Rename `iterator.flatten` into `iterator.concat`

2 files changed, 19 insertions, 11 deletions

diff --git a/src/gleam/iterator.gleam b/src/gleam/iterator.gleam
index 8ce7355..db57fea 100644
--- a/src/gleam/iterator.gleam
+++ b/src/gleam/iterator.gleam
@@ -413,11 +413,11 @@ pub fn append(to first: Iterator(a), suffix second: Iterator(a)) -> Iterator(a)
   |> Iterator
 }
 
-fn do_flatten(flattened: fn() -> Action(Iterator(a))) -> Action(a) {
+fn do_concat(flattened: fn() -> Action(Iterator(a))) -> Action(a) {
   case flattened() {
     Stop -> Stop
     Continue(it, next_iterator) ->
-      do_append(it.continuation, fn() { do_flatten(next_iterator) })
+      do_append(it.continuation, fn() { do_concat(next_iterator) })
   }
 }
 
@@ -431,13 +431,21 @@ fn do_flatten(flattened: fn() -> Action(Iterator(a))) -> Action(a) {
 /// ```gleam
 /// > from_list([[1, 2], [3, 4]])
 /// > |> map(from_list)
-/// > |> flatten
+/// > |> from_list
+/// > |> concat
 /// > |> to_list
 /// [1, 2, 3, 4]
 /// ```
 ///
+pub fn concat(iterator: Iterator(Iterator(a))) -> Iterator(a) {
+  fn() { do_concat(iterator.continuation) }
+  |> Iterator
+}
+
+// TODO: Add deprecation attribute and then remove later.
+/// This function is deprecated, see `concat` instead.
 pub fn flatten(iterator: Iterator(Iterator(a))) -> Iterator(a) {
-  fn() { do_flatten(iterator.continuation) }
+  fn() { do_concat(iterator.continuation) }
   |> Iterator
 }
 
@@ -466,7 +474,7 @@ pub fn flat_map(
 ) -> Iterator(b) {
   iterator
   |> map(f)
-  |> flatten
+  |> concat
 }
 
 fn do_filter(
@@ -525,7 +533,7 @@ pub fn filter(
 ///
 pub fn cycle(iterator: Iterator(a)) -> Iterator(a) {
   repeat(iterator)
-  |> flatten
+  |> concat
 }
 
 /// Creates an iterator of ints, starting at a given start int and stepping by
diff --git a/test/gleam/iterator_test.gleam b/test/gleam/iterator_test.gleam
index 85f8722..8b7e01d 100644
--- a/test/gleam/iterator_test.gleam
+++ b/test/gleam/iterator_test.gleam
@@ -156,7 +156,7 @@ pub fn map_test() {
 }
 
 // a |> from_list |> flat_map(f) |> to_list ==
-//   a |> list.map(f) |> list.map(to_list) |> list.flatten
+//   a |> list.map(f) |> list.map(to_list) |> list.concat
 pub fn flat_map_test() {
   let test = fn(subject, f) {
     subject
@@ -178,7 +178,7 @@ pub fn flat_map_test() {
   test([1, 2], f)
 }
 
-// a |> from_list |> append(from_list(b)) |> to_list == list.flatten([a, b])
+// a |> from_list |> append(from_list(b)) |> to_list == list.concat([a, b])
 pub fn append_test() {
   let test = fn(left, right) {
     left
@@ -193,13 +193,13 @@ pub fn append_test() {
   test([1, 2], [3, 4])
 }
 
-// a |> list.map(from_list) |> flatten |> to_list == list.flatten(a)
-pub fn flatten_test() {
+// a |> list.map(from_list) |> concat |> to_list == list.concat(a)
+pub fn concat_test() {
   let test = fn(lists) {
     lists
     |> list.map(iterator.from_list)
     |> iterator.from_list
-    |> iterator.flatten
+    |> iterator.concat
     |> iterator.to_list
     |> should.equal(list.concat(lists))
   }