Propose Try.toEither(Throwable => L)

src/main/java/io/vavr/control/Try.java

@@ -1132,6 +1132,22 @@ public final Either<Throwable, T> toEither() {
         }
     }
 
+    /**
+     * Converts this {@code Try} to an {@link Either}, converting the Throwable (in the failure case)
+     * to a left value using the passed {@link Function}.
+     *
+     * @param <L> left type of the resulting Either
+     * @param throwableMapper A transformation from throwable to the left type of the new {@code Either}
+     * @return A new {@code Either}
+     */
+    public final <L> Either<L, T> toEither(Function<? super Throwable, ? extends L> throwableMapper) {
+        if (isFailure()) {
+            return Either.left(throwableMapper.apply(getCause()));
+        } else {
+            return Either.right(get());
+        }
+    }
+
     /**
      * Converts this {@code Try} to a {@link Validation}.
      *
@@ -1142,8 +1158,8 @@ public final Validation<Throwable, T> toValidation() {
     }
 
     /**
-     * Converts this {@code Try} to a {@link Validation}, converting the Throwable (if present)
-     * to another object using passed {@link Function}.
+     * Converts this {@code Try} to a {@link Validation}, converting the Throwable (in the failure case)
+     * to another object using the passed {@link Function}.
      *
      * <pre>{@code
      * Validation<String, Integer> = Try.of(() -> 1/0).toValidation(Throwable::getMessage));

src/test/java/io/vavr/control/TryTest.java

@@ -969,6 +969,13 @@ public void shouldConvertFailureToEitherLeftSupplier() {
         assertThat(failure().toEither(() -> "test").isLeft()).isTrue();
     }
 
+    @Test
+    public void shouldConvertFailureToEitherLeftMapper() {
+        final Try<Object> failure = Try.failure(new RuntimeException("a certain value"));
+        final Either<String, Object> either = failure.toEither(Throwable::getMessage);
+        assertThat(either).isEqualTo(Either.left("a certain value"));
+    }
+
 
     // -- toValidation