deprecate concat

4 files changed, 20 insertions, 17 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c48880a..d734bbe 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,8 @@
 - The `float` modeule gains the `to_precision` function.
 - The `try_fold` function in the `iterator` module is now tail recursive.
 - The performance of many functions in the `string` module has been improved.
+- The `concat` function in the `list` module has been deprecated in favour of
+  `flatten`.
 
 ## v0.40.0 - 2024-08-19
 
diff --git a/src/gleam/dynamic.gleam b/src/gleam/dynamic.gleam
index 5b3bb46..f142034 100644
--- a/src/gleam/dynamic.gleam
+++ b/src/gleam/dynamic.gleam
@@ -1087,7 +1087,7 @@ pub fn decode2(
   fn(value) {
     case t1(value), t2(value) {
       Ok(a), Ok(b) -> Ok(constructor(a, b))
-      a, b -> Error(list.concat([all_errors(a), all_errors(b)]))
+      a, b -> Error(list.flatten([all_errors(a), all_errors(b)]))
     }
   }
 }
@@ -1121,7 +1121,7 @@ pub fn decode3(
     case t1(value), t2(value), t3(value) {
       Ok(a), Ok(b), Ok(c) -> Ok(constructor(a, b, c))
       a, b, c ->
-        Error(list.concat([all_errors(a), all_errors(b), all_errors(c)]))
+        Error(list.flatten([all_errors(a), all_errors(b), all_errors(c)]))
     }
   }
 }
@@ -1169,7 +1169,7 @@ pub fn decode4(
       Ok(a), Ok(b), Ok(c), Ok(d) -> Ok(constructor(a, b, c, d))
       a, b, c, d ->
         Error(
-          list.concat([
+          list.flatten([
             all_errors(a),
             all_errors(b),
             all_errors(c),
@@ -1226,7 +1226,7 @@ pub fn decode5(
       Ok(a), Ok(b), Ok(c), Ok(d), Ok(e) -> Ok(constructor(a, b, c, d, e))
       a, b, c, d, e ->
         Error(
-          list.concat([
+          list.flatten([
             all_errors(a),
             all_errors(b),
             all_errors(c),
@@ -1288,7 +1288,7 @@ pub fn decode6(
         Ok(constructor(a, b, c, d, e, f))
       a, b, c, d, e, f ->
         Error(
-          list.concat([
+          list.flatten([
             all_errors(a),
             all_errors(b),
             all_errors(c),
@@ -1354,7 +1354,7 @@ pub fn decode7(
         Ok(constructor(a, b, c, d, e, f, g))
       a, b, c, d, e, f, g ->
         Error(
-          list.concat([
+          list.flatten([
             all_errors(a),
             all_errors(b),
             all_errors(c),
@@ -1424,7 +1424,7 @@ pub fn decode8(
         Ok(constructor(a, b, c, d, e, f, g, h))
       a, b, c, d, e, f, g, h ->
         Error(
-          list.concat([
+          list.flatten([
             all_errors(a),
             all_errors(b),
             all_errors(c),
@@ -1498,7 +1498,7 @@ pub fn decode9(
         Ok(constructor(a, b, c, d, e, f, g, h, i))
       a, b, c, d, e, f, g, h, i ->
         Error(
-          list.concat([
+          list.flatten([
             all_errors(a),
             all_errors(b),
             all_errors(c),
diff --git a/src/gleam/list.gleam b/src/gleam/list.gleam
index f0248e7..c363cda 100644
--- a/src/gleam/list.gleam
+++ b/src/gleam/list.gleam
@@ -699,6 +699,7 @@ fn do_concat(lists: List(List(a)), acc: List(a)) -> List(a) {
 /// // -> [1, 2, 3]
 /// ```
 ///
+@deprecated("Use `list.flatten` instead.")
 pub fn concat(lists: List(List(a))) -> List(a) {
   do_concat(lists, [])
 }
@@ -730,7 +731,7 @@ pub fn flatten(lists: List(List(a))) -> List(a) {
 ///
 pub fn flat_map(over list: List(a), with fun: fn(a) -> List(b)) -> List(b) {
   map(list, fun)
-  |> concat
+  |> flatten
 }
 
 /// Reduces a list of elements into a single value by calling a given function
@@ -1888,7 +1889,7 @@ pub fn permutations(list: List(a)) -> List(List(a)) {
         |> permutations
         |> map(fn(permutation) { [i, ..permutation] })
       })
-      |> concat
+      |> flatten
   }
 }
 
@@ -2216,7 +2217,7 @@ fn do_combination_pairs(items: List(a)) -> List(List(#(a, a))) {
 ///
 pub fn combination_pairs(items: List(a)) -> List(#(a, a)) {
   do_combination_pairs(items)
-  |> concat
+  |> flatten
 }
 
 /// Make a list alternating the elements from the given lists
@@ -2230,7 +2231,7 @@ pub fn combination_pairs(items: List(a)) -> List(#(a, a)) {
 ///
 pub fn interleave(list: List(List(a))) -> List(a) {
   transpose(list)
-  |> concat
+  |> flatten
 }
 
 /// Transpose rows and columns of the list of lists.
@@ -2262,7 +2263,7 @@ pub fn transpose(list_of_list: List(List(a))) -> List(List(a)) {
       let firsts =
         rows
         |> map(take_first)
-        |> concat
+        |> flatten
       let rest = transpose(map(rows, drop(_, 1)))
       [firsts, ..rest]
     }
diff --git a/test/gleam/iterator_test.gleam b/test/gleam/iterator_test.gleam
index 6ae1d4c..f774a62 100644
--- a/test/gleam/iterator_test.gleam
+++ b/test/gleam/iterator_test.gleam
@@ -207,7 +207,7 @@ pub fn flat_map_test() {
       subject
       |> list.map(f)
       |> list.map(iterator.to_list)
-      |> list.concat,
+      |> list.flatten,
     )
   }
 
@@ -225,7 +225,7 @@ pub fn append_test() {
     |> iterator.from_list
     |> iterator.append(iterator.from_list(right))
     |> iterator.to_list
-    |> should.equal(list.concat([left, right]))
+    |> should.equal(list.flatten([left, right]))
   }
 
   testcase([], [])
@@ -241,7 +241,7 @@ pub fn flatten_test() {
     |> iterator.from_list
     |> iterator.flatten
     |> iterator.to_list
-    |> should.equal(list.concat(lists))
+    |> should.equal(list.flatten(lists))
   }
 
   testcase([[], []])
@@ -256,7 +256,7 @@ pub fn concat_test() {
     |> list.map(iterator.from_list)
     |> iterator.concat
     |> iterator.to_list
-    |> should.equal(list.concat(lists))
+    |> should.equal(list.flatten(lists))
   }
 
   testcase([[], []])