println(Probably.<Integer>none().apply(justIncr).toString());
+      System.out.println(Probably.just(17).apply(noIncr).toString());
+      System.out.println(Probably.<Integer>none().apply(noIncr).toString());
+      
+      System.out.println(Probably.just("string").apply(justLength).toString());
+      System.out.println(Probably.<String>none().apply(justLength).toString());
+      System.out.println(Probably.just("string").apply(noLength).toString());
+      System.out.println(Probably.<String>none().apply(noLength).toString());
+    } catch(Exception e) {
+      System.out.println("Error occurred");
+    }
+  }
+}

labs/cs2030s/Lab4/MyTest.java

@@ -0,0 +1,60 @@
+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);
+  }
+}

labs/cs2030s/Lab4/Print.java

@@ -0,0 +1,17 @@
+/**
+ * A non-generic Action to print the String
+ * representation of the object.
+ * CS2030S Lab 4
+ * AY22/23 Semester 1
+ *
+ * @author Yadunand Prem (10B)
+ */
+
+class Print implements Action<Object> {
+
+  @Override
+  public void call(Object item) {
+    System.out.println(item);
+  }
+
+}

labs/cs2030s/Lab4/Probably.java

@@ -0,0 +1,134 @@
+/**
+ * This class implements something that
+ * probably is just a value but may be nothing.
+ * We will never return null in this class, but
+ * we may return something that contains nothing
+ * where the nothing is a null.
+ *
+ * @author Yadunand Prem (10B)
+ * @version CS2030S AY22/23 Semester 1
+ */
+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
+   * create this using the two public static method.
+   *
+   * @param value T
+   */
+  private Probably(T value) {
+    this.value = value;
+  }
+
+  /**
+   * It is probably nothing, no value inside.
+   *
+   * @param <T> type T
+   * @return The shared NOTHING.
+   */
+  public static <T> Probably<T> none() {
+    @SuppressWarnings("unchecked")
+    Probably<T> res = (Probably<T>) NONE;
+    return res;
+  }
+
+  /**
+   * It is probably just the given value.
+   * Unless the value is null, then nothing is
+   * given again.
+   *
+   * @param <T>   type T
+   *
+   * @param value Probably this is the value
+   *              unless it is null then we say
+   *              that there is no
+   * @return The given value or nothing but
+   *         never null.
+   */
+  public static <T> Probably<T> just(T value) {
+    if (value == null) {
+      return none();
+    }
+    return new Probably<>(value);
+  }
+
+  /**
+   * Check for equality between something that
+   * is probably a value but maybe nothing.
+   *
+   * @param obj The other value to be compared.
+   * @return True if the two values are equal,
+   *         false otherwise.
+   */
+  @Override
+  public boolean equals(Object obj) {
+    if (obj == this) {
+      return true;
+    }
+    if (obj instanceof Probably<?>) {
+      Probably<?> some = (Probably<?>) obj;
+      if (this.value == some.value) {
+        return true;
+      }
+      if (this.value == null || some.value == null) {
+        return false;
+      }
+      return this.value.equals(some.value);
+    }
+    return false;
+  }
+
+  /**
+   * String representation of something that
+   * is probably a value but maybe nothing.
+   *
+   * @return The string representation.
+   */
+  @Override
+  public String toString() {
+    if (this.value == null) {
+      return "<>";
+    } else {
+      return "<" + this.value.toString() + ">";
+    }
+  }
+
+  @Override
+  public void act(Action<? super T> action) {
+    if (this.value == null) {
+      return;
+    }
+    action.call(this.value);
+  }
+
+  public Probably<T> check(Immutator<Boolean, ? super T> eq) {
+    if (this.value == null) {
+      return none();
+    }
+    if (eq.invoke(this.value)) {
+      return this;
+    }
+    return none();
+  }
+
+  @Override
+  public <R> Probably<R> transform(Immutator<? extends R, ? super T> immutator) {
+    if (this.value == null) {
+      return none();
+    }
+    return just(immutator.invoke(this.value));
+  }
+
+  @Override
+  public <R> Probably<R> apply(Probably<? extends Immutator<? extends R, ? super T>> probablyImmutator) {
+    if (probablyImmutator.value != null) {
+      return this.transform(probablyImmutator.value);
+    }
+    return none();
+  }
+
+}

