Add tasks for all the new languages

Task/Doubly-linked-list-Traversal/Axe/doubly-linked-list-traversal.axe

@@ -0,0 +1,20 @@
+LINK(L₁,1)→A
+LINK(L₁+10,2)→B
+LINK(L₁+50,3)→C
+
+INSERT(A,B)
+INSERT(A,C)
+
+A→I
+While I≠0
+ Disp VALUE(I)▶Dec,i
+ NEXT(I)→I
+End
+
+Disp "-----",i
+
+B→I
+While I≠0
+ Disp VALUE(I)▶Dec,i
+ PREV(I)→I
+End

Task/Doubly-linked-list-Traversal/Nim/doubly-linked-list-traversal.nim

@@ -0,0 +1,80 @@
+type
+  List[T] = object
+    head, tail: Node[T]
+
+  Node[T] = ref TNode[T]
+
+  TNode[T] = object
+    next, prev: Node[T]
+    data: T
+
+proc initList[T](): List[T] = discard
+
+proc newNode[T](data: T): Node[T] =
+  new(result)
+  result.data = data
+
+proc prepend[T](l: var List[T], n: Node[T]) =
+  n.next = l.head
+  if l.head != nil: l.head.prev = n
+  l.head = n
+  if l.tail == nil: l.tail = n
+
+proc append[T](l: var List[T], n: Node[T]) =
+  n.next = nil
+  n.prev = l.tail
+  if l.tail != nil:
+    l.tail.next = n
+  l.tail = n
+  if l.head == nil:
+    l.head = n
+
+proc insertAfter[T](l: var List[T], r, n: Node[T]) =
+  n.prev = r
+  n.next = r.next
+  n.next.prev = n
+  r.next = n
+  if r == l.tail: l.tail = n
+
+proc remove[T](l: var List[T], n: Node[T]) =
+  if n == l.tail: l.tail = n.prev
+  if n == l.head: l.head = n.next
+  if n.next != nil: n.next.prev = n.prev
+  if n.prev != nil: n.prev.next = n.next
+
+proc `$`[T](l: var List[T]): string =
+  result = ""
+  var n = l.head
+  while n != nil:
+    if result.len > 0: result.add(" -> ")
+    result.add($n.data)
+    n = n.next
+
+iterator traverseForward[T](l: List[T]): T =
+  var n = l.head
+  while n != nil:
+    yield n.data
+    n = n.next
+
+iterator traverseBackward[T](l: List[T]): T =
+  var n = l.tail
+  while n != nil:
+    yield n.data
+    n = n.prev
+
+var l = initList[int]()
+var n = newNode(12)
+var m = newNode(13)
+var i = newNode(14)
+var j = newNode(15)
+l.append(n)
+l.prepend(m)
+l.insertAfter(m, i)
+l.prepend(j)
+l.remove(m)
+
+for i in l.traverseForward():
+  echo "> ", i
+
+for i in l.traverseBackward():
+  echo "< ", i

Task/Doubly-linked-list-Traversal/Oforth/doubly-linked-list-traversal.oforth

@@ -0,0 +1,20 @@
+DList method: forEachNext
+   dup ifNull: [ drop @head ifNull: [ false ] else: [ @head @head true] return ]
+   next dup ifNull: [ drop false ] else: [ dup true ] ;
+
+DList method: forEachPrev
+   dup ifNull: [ drop @tail ifNull: [ false ] else: [ @tail @tail true] return ]
+   prev dup ifNull: [ drop false ] else: [ dup true ] ;
+
+: test
+| dl n |
+   DList new ->dl
+   dl insertFront("A")
+   dl insertBack("B")
+   dl head insertAfter(DNode new("C", null , null))
+
+   "Traversal (beginning to end) : " println
+   dl forEach: n [ n . ]
+
+   "\nTraversal (end to beginning) : " println
+   dl revEach: n [ n . ] ;