Collection functions

vavr/generator/Generator.scala

@@ -2519,7 +2519,7 @@ def generateTestClasses(): Unit = {
               @$test
               public void shouldCreate${func}From${i}Pairs() {
                 $MapType<Integer, Integer> map = $func(${(1 to i).gen(j => s"$j, ${j*2}")(", ")});
-                ${(1 to i).gen(j => s"assertThat(map.apply($j)).isEqualTo(${j*2});")("\n")}
+                ${(1 to i).gen(j => s"assertThat(map.get($j).get()).isEqualTo(${j*2});")("\n")}
               }
             """
           })("\n\n")}

vavr/src/main/java/io/vavr/collection/IndexedSeq.java

@@ -71,6 +71,21 @@ static <T> IndexedSeq<T> narrow(IndexedSeq<? extends T> indexedSeq) {
     @Override
     IndexedSeq<T> asJavaMutable(Consumer<? super java.util.List<T>> action);
 
+    @Override
+    default PartialFunction<Integer, T> asPartialFunction() throws IndexOutOfBoundsException {
+        return new PartialFunction<Integer, T>() {
+            private static final long serialVersionUID = 1L;
+            @Override
+            public T apply(Integer index) {
+                return get(index);
+            }
+            @Override
+            public boolean isDefinedAt(Integer index) {
+                return 0 <= index && index < length();
+            }
+        };
+    }
+
     @Override
     <R> IndexedSeq<R> collect(PartialFunction<? super T, ? extends R> partialFunction);
 
@@ -177,11 +192,6 @@ default int indexOfSlice(Iterable<? extends T> that, int from) {
     @Override
     IndexedSeq<T> intersperse(T element);
 
-    @Override
-    default boolean isDefinedAt(Integer index) {
-        return 0 <= index && index < length();
-    }
-
     @Override
     default T last() {
         if (isEmpty()) {

vavr/src/main/java/io/vavr/collection/LinearSeq.java

@@ -70,6 +70,22 @@ static <T> LinearSeq<T> narrow(LinearSeq<? extends T> linearSeq) {
     @Override
     LinearSeq<T> asJavaMutable(Consumer<? super java.util.List<T>> action);
 
+    @Override
+    default PartialFunction<Integer, T> asPartialFunction() throws IndexOutOfBoundsException {
+        return new PartialFunction<Integer, T>() {
+            private static final long serialVersionUID = 1L;
+            @Override
+            public T apply(Integer index) {
+                return get(index);
+            }
+            @Override
+            public boolean isDefinedAt(Integer index) {
+                // we can't use length() because of infinite long sequences
+                return 0 <= index && drop(index).nonEmpty();
+            }
+        };
+    }
+
     @Override
     <R> LinearSeq<R> collect(PartialFunction<? super T, ? extends R> partialFunction);
 
@@ -160,12 +176,6 @@ default int indexWhere(Predicate<? super T> predicate, int from) {
     @Override
     LinearSeq<T> intersperse(T element);
 
-    @Override
-    default boolean isDefinedAt(Integer index) {
-        // we can't use length() because of infinite long sequences
-        return 0 <= index && drop(index).nonEmpty();
-    }
-
     @Override
     default int lastIndexOfSlice(Iterable<? extends T> that, int end) {
         Objects.requireNonNull(that, "that is null");

vavr/src/main/java/io/vavr/collection/Map.java

@@ -87,15 +87,13 @@
  * <li>{@link #transform(Function)}</li>
  * <li>{@link #unzip(BiFunction)}</li>
  * <li>{@link #unzip3(BiFunction)}</li>
- * <li>{@link #withDefault(Function)}</li>
- * <li>{@link #withDefaultValue(Object)}</li>
  * </ul>
  *
  * @param <K> Key type
  * @param <V> Value type
  * @author Daniel Dietrich, Ruslan Sennov
  */
-public interface Map<K, V> extends Traversable<Tuple2<K, V>>, PartialFunction<K, V>, Serializable {
+public interface Map<K, V> extends Traversable<Tuple2<K, V>>, Serializable {
 
     long serialVersionUID = 1L;
 
@@ -141,9 +139,26 @@ static <K, V> Tuple2<K, V> entry(K key, V value) {
         return Tuple.of(key, value);
     }
 
-    @Override
-    default V apply(K key) {
-        return get(key).getOrElseThrow(() -> new NoSuchElementException(String.valueOf(key)));
+    /**
+     * Turns this {@code Map} into a {@link PartialFunction} which is defined at a specific index, if this {@code Map}
+     * contains the given key. When applied to a defined key, the partial function will return
+     * the value of this {@code Map} that is associated with the key.
+     *
+     * @return a new {@link PartialFunction}
+     * @throws NoSuchElementException when a non-existing key is applied to the partial function
+     */
+    default PartialFunction<K, V> asPartialFunction() throws IndexOutOfBoundsException {
+        return new PartialFunction<K, V>() {
+            private static final long serialVersionUID = 1L;
+            @Override
+            public V apply(K key) {
+                return get(key).getOrElseThrow(() -> new NoSuchElementException(String.valueOf(key)));
+            }
+            @Override
+            public boolean isDefinedAt(K key) {
+                return containsKey(key);
+            }
+        };
     }
 
