From 932d5a074e6f5ece1e8f4df601022bba1ee9f84d Mon Sep 17 00:00:00 2001
From: Alexander Bandukwala <7h3kk1d@gmail.com>
Date: Thu, 9 Jun 2022 17:57:29 -0500
Subject: [PATCH] Fix Absent::foldLeft bug

Co-authored-by: Skyler Lutz <skylerlutz@me.com>
---
 .../jnape/palatable/lambda/semigroup/builtin/Absent.java   | 2 +-
 .../palatable/lambda/semigroup/builtin/AbsentTest.java     | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/main/java/com/jnape/palatable/lambda/semigroup/builtin/Absent.java b/src/main/java/com/jnape/palatable/lambda/semigroup/builtin/Absent.java
index 68162ad7..222a5e7d 100644
--- a/src/main/java/com/jnape/palatable/lambda/semigroup/builtin/Absent.java
+++ b/src/main/java/com/jnape/palatable/lambda/semigroup/builtin/Absent.java
@@ -72,7 +72,7 @@ public Maybe<A> checkedApply(Maybe<A> maybeX, Maybe<A> maybeY) {
             @Override
             public Maybe<A> foldLeft(Maybe<A> acc, Iterable<Maybe<A>> maybes) {
                 return trampoline(
-                        into((res, it) -> res.equals(nothing())
+                        into((res, it) -> res.equals(nothing()) || !it.hasNext()
                                 ? terminate(res)
                                 : recurse(tuple(liftA2(aSemigroup, res, it.next()), it))),
                         tuple(acc, maybes.iterator()));
diff --git a/src/test/java/com/jnape/palatable/lambda/semigroup/builtin/AbsentTest.java b/src/test/java/com/jnape/palatable/lambda/semigroup/builtin/AbsentTest.java
index 5ab7b53f..9d3dc452 100644
--- a/src/test/java/com/jnape/palatable/lambda/semigroup/builtin/AbsentTest.java
+++ b/src/test/java/com/jnape/palatable/lambda/semigroup/builtin/AbsentTest.java
@@ -71,6 +71,13 @@ public void foldLeftShortCircuit() {
         assertEquals(nothing(), result);
     }
 
+    @Test
+    public void foldLeftWorksForJusts() {
+        Maybe<Unit> result = Absent.<Unit>absent(Constantly::constantly)
+                .foldLeft(just(UNIT), Arrays.asList(just(UNIT), just(UNIT)));
+        assertEquals(just(UNIT), result);
+    }
+
     @Test(timeout = 200)
     public void checkedApplyFoldRightShortCircuit() {
         Maybe<Unit> result = Absent.<Unit>absent().checkedApply(Constantly::constantly)