labs/cs2030s/Lab4/Test1.java

@@ -0,0 +1,32 @@
+import java.io.PrintStream;
+import java.io.ByteArrayOutputStream;
+
+class Test1 {
+  public static void main(String[] args) {
+    CS2030STest we = new CS2030STest();
+    
+    PrintStream old = System.out;
+    ByteArrayOutputStream baos;
+    PrintStream ps;
+    
+    baos = new ByteArrayOutputStream();
+    ps = new PrintStream(baos);
+    System.setOut(ps);
+    
+    new Print().call(17);
+    we.expectPrint("new Print().call(17)",
+                   "17",
+                   baos,
+                   old);
+    
+    baos = new ByteArrayOutputStream();
+    ps = new PrintStream(baos);
+    System.setOut(ps);
+    
+    new Print().call("string");
+    we.expectPrint("new Print().call(\"string\")",
+                   "string",
+                   baos,
+                   old);
+  }
+}

labs/cs2030s/Lab4/Test2.java

@@ -0,0 +1,42 @@
+import java.io.PrintStream;
+import java.io.ByteArrayOutputStream;
+
+class Test2 {
+  public static void main(String[] args) {
+    CS2030STest we = new CS2030STest();
+    
+    PrintStream old = System.out;
+    ByteArrayOutputStream baos;
+    PrintStream ps;
+    
+    baos = new ByteArrayOutputStream();
+    ps = new PrintStream(baos);
+    System.setOut(ps);
+    
+    Probably.just(4).act(new Print());
+    we.expectPrint("Probably.just(4).act(new Print())",
+                   "4",
+                   baos,
+                   old);
+    
+    baos = new ByteArrayOutputStream();
+    ps = new PrintStream(baos);
+    System.setOut(ps);
+    
+    Probably.just("string").act(new Print());
+    we.expectPrint("Probably.just(\"string\").act(new Print())",
+                   "string",
+                   baos,
+                   old);
+    
+    baos = new ByteArrayOutputStream();
+    ps = new PrintStream(baos);
+    System.setOut(ps);
+    
+    Probably.none().act(new Print());
+    we.expectPrint("Probably.none().act(new Print())",
+                   "",
+                   baos,
+                   old);
+  }
+}

labs/cs2030s/Lab4/Test3.java

@@ -0,0 +1,43 @@
+class Test3 {
+  public static void main(String[] args) {
+    CS2030STest we = new CS2030STest();
+    
+    class Incr implements Immutator<Integer, Integer> {
+      public Integer invoke(Integer t1) {
+        return t1 + 1;
+      }
+    }
+
+    class Length implements Immutator<Integer, String> {
+      public Integer invoke(String t1) {
+        return t1.length();
+      }
+    }
+    
+    we.expect("new Incr().invoke(4)",
+              new Incr().invoke(4).toString(),
+              "5");
+    we.expect("new Incr().invoke(new Incr().invoke(4))",
+              new Incr().invoke(new Incr().invoke(4)).toString(),
+              "6");
+    we.expect("new Length().invoke(\"string\")",
+              new Length().invoke("string").toString(),
+              "6");
+    we.expect("new Incr().invoke(new Length().invoke(\"string\"))",
+              new Incr().invoke(new Length().invoke("string")).toString(),
+              "7");
+
+    we.expect("new Improbable<>().invoke(1)",
+              new Improbable<Integer>().invoke(1).toString(),
+              "<1>");
+    we.expect("new Improbable<String>().invoke(null)",
+              new Improbable<String>().invoke(null).toString(),
+              "<>");
+    we.expect("new Improbable<Integer>().invoke(1).transform(new Incr())",
+              new Improbable<Integer>().invoke(1).transform(new Incr()).toString(),
+              "<2>");
+    we.expect("new Improbable<>().invoke(new Improbable<>().invoke(1))",
+              new Improbable<>().invoke(new Improbable<Integer>().invoke(1)).toString(),
+              "<<1>>");
+  }
+}

