datatypes: change optional to result (#16546)

vlib/datatypes/bstree.v

@@ -256,13 +256,13 @@ fn (bst &BSTree[T]) get_node(node &BSTreeNode[T], value T) &BSTreeNode[T] {
 //```v
 // left_value, exist := bst.to_left(10)
 //```
-pub fn (bst &BSTree[T]) to_left(value T) ?T {
+pub fn (bst &BSTree[T]) to_left(value T) !T {
 	if bst.is_empty() {
-		return none
+		return error('BSTree is empty')
 	}
 	node := bst.get_node(bst.root, value)
 	if !node.is_init {
-		return none
+		return error('BSTree is not initialized')
 	}
 	left_node := node.left
 	return left_node.value
@@ -275,13 +275,13 @@ pub fn (bst &BSTree[T]) to_left(value T) ?T {
 //```v
 // left_value, exist := bst.to_right(10)
 //```
-pub fn (bst &BSTree[T]) to_right(value T) ?T {
+pub fn (bst &BSTree[T]) to_right(value T) !T {
 	if bst.is_empty() {
-		return none
+		return error('BSTree is empty')
 	}
 	node := bst.get_node(bst.root, value)
 	if !node.is_init {
-		return none
+		return error('BSTree is not initialized')
 	}
 	right_node := node.right
 	return right_node.value
@@ -289,26 +289,26 @@ pub fn (bst &BSTree[T]) to_right(value T) ?T {
 
 // max return the max element inside the BST.
 // Time complexity O(N) if the BST is not balanced
-pub fn (bst &BSTree[T]) max() ?T {
+pub fn (bst &BSTree[T]) max() !T {
 	if bst.is_empty() {
-		return none
+		return error('BSTree is empty')
 	}
 	max := bst.get_max_from_right(bst.root)
 	if !max.is_init {
-		return none
+		return error('BSTree is not initialized')
 	}
 	return max.value
 }
 
 // min return the minimum element in the BST.
 // Time complexity O(N) if the BST is not balanced.
-pub fn (bst &BSTree[T]) min() ?T {
+pub fn (bst &BSTree[T]) min() !T {
 	if bst.is_empty() {
-		return none
+		return error('BSTree is empty')
 	}
 	min := bst.get_min_from_left(bst.root)
 	if !min.is_init {
-		return none
+		return error('BSTree is not initialized')
 	}
 	return min.value
 }

vlib/datatypes/doubly_linked_list.v

@@ -30,7 +30,7 @@ pub fn (list DoublyLinkedList[T]) len() int {
 }
 
 // first returns the first element of the linked list
-pub fn (list DoublyLinkedList[T]) first() ?T {
+pub fn (list DoublyLinkedList[T]) first() !T {
 	if list.is_empty() {
 		return error('Linked list is empty')
 	}
@@ -38,7 +38,7 @@ pub fn (list DoublyLinkedList[T]) first() ?T {
 }
 
 // last returns the last element of the linked list
-pub fn (list DoublyLinkedList[T]) last() ?T {
+pub fn (list DoublyLinkedList[T]) last() !T {
 	if list.is_empty() {
 		return error('Linked list is empty')
 	}
@@ -80,7 +80,7 @@ pub fn (mut list DoublyLinkedList[T]) push_front(item T) {
 }
 
 // pop_back removes the last element of the linked list
-pub fn (mut list DoublyLinkedList[T]) pop_back() ?T {
+pub fn (mut list DoublyLinkedList[T]) pop_back() !T {
 	if list.is_empty() {
 		return error('Linked list is empty')
 	}
@@ -101,7 +101,7 @@ pub fn (mut list DoublyLinkedList[T]) pop_back() ?T {
 }
 
 // pop_front removes the last element of the linked list
-pub fn (mut list DoublyLinkedList[T]) pop_front() ?T {
+pub fn (mut list DoublyLinkedList[T]) pop_front() !T {
 	if list.is_empty() {
 		return error('Linked list is empty')
 	}
@@ -122,7 +122,7 @@ pub fn (mut list DoublyLinkedList[T]) pop_front() ?T {
 }
 