     @Override
@@ -659,29 +674,6 @@ default Iterator<V> valuesIterator() {
         return iterator().map(Tuple2::_2);
     }
 
-    /**
-     * Turns this map from a partial function into a total function that
-     * returns a value computed by defaultFunction for all keys
-     * absent from the map.
-     *
-     * @param defaultFunction function to evaluate for all keys not present in the map
-     * @return a total function from K to T
-     */
-    default Function1<K, V> withDefault(Function<? super K, ? extends V> defaultFunction) {
-        return k -> get(k).getOrElse(() -> defaultFunction.apply(k));
-    }
-
-    /**
-     * Turns this map from a partial function into a total function that
-     * returns defaultValue for all keys absent from the map.
-     *
-     * @param defaultValue default value to return for all keys not present in the map
-     * @return a total function from K to T
-     */
-    default Function1<K, V> withDefaultValue(V defaultValue) {
-        return k -> get(k).getOrElse(defaultValue);
-    }
-
     @Override
     default <U> Seq<Tuple2<Tuple2<K, V>, U>> zip(Iterable<? extends U> that) {
         return zipWith(that, Tuple::of);
@@ -746,11 +738,6 @@ default <U> Seq<U> zipWithIndex(BiFunction<? super Tuple2<K, V>, ? super Integer
     @Override
     io.vavr.collection.Iterator<? extends Map<K, V>> grouped(int size);
 
-    @Override
-    default boolean isDefinedAt(K key) {
-        return containsKey(key);
-    }
-
     @Override
     default boolean isDistinct() {
         return true;

vavr/src/main/java/io/vavr/collection/Multimap.java

@@ -87,7 +87,7 @@
  * @param <V> Value type
  * @author Ruslan Sennov
  */
-public interface Multimap<K, V> extends Traversable<Tuple2<K, V>>, PartialFunction<K, Traversable<V>>, Serializable {
+public interface Multimap<K, V> extends Traversable<Tuple2<K, V>>, Serializable {
 
     long serialVersionUID = 1L;
 
@@ -154,18 +154,35 @@ static <K, V> Multimap<K, V> narrow(Multimap<? extends K, ? extends V> map) {
 
     // -- non-static API
 
-    @Override
-    default Traversable<V> apply(K key) {
-        return get(key).getOrElseThrow(NoSuchElementException::new);
-    }
-
     /**
      * Converts this {@code Multimap} to a {@code Map}
      *
      * @return {@code Map<K, Traversable<V>>}
      */
     Map<K, Traversable<V>> asMap();
 
+    /**
+     * Turns this {@code Multimap} into a {@link PartialFunction} which is defined at a specific index, if this {@code Multimap}
+     * contains the given key. When applied to a defined key, the partial function will return
+     * the {@link Traversable} of this {@code Multimap} that is associated with the key.
+     *
+     * @return a new {@link PartialFunction}
+     * @throws NoSuchElementException when a non-existing key is applied to the partial function
+     */
+    default PartialFunction<K, Traversable<V>> asPartialFunction() throws IndexOutOfBoundsException {
+        return new PartialFunction<K, Traversable<V>>() {
+            private static final long serialVersionUID = 1L;
+            @Override
+            public Traversable<V> apply(K key) {
+                return get(key).getOrElseThrow(NoSuchElementException::new);
+            }
+            @Override
+            public boolean isDefinedAt(K key) {
+                return containsKey(key);
+            }
+        };
+    }
+
     /**
      * Maps this {@code Multimap} to a new {@code Multimap} with different component type by applying a function to its elements.
      *
@@ -318,11 +335,6 @@ default boolean hasDefiniteSize() {
         return true;
     }
 
-    @Override
-    default boolean isDefinedAt(K key) {
-        return containsKey(key);
-    }
-
     @Override
     default boolean isDistinct() {
         return true;

vavr/src/main/java/io/vavr/collection/Seq.java

@@ -42,6 +42,12 @@
  * <li>{@link #update(int, Object)}</li>
  * </ul>
  *
+ * Conversion:
+ *
+ * <ul>
+ * <li>{@link #asPartialFunction}</li>
+ * </ul>
+ *
  * Filtering:
  *
  * <ul>
@@ -106,7 +112,7 @@
  * @param <T> Component type
  * @author Daniel Dietrich
  */
-public interface Seq<T> extends Traversable<T>, PartialFunction<Integer, T>, Serializable {
+public interface Seq<T> extends Traversable<T>, Serializable {
 
     long serialVersionUID = 1L;
 
@@ -140,19 +146,6 @@ static <T> Seq<T> narrow(Seq<? extends T> seq) {
      * @throws NullPointerException if {@code elements} is null
      */
     Seq<T> appendAll(Iterable<? extends T> elements);
-
-    /**
-     * A {@code Seq} is a partial function which returns the element at the specified index by calling
-     * {@linkplain #get(int)}.
-     *
-     * @param index an index
-     * @return the element at the given index
-     * @throws IndexOutOfBoundsException if this is empty, index &lt; 0 or index &gt;= length()
-     */
-    @Override
-    default T apply(Integer index) {
-        return get(index);
-    }
 