labs/cs2030s/Lab4/Test4.java

@@ -0,0 +1,40 @@
+class Test4 {
+  public static void main(String[] args) {
+    CS2030STest we = new CS2030STest();
+    
+    class Incr implements Immutator<Integer, Integer> {
+      public Integer invoke(Integer t1) {
+        return t1 + 1;
+      }
+    }
+
+    class Length implements Immutator<Integer, String> {
+      public Integer invoke(String t1) {
+        return t1.length();
+      }
+    }
+    
+    we.expect("Probably.just(4).transform(new Incr())",
+              Probably.just(4).transform(new Incr()).toString(),
+              "<5>");
+    we.expect("Probably.just(4).transform(new Incr()).transform(new Incr())",
+              Probably.just(4).transform(new Incr()).transform(new Incr()).toString(),
+              "<6>");
+    we.expect("Probably.just(\"string\").transform(new Length())",
+              Probably.just("string").transform(new Length()).toString(),
+              "<6>");
+    we.expect("Probably.just(\"string\").transform(new Length()).transform(new Incr())",
+              Probably.just("string").transform(new Length()).transform(new Incr()).toString(),
+              "<7>");
+              
+    we.expect("Probably.<Integer>none().transform(new Incr())",
+              Probably.<Integer>none().transform(new Incr()).toString(),
+              "<>");
+    we.expect("Probably.<String>none().transform(new Length())",
+              Probably.<String>none().transform(new Length()).toString(),
+              "<>");
+    we.expect("Probably.<String>just(null).transform(new Length()).transform(new Incr())",
+              Probably.<String>just(null).transform(new Length()).transform(new Incr()).toString(),
+              "<>");
+  }
+}

labs/cs2030s/Lab4/Test5.java

@@ -0,0 +1,34 @@
+class Test5 {
+  public static void main(String[] args) {
+    CS2030STest we = new CS2030STest();
+    
+    class Incr implements Immutator<Integer, Integer> {
+      public Integer invoke(Integer t1) {
+        return t1 + 1;
+      }
+    }
+
+    class Length implements Immutator<Integer, String> {
+      public Integer invoke(String t1) {
+        return t1.length();
+      }
+    }
+    
+    we.expect("Probably.just(17).check(new IsModEq(3,2)) // 17 % 3 is equal to 2",
+              Probably.just(17).check(new IsModEq(3, 2)).toString(),
+              "<17>");
+    we.expect("Probably.just(18).check(new IsModEq(3,2)) // 18 % 3 is not equal to 2",
+              Probably.just(18).check(new IsModEq(3,2)).toString(),
+              "<>");
+              
+    we.expect("Probably.just(16).transform(new Incr()).check(new IsModEq(3,2)) // 17 % 3 is not equal to 2",
+              Probably.just(16).transform(new Incr()).check(new IsModEq(3,2)).toString(),
+              "<17>");
+    we.expect("Probably.just(\"string\").transform(new Length()).check(new IsModEq(3,2))",
+              Probably.just("string").transform(new Length()).transform(new Incr()).transform(new Incr()).check(new IsModEq(3,2)).toString(),
+              "<8>");
+    we.expect("Probably.<Integer>just(null).check(new IsModEq(0,2))",
+              Probably.<Integer>just(null).check(new IsModEq(0,2)).toString(),
+              "<>");
+  }
+}

labs/cs2030s/Lab4/Test6.java

@@ -0,0 +1,48 @@
+class Test6 {
+  public static void main(String[] args) {
+    CS2030STest we = new CS2030STest();
+    
+    class Incr implements Immutator<Integer, Integer> {
+      public Integer invoke(Integer t1) {
+        return t1 + 1;
+      }
+    }
+
+    class Length implements Immutator<Integer, String> {
+      public Integer invoke(String t1) {
+        return t1.length();
+      }
+    }
+    
+    Probably<Immutator<Integer, Integer>> justIncr = Probably.just(new Incr());
+    Probably<Immutator<Integer, String>> justLength = Probably.just(new Length());
+    Probably<Immutator<Integer, Integer>> noIncr = Probably.none();
+    Probably<Immutator<Integer, String>> noLength = Probably.none();
+    
+    we.expect("Probably.just(17).<Integer>apply(justIncr)",
+              Probably.just(17).apply(justIncr).toString(),
+              "<18>");
+    we.expect("Probably.<Integer>none().<Integer>apply(justIncr)",
+              Probably.<Integer>none().apply(justIncr).toString(),
+              "<>");
+    we.expect("Probably.just(17).<Integer>apply(noIncr)",
+              Probably.just(17).apply(noIncr).toString(),
+              "<>");
+    we.expect("Probably.<Integer>none().<Integer>apply(noIncr)",
+              Probably.<Integer>none().apply(noIncr).toString(),
+              "<>");
+    
+    we.expect("Probably.just(\"string\").<Integer>apply(justLength)",
+              Probably.just("string").apply(justLength).toString(),
+              "<6>");
+    we.expect("Probably.<String>none().<Integer>apply(justLength)",
+              Probably.<String>none().apply(justLength).toString(),
+              "<>");
+    we.expect("Probably.just(\"string\").<Integer>apply(noLength)",
+              Probably.just("string").apply(noLength).toString(),
+              "<>");
+    we.expect("Probably.<String>none().<Integer>apply(noLength)",
+              Probably.<String>none().apply(noLength).toString(),
+              "<>");
+  }
+}

