Fixes #403. Add fj.data.Option.sequence*, fj.data.Option.traverse.*; add sequenceEither, traverseEither as aliases for sequenceEitherRight, sequenceEitherLeft.

drewctaylorgtri · drewctaylorgtri · commit fc85ee1ede0d · 2020-07-24T16:28:34.000-04:00
diff --git a/core/src/main/java/fj/data/Option.java b/core/src/main/java/fj/data/Option.java
@@ -392,6 +392,18 @@ public final <B> Option<B> sequence(final Option<B> o) {
     return bind(c);
   }
 
+  /**
+   * Sequence the given option and collect the output on the right side of an either.
+   *
+   * @param option the given option
+   * @param <B>    the type of the right value
+   * @param <L>    the type of the left value
+   * @return the either
+   */
+  public static final <L, B> Either<L, Option<B>> sequenceEither(final Option<Either<L, B>> option) {
+    return option.traverseEitherRight(identity());
+  }
+
   /**
    * Sequence the given option and collect the output on the left side of an either.
    *
@@ -529,6 +541,18 @@ public static final <E, B> Validation<E, Option<B>> sequenceValidation(final Opt
     return option.traverseValidation(identity());
   }
 
+  /**
+   * Traverse this option with the given function and collect the output on the right side of an either.
+   *
+   * @param f   the given function
+   * @param <L> the type of the left value
+   * @param <B> the type of the right value
+   * @return the either
+   */
+  public final <L, B> Either<L, Option<B>> traverseEither(final F<A, Either<L, B>> f) {
+    return traverseEitherRight(f);
+  }
+
   /**
    * Traverse this option with the given function and collect the output on the left side of an either.
    *
diff --git a/core/src/test/java/fj/data/OptionTest.java b/core/src/test/java/fj/data/OptionTest.java
@@ -13,6 +13,19 @@
 import static fj.data.List.*;
 import static fj.data.Option.iif;
 import static fj.data.Option.sequence;
+import static fj.data.Option.sequenceEither;
+import static fj.data.Option.sequenceEitherLeft;
+import static fj.data.Option.sequenceEitherRight;
+import static fj.data.Option.sequenceF;
+import static fj.data.Option.sequenceIO;
+import static fj.data.Option.sequenceList;
+import static fj.data.Option.sequenceOption;
+import static fj.data.Option.sequenceP1;
+import static fj.data.Option.sequenceSeq;
+import static fj.data.Option.sequenceSet;
+import static fj.data.Option.sequenceStream;
+import static fj.data.Option.sequenceTrampoline;
+import static fj.data.Option.sequenceValidation;
 import static fj.data.Option.*;
 import static fj.data.Validation.fail;
 import static fj.data.Validation.*;
@@ -226,6 +239,12 @@ public void testBindProduct8() {
         });
   }
 
+  @Test
+  public void testSequenceEither() {
+    assertEquals(right(none()), sequenceEither(none()));
+    assertEquals(right(some("zero")), sequenceEither(some(right("zero"))));
+    assertEquals(left("zero"), sequenceEither(some(left("zero"))));
+  }
 
   @Test
   public void testSequenceEitherLeft() {
@@ -311,6 +330,14 @@ public void testSequenceValidation() {
     assertEquals(Validation.success(some(0)), sequenceValidation(some(Validation.success(0))));
   }
 
+  @Test
+  public void testTraverseEither() {
+    assertEquals(right(none()), none().traverseEither(constant(right(0))));
+    assertEquals(right(some(0)), some("zero").traverseEither(constant(right(0))));
+    assertEquals(right(none()), none().traverseEither(constant(left(0))));
+    assertEquals(left(0), some("zero").traverseEither(constant(left(0))));
+  }
+
   @Test
   public void testTraverseEitherLeft() {
     assertEquals(left(none()), none().traverseEitherLeft(constant(left(0))));