     /**
      * Creates an <strong>immutable</strong> {@link java.util.List} view on top of this {@code Seq},
@@ -205,6 +198,16 @@ default T apply(Integer index) {
     @GwtIncompatible
     Seq<T> asJavaMutable(Consumer<? super java.util.List<T>> action);
 
+    /**
+     * Turns this {@code Seq} into a {@link PartialFunction} which is defined at a specific index, if this {@code Seq}
+     * contains at least index + 1 elements. When applied to a defined index, the partial function will return
+     * the value of this {@code Seq} at the specified index.
+     *
+     * @return a new {@link PartialFunction}
+     * @throws IndexOutOfBoundsException if this is empty, index &lt; 0 or index &gt;= length()
+     */
+    PartialFunction<Integer, T> asPartialFunction() throws IndexOutOfBoundsException;
+
     @Override
     <R> Seq<R> collect(PartialFunction<? super T, ? extends R> partialFunction);
 
@@ -585,16 +588,6 @@ default Option<Integer> lastIndexWhereOption(Predicate<? super T> predicate, int
         return Collections.indexOption(lastIndexWhere(predicate, end));
     }
 
-    /**
-     * Turns this sequence into a plain function returning an Option result.
-     *
-     * @return a function that takes an index i and returns the value of
-     * this sequence in a Some if the index is within bounds, otherwise a None.
-     */
-    default Function1<Integer, Option<T>> lift() {
-        return i -> (i >= 0 && i < length()) ? Option.some(apply(i)) : Option.none();
-    }
-
     /**
      * Returns the index of the last occurrence of the given element before or at a given end index
      * or -1 if this does not contain the given element.
@@ -1275,28 +1268,6 @@ default <U> U foldRight(U zero, BiFunction<? super T, ? super U, ? extends U> f)
     @Override
     <U> Seq<U> zipWithIndex(BiFunction<? super T, ? super Integer, ? extends U> mapper);
 
-    /**
-     * Turns this sequence from a partial function into a total function that
-     * returns defaultValue for all indexes that are out of bounds.
-     *
-     * @param defaultValue default value to return for out of bound indexes
-     * @return a total function from index to T
-     */
-    default Function1<Integer, T> withDefaultValue(T defaultValue) {
-        return i -> (i >= 0 && i < length()) ? apply(i) : defaultValue;
-    }
-
-    /**
-     * Turns this sequence from a partial function into a total function that
-     * returns a value computed by defaultFunction for all indexes that are out of bounds.
-     *
-     * @param defaultFunction function to evaluate for all out of bounds indexes.
-     * @return a total function from index to T
-     */
-    default Function1<Integer, T> withDefault(Function<? super Integer, ? extends T> defaultFunction) {
-        return i -> (i >= 0 && i < length()) ? apply(i) : defaultFunction.apply(i);
-    }
-
     @Override
     default boolean isSequential() {
         return true;

vavr/src/main/java/io/vavr/collection/Set.java

@@ -19,7 +19,6 @@
  */
 package io.vavr.collection;
 
-import io.vavr.Function1;
 import io.vavr.PartialFunction;
 import io.vavr.Tuple3;
 import io.vavr.Tuple2;
@@ -82,7 +81,7 @@
  * @param <T> Component type
  * @author Daniel Dietrich, Ruslan Sennov
  */
-public interface Set<T> extends Traversable<T>, Function1<T, Boolean>, Serializable {
+public interface Set<T> extends Traversable<T>, Serializable {
 
     long serialVersionUID = 1L;
 
@@ -116,19 +115,6 @@ static <T> Set<T> narrow(Set<? extends T> set) {
      */
     Set<T> addAll(Iterable<? extends T> elements);
 
-    /**
-     * Tests if a given {@code element} is contained in this {@code Set}.
-     * <p>
-     * This method is equivalent to {@link #contains(Object)}.
-     *
-     * @param element the element to test for membership.
-     * @return {@code true} if the given {@code element} is contained, {@code false} otherwise.
-     */
-    @Override
-    default Boolean apply(T element) {
-        return contains(element);
-    }
-
     /**
      * Calculates the difference between this set and another set.
      * <p>

vavr/src/test/java/io/vavr/MatchTest.java

@@ -20,6 +20,7 @@
 package io.vavr;
 
 import io.vavr.collection.List;
+import io.vavr.collection.Set;
 import io.vavr.control.Either;
 import io.vavr.control.Option;
 import io.vavr.control.Option.Some;
@@ -339,6 +340,17 @@ public void shouldDecomposeListWithNonEmptyTail() {
     }
     */
 
+    // -- Set
+
+    @Test
+    public void shouldDecomposeSet() {
+        final Set<String> abc = Set("abc");
+        final Set<String> result = Match(abc).of( // Does not compile: the Java inference engine sees abc as a Function1<String, Boolean> before a Set<String> thus expects result to be of type Boolean
+                Case($(), () -> abc)
+        );
+        assertThat(result).isEqualTo(abc);
+    }
+
     // -- Validation
 
     @Test