labs/cs2030s/Lab4/TestProbably.java

@@ -0,0 +1,58 @@
+class TestProbably {
+  public static void main(String[] args) {
+    CS2030STest we = new CS2030STest();
+    
+    we.expect("Probably.just(4)",
+              Probably.just(4).toString(),
+              "<4>");
+    we.expect("Probably.just(Probably.just(0))",
+              Probably.just(Probably.just(0)).toString(),
+              "<<0>>");
+    we.expect("Probably.just(Probably.just(Probably.just(\"null\")))",
+              Probably.just(Probably.just(Probably.just("null"))).toString(),
+              "<<<null>>>");
+    we.expect("Probably.just(Probably.just(Probably.none()))",
+              Probably.just(Probably.just(Probably.none())).toString(),
+              "<<<>>>");
+    we.expect("Probably.just(Probably.just(null))",
+              Probably.just(Probably.just(null)).toString(),
+              "<<>>");
+              
+    we.expect("Probably.just(4).equals(Probably.just(4))",
+              Probably.just(4).equals(Probably.just(4)),
+              true);
+    we.expect("Probably.just(4).equals(4)",
+              Probably.just(4).equals(4),
+              false);
+    we.expect("Probably.just(Probably.just(0)).equals(Probably.just(0))",
+              Probably.just(Probably.just(0)).equals(Probably.just(0)),
+              false);
+    we.expect("Probably.just(Probably.just(0)).equals(Probably.just(Probably.just(0)))",
+              Probably.just(Probably.just(0)).equals(Probably.just(Probably.just(0))),
+              true);
+              
+    we.expect("Probably.just(\"string\")",
+              Probably.just("string").toString(),
+              "<string>");
+              
+    we.expect("Probably.just(\"string\").equals(Probably.just(4))",
+              Probably.just("string").equals(Probably.just(4)),
+              false);
+    we.expect("Probably.just(\"string\").equals(Probably.just(\"null\"))",
+              Probably.just("string").equals(Probably.just("null")),
+              false);
+              
+    we.expect("Probably.just(null)",
+              Probably.just(null).toString(),
+              "<>");
+    we.expect("Probably.none()",
+              Probably.none().toString(),
+              "<>");
+    we.expect("Probably.none().equals(Probably.just(null))",
+              Probably.none().equals(Probably.just(null)),
+              true);
+    we.expect("Probably.none() == Probably.just(null)",
+              Probably.none() == Probably.just(null),
+              true);
+  }
+}

labs/cs2030s/Lab4/inputs/Lab4.1.in

@@ -0,0 +1 @@
+1

labs/cs2030s/Lab4/inputs/Lab4.2.in

@@ -0,0 +1 @@
+2

labs/cs2030s/Lab4/inputs/Lab4.3.in

@@ -0,0 +1 @@
+3

labs/cs2030s/Lab4/inputs/Lab4.4.in

@@ -0,0 +1 @@
+4

labs/cs2030s/Lab4/inputs/Lab4.5.in

@@ -0,0 +1 @@
+5

labs/cs2030s/Lab4/inputs/Lab4.6.in

@@ -0,0 +1 @@
+6

labs/cs2030s/Lab4/outputs/Lab4.1.out

@@ -0,0 +1,2 @@
+17
+string

labs/cs2030s/Lab4/outputs/Lab4.2.out

@@ -0,0 +1,3 @@
+4
+string
+

labs/cs2030s/Lab4/outputs/Lab4.3.out

@@ -0,0 +1,8 @@
+5
+6
+6
+7
+<1>
+<>
+<2>
+<<1>>

labs/cs2030s/Lab4/outputs/Lab4.4.out

@@ -0,0 +1,7 @@
+<5>
+<6>
+<6>
+<7>
+<>
+<>
+<>

labs/cs2030s/Lab4/outputs/Lab4.5.out

@@ -0,0 +1,5 @@
+<17>
+<>
+<17>
+<8>
+<>

labs/cs2030s/Lab4/outputs/Lab4.6.out

@@ -0,0 +1,8 @@
+<18>
+<>
+<>
+<>
+<6>
+<>
+<>
+<>