feat: Added take_rev

src/dllist.gleam

@@ -15,25 +15,25 @@ pub type DLList(a) {
 }
 
 pub fn main() {
-  let l = new()
+  // let l = new()
-  let l2 = insert(l, 123) |> echo
+  // let l2 = insert(l, 123) |> echo
-  let l3 = insert(l2, 456) |> echo
+  // let l3 = insert(l2, 456) |> echo
-  let l4 = insert(l3, 789)
+  // let l4 = insert(l3, 789)
-  let l5 = insert(l4, 0)
+  // let l5 = insert(l4, 0)
 
-  get(l5) |> echo
+  // get(l5) |> echo
-  l5 |> echo
+  // l5 |> echo
-  l5 |> to_list |> echo
+  // l5 |> to_list |> echo
-  let l6 = delete(l5)
+  // let l6 = delete(l5)
-  l6 |> echo
+  // l6 |> echo
-  let l7 = delete(l6)
+  // let l7 = delete(l6)
-  l7 |> echo
+  // l7 |> echo
-  let l8 = delete(l7)
+  // let l8 = delete(l7)
-  l8 |> echo
+  // l8 |> echo
-  let l9 = delete(l8)
+  // let l9 = delete(l8)
-  l9 |> echo
+  // l9 |> echo
 
-  from_list([1, 2, 3, 4]) |> echo
+  // from_list([1, 2, 3, 4]) |> echo
 
   let l1 = new() |> insert(1)
   l1 |> echo
@@ -43,6 +43,13 @@ pub fn main() {
   l2 |> echo
   let l2t = take(l2, 5)
   l2t |> echo
+
+  let l3 = insert(l2, 3)
+  l3 |> echo
+  let l3t = take(l3, 7)
+  l3t |> echo
+  let l3t2 = take_rev(l3, 7)
+  l3t2 |> echo
 }
 
 pub fn new() -> DLList(a) {
@@ -210,6 +217,21 @@ fn take_loop(list: DLList(a), n_times: Int, acc: List(a)) -> List(a) {
   }
 }
 
+pub fn take_rev(list: DLList(a), n_times: Int) -> List(a) {
+  take_rev_loop(list, n_times, [])
+}
+
+fn take_rev_loop(list: DLList(a), n_times: Int, acc: List(a)) -> List(a) {
+  use <- bool.guard(when: is_empty(list), return: [])
+  case n_times {
+    0 -> list.reverse(acc)
+    n -> {
+      let assert Ok(item) = get(list)
+      take_rev_loop(move_left(list), n - 1, [item, ..acc])
+    }
+  }
+}
+
 pub fn to_list(list: DLList(a)) -> List(a) {
   case is_empty(list) {
     True -> []