 // insert adds an element to the linked list at the given index
-pub fn (mut list DoublyLinkedList[T]) insert(idx int, item T) ? {
+pub fn (mut list DoublyLinkedList[T]) insert(idx int, item T) ! {
 	if idx < 0 || idx > list.len {
 		return error('Index ${idx} out of bounds [0..${list.len}]')
 	} else if idx == 0 {
@@ -212,7 +212,7 @@ fn (list &DoublyLinkedList[T]) node(idx int) &DoublyListNode[T] {
 
 // index searches the linked list for item and returns the forward index
 // or none if not found.
-pub fn (list &DoublyLinkedList[T]) index(item T) ?int {
+pub fn (list &DoublyLinkedList[T]) index(item T) !int {
 	mut hn := list.head
 	mut tn := list.tail
 	for h, t := 0, list.len - 1; h <= t; {
@@ -226,7 +226,7 @@ pub fn (list &DoublyLinkedList[T]) index(item T) ?int {
 		t -= 1
 		tn = tn.prev
 	}
-	return none
+	return error('none')
 }
 
 // delete removes index idx from the linked list and is safe to call

vlib/datatypes/doubly_linked_list_test.v

@@ -7,118 +7,118 @@ fn test_is_empty() {
 	assert list.is_empty() == false
 }
 
-fn test_len() ? {
+fn test_len() {
 	mut list := DoublyLinkedList[int]{}
 	assert list.len() == 0
 	list.push_back(1)
 	assert list.len() == 1
-	list.pop_back()?
+	list.pop_back()!
 	assert list.len() == 0
 }
 
-fn test_first() ? {
+fn test_first() {
 	mut list := DoublyLinkedList[int]{}
 	list.push_back(1)
-	assert list.first()? == 1
+	assert list.first()! == 1
 	list.push_back(2)
-	assert list.first()? == 1
+	assert list.first()! == 1
 	list = DoublyLinkedList[int]{}
 	list.first() or { return }
 	assert false
 }
 
-fn test_last() ? {
+fn test_last() {
 	mut list := DoublyLinkedList[int]{}
 	list.push_back(1)
-	assert list.last()? == 1
+	assert list.last()! == 1
 	list.push_back(2)
-	assert list.last()? == 2
+	assert list.last()! == 2
 	list = DoublyLinkedList[int]{}
 	list.last() or { return }
 	assert false
 }
 
-fn test_push() ? {
+fn test_push() {
 	mut list := DoublyLinkedList[int]{}
 	list.push_back(1)
-	assert list.last()? == 1
+	assert list.last()! == 1
 	list.push_back(2)
-	assert list.last()? == 2
+	assert list.last()! == 2
 	list.push_back(3)
-	assert list.last()? == 3
+	assert list.last()! == 3
 }
 
-fn test_pop() ? {
+fn test_pop() {
 	mut list := DoublyLinkedList[int]{}
 	list.push_back(1)
 	list.push_back(2)
 	list.push_back(3)
-	assert list.pop_back()? == 3
+	assert list.pop_back()! == 3
 	list.push_back(4)
-	assert list.pop_back()? == 4
-	assert list.pop_back()? == 2
+	assert list.pop_back()! == 4
+	assert list.pop_back()! == 2
 	list = DoublyLinkedList[int]{}
 	list.pop_back() or { return }
 	assert false
 }
 
-fn test_pop_front() ? {
+fn test_pop_front() {
 	mut list := DoublyLinkedList[int]{}
 	list.push_back(1)
 	list.push_back(2)
 	list.push_back(3)
-	assert list.pop_front()? == 1
+	assert list.pop_front()! == 1
 	list.push_back(4)
-	assert list.pop_front()? == 2
-	assert list.pop_front()? == 3
+	assert list.pop_front()! == 2
+	assert list.pop_front()! == 3
 	list = DoublyLinkedList[int]{}
 	list.pop_front() or { return }
 	assert false
 }
 
-fn test_insert() ? {
+fn test_insert() {
 	mut list := DoublyLinkedList[int]{}
 	list.push_back(1)
 	list.push_back(2)
 	list.push_back(3)
 	// [1, 2, 3]
-	list.insert(1, 111)?
+	list.insert(1, 111)!
 	// [1, 111, 2, 3]
-	list.insert(3, 222)?
+	list.insert(3, 222)!
 	// [1, 111, 2, 222, 3]
-	assert list.pop_back()? == 3
-	assert list.pop_back()? == 222
-	assert list.pop_front()? == 1
-	assert list.pop_front()? == 111
+	assert list.pop_back()! == 3
+	assert list.pop_back()! == 222
+	assert list.pop_front()! == 1
+	assert list.pop_front()! == 111
 }
 
