Fix infinite recursion loop in `list.window` when `by` is 0

The function would enter an endless loop if 0 was passed as second argument, for e.g
`list.window([1, 2], 0) // endless loop!`

2 files changed, 8 insertions, 2 deletions

diff --git a/src/gleam/list.gleam b/src/gleam/list.gleam
index e782b45..83870b4 100644
--- a/src/gleam/list.gleam
+++ b/src/gleam/list.gleam
@@ -1913,8 +1913,10 @@ fn do_window(acc: List(List(a)), l: List(a), n: Int) -> List(List(a)) {
 /// ```
 ///
 pub fn window(l: List(a), by n: Int) -> List(List(a)) {
-  do_window([], l, n)
-  |> reverse
+  case n <= 0 {
+    True -> []
+    False -> do_window([], l, n) |> reverse
+  }
 }
 
 /// Returns a list of tuples containing two contiguous elements.
diff --git a/test/gleam/list_test.gleam b/test/gleam/list_test.gleam
index 190a49b..d20f7a0 100644
--- a/test/gleam/list_test.gleam
+++ b/test/gleam/list_test.gleam
@@ -1074,6 +1074,10 @@ pub fn window_test() {
   |> list.window(3)
   |> should.equal([[1, 2, 3], [2, 3, 4], [3, 4, 5]])
 
+  [1, 2, 3]
+  |> list.window(0)
+  |> should.equal([])
+
   // TCO test
   list.range(0, recursion_test_cycles)
   |> list.window(2)