Simplified PartialFunction towards removing Value.get(), see #2557 (#2669)

Author: danieldietrich

src/main/java/io/vavr/PartialFunction.java

@@ -20,8 +20,6 @@
 
 import io.vavr.control.Option;
 
-import java.util.function.Function;
-
 /**
  * Represents a partial function T -> R that is not necessarily defined for all input values of type T.
  * The caller is responsible for calling the method isDefinedAt() before this function is applied to the value.
@@ -43,62 +41,6 @@ public interface PartialFunction<T, R> extends Function1<T, R> {
      */
     long serialVersionUID = 1L;
 
-    /**
-     * Unlifts a {@code totalFunction} that returns an {@code Option} result into a partial function.
-     * The total function should be side effect free because it might be invoked twice: when checking if the
-     * unlifted partial function is defined at a value and when applying the partial function to a value.
-     *
-     * @param totalFunction the function returning an {@code Option} result.
-     * @param <T> type of the function input, called <em>domain</em> of the function
-     * @param <R> type of the function output, called <em>codomain</em> of the function
-     * @return a partial function that is not necessarily defined for all input values of type T.
-     */
-    static <T, R> PartialFunction<T, R> unlift(Function<? super T, ? extends Option<? extends R>> totalFunction) {
-        return new PartialFunction<T, R>() {
-
-            private static final long serialVersionUID = 1L;
-
-            @Override
-            public R apply(T t) {
-                return totalFunction.apply(t).get();
-            }
-
-            @Override
-            public boolean isDefinedAt(T value) {
-                return totalFunction.apply(value).isDefined();
-            }
-
-        };
-    }
-
-    /**
-     * Factory method for creating a partial function that maps a given {@code Value} to its underlying value.
-     * The partial function is defined for an input {@code Value} if and only if the input {@code Value} is not
-     * empty. If the input {@code Value} is not empty, the partial function will return the underlying value of
-     * the input {@code Value}.
-     *
-     * @param <T> type of the underlying value of the input {@code Value}.
-     * @param <V> type of the function input, called <em>domain</em> of the function
-     * @return a partial function that maps a {@code Value} to its underlying value.
-     */
-    static <T, V extends Value<T>> PartialFunction<V, T> getIfDefined() {
-        return new PartialFunction<V, T>() {
-
-            private static final long serialVersionUID = 1L;
-
-            @Override
-            public T apply(V v) {
-                return v.get();
-            }
-
-            @Override
-            public boolean isDefinedAt(V v) {
-                return !v.isEmpty();
-            }
-
-        };
-    }
-
     /**
      * Applies this function to the given argument and returns the result.
      *

src/test/java/io/vavr/PartialFunctionTest.java

@@ -19,13 +19,9 @@
 package io.vavr;
 
 import io.vavr.collection.HashMap;
-import io.vavr.collection.List;
-import io.vavr.control.Either;
 import io.vavr.control.Option;
 import org.junit.Test;
 
-import java.util.function.Predicate;
-
 import static org.assertj.core.api.Assertions.assertThat;
 
 public class PartialFunctionTest {
@@ -42,42 +38,4 @@ public void shouldReturnNone() {
         assertThat(oneToOne).isEqualTo(Option.none());
     }
 
-    @Test
-    public void shouldUnliftTotalFunctionReturningAnOption() {
-        final Predicate<Number> isEven = n -> n.intValue() % 2 == 0;
-        final Function1<Number, Option<String>> totalFunction = n -> isEven.test(n) ? Option.some("even") : Option.none();
-
-        final PartialFunction<Integer, CharSequence> partialFunction = PartialFunction.unlift(totalFunction);
-
-        assertThat(partialFunction.isDefinedAt(1)).isFalse();
-        assertThat(partialFunction.isDefinedAt(2)).isTrue();
-        assertThat(partialFunction.apply(2)).isEqualTo("even");
-    }
-
-    @Test
-    public void shouldNotBeDefinedAtLeft() {
-        final Either<RuntimeException, Object> left = Either.left(new RuntimeException());
-
-        assertThat(PartialFunction.getIfDefined().isDefinedAt(left)).isFalse();
-    }
-
-    @Test
-    public void shouldBeDefinedAtRight() {
-        Either<Object, Number> right = Either.right(42);
-
-        PartialFunction<Either<Object, Number>, Number> ifDefined = PartialFunction.getIfDefined();
-
-        assertThat(ifDefined.isDefinedAt(right)).isTrue();
-        assertThat(ifDefined.apply(right)).isEqualTo(42);
-    }
-
-    @Test
-    public void shouldCollectSomeValuesAndIgnoreNone() {
-        final List<Integer> evenNumbers = List.range(0, 10)
-          .map(n -> n % 2 == 0 ? Option.some(n) : Option.<Integer>none())
-          .collect(PartialFunction.getIfDefined());
-
-        assertThat(evenNumbers).containsExactly(0, 2, 4, 6, 8);
-    }
-
 }