-fn test_push_front() ? {
+fn test_push_front() {
 	mut list := DoublyLinkedList[int]{}
 	list.push_back(1)
 	list.push_back(2)
 	list.push_back(3)
 	list.push_front(111)
-	assert list.first()? == 111
+	assert list.first()! == 111
 }
 
-fn test_delete() ? {
+fn test_delete() {
 	mut list := DoublyLinkedList[int]{}
 	list.push_back(0)
 	list.push_back(1)
 	list.push_back(2)
 	list.delete(1)
-	assert list.first()? == 0
-	assert list.last()? == 2
+	assert list.first()! == 0
+	assert list.last()! == 2
 	assert list.len() == 2
 	list.delete(1)
-	assert list.first()? == 0
-	assert list.last()? == 0
+	assert list.first()! == 0
+	assert list.last()! == 0
 	assert list.len() == 1
 	list.delete(0)
 	assert list.len() == 0
 }
 
-fn test_iter() ? {
+fn test_iter() {
 	mut list := DoublyLinkedList[int]{}
 	for i := 0; i < 10; i++ {
 		list.push_back(i * 10)
@@ -140,18 +140,18 @@ fn test_iter() ? {
 	assert count == 10
 }
 
-fn test_index() ? {
+fn test_index() {
 	mut list := DoublyLinkedList[int]{}
 	for i := 0; i < 10; i++ {
 		list.push_back(i * 10)
 	}
 
 	for i := 0; i < 10; i++ {
-		assert list.index(i * 10)? == i
+		assert list.index(i * 10)! == i
 	}
 }
 
-fn test_str() ? {
+fn test_str() {
 	mut list := DoublyLinkedList[int]{}
 	list.push_back(1)
 	list.push_back(2)
@@ -159,7 +159,7 @@ fn test_str() ? {
 	assert list.str() == '[1, 2, 3]'
 }
 
-fn test_array() ? {
+fn test_array() {
 	mut list := DoublyLinkedList[int]{}
 	list.push_back(1)
 	list.push_back(2)
@@ -167,7 +167,7 @@ fn test_array() ? {
 	assert list.array() == [1, 2, 3]
 }
 
-fn test_string_array() ? {
+fn test_string_array() {
 	mut list := DoublyLinkedList[[]string]{}
 	list.push_back(['a'])
 	list.push_back(['b'])
@@ -175,7 +175,7 @@ fn test_string_array() ? {
 	assert list.array() == [['a'], ['b'], ['c']]
 }
 
-fn test_iteration_with_for() ? {
+fn test_iteration_with_for() {
 	mut list := DoublyLinkedList[int]{}
 	list.push_back(1)
 	list.push_back(2)
@@ -187,7 +187,7 @@ fn test_iteration_with_for() ? {
 	assert res == [1, 2, 3]
 }
 
-fn test_iterator() ? {
+fn test_iterator() {
 	mut list := DoublyLinkedList[int]{}
 	list.push_back(1)
 	list.push_back(2)
@@ -200,7 +200,7 @@ fn test_iterator() ? {
 	assert res == [1, 2, 3]
 }
 
-fn test_back_iterator() ? {
+fn test_back_iterator() {
 	mut list := DoublyLinkedList[int]{}
 	list.push_back(1)
 	list.push_back(2)

vlib/datatypes/heap.v

@@ -21,9 +21,9 @@ pub fn (mut heap MinHeap[T]) insert(item T) {
 }
 
 // pop removes the top-most element from the heap.
-pub fn (mut heap MinHeap[T]) pop() ?T {
+pub fn (mut heap MinHeap[T]) pop() !T {
 	if heap.data.len == 0 {
-		return none
+		return error('Heap is empty')
 	} else if heap.data.len == 1 {
 		return heap.data.pop()
 	}
@@ -46,9 +46,9 @@ pub fn (mut heap MinHeap[T]) pop() ?T {
 }
 
 // peek gets the top-most element from the heap without removing it.
-pub fn (heap MinHeap[T]) peek() ?T {
+pub fn (heap MinHeap[T]) peek() !T {
 	if heap.data.len == 0 {
-		return none
+		return error('Heap is empty')
 	}
 	return heap.data[0]
 }
@@ -60,20 +60,20 @@ pub fn (heap MinHeap[T]) len() int {
 
 // left_child is a helper function that returns the index of the left
 // child given a parent idx, or none if there is no left child.
-fn (heap MinHeap[T]) left_child(idx int) ?int {
+fn (heap MinHeap[T]) left_child(idx int) !int {
 	child := 2 * idx + 1
 	if child >= heap.data.len {
-		return none
+		return error('none')
 	}
 	return child
 }
 
 // right_child is a helper function that returns the index of the right
 // child given a parent idx, or none if there is no right child.
-fn (heap MinHeap[T]) right_child(idx int) ?int {
+fn (heap MinHeap[T]) right_child(idx int) !int {
 	child := 2 * idx + 2
 	if child >= heap.data.len {
-		return none
+		return error('none')
 	}
 	return child
 }

vlib/datatypes/heap_test.v

@@ -1,6 +1,6 @@
 module datatypes
 
-fn test_min_heap() ? {
+fn test_min_heap() {
 	mut heap := MinHeap[int]{}
 	heap.insert(2)
 	heap.insert(0)
@@ -8,11 +8,11 @@ fn test_min_heap() ? {
 	heap.insert(4)
 	heap.insert(1)
 
-	assert heap.pop()? == 0
-	assert heap.pop()? == 1
-	assert heap.pop()? == 2
-	assert heap.pop()? == 4
-	assert heap.pop()? == 8
+	assert heap.pop()! == 0
+	assert heap.pop()! == 1
+	assert heap.pop()! == 2
+	assert heap.pop()! == 4
+	assert heap.pop()! == 8
 	if _ := heap.pop() {
 		panic('expected none')
 	}
@@ -27,7 +27,7 @@ fn (lhs Item) < (rhs Item) bool {
 	return rhs.priority < lhs.priority
 }
 
-fn test_min_heap_custom() ? {
+fn test_min_heap_custom() {
 	mut heap := MinHeap[Item]{}
 	heap.insert(Item{'buz', 10})
 	heap.insert(Item{'qux', 0})
@@ -35,17 +35,17 @@ fn test_min_heap_custom() ? {
 	heap.insert(Item{'foo', 100})
 	heap.insert(Item{'bar', 80})
 
-	assert heap.pop()?.data == 'foo'
-	assert heap.pop()?.data == 'bar'
-	assert heap.pop()?.data == 'baz'
-	assert heap.pop()?.data == 'buz'
-	assert heap.pop()?.data == 'qux'
+	assert heap.pop()!.data == 'foo'
+	assert heap.pop()!.data == 'bar'
+	assert heap.pop()!.data == 'baz'
+	assert heap.pop()!.data == 'buz'
+	assert heap.pop()!.data == 'qux'
 	if _ := heap.pop() {
 		panic('expected none')
 	}
 }
 
-fn test_heap_len() ? {
+fn test_heap_len() {
 	mut heap := MinHeap[int]{}
 	heap.insert(2)
 	assert heap.len() == 1
@@ -56,12 +56,12 @@ fn test_heap_len() ? {
 	heap.insert(1)
 
 	assert heap.len() == 5
-	heap.pop()?
-	heap.pop()?
-	heap.pop()?
+	heap.pop()!
+	heap.pop()!
+	heap.pop()!
 	assert heap.len() == 2
-	heap.pop()?
-	heap.pop()?
+	heap.pop()!
+	heap.pop()!
 	assert heap.len() == 0
 	heap.pop() or {}
 	assert heap.len() == 0

vlib/datatypes/linked_list.v

@@ -27,12 +27,12 @@ pub fn (list LinkedList[T]) len() int {
 }
 
 // first returns the first element of the linked list
-pub fn (list LinkedList[T]) first() ?T {
+pub fn (list LinkedList[T]) first() !T {
 	return if !list.is_empty() { list.head.data } else { error('Linked list is empty') }
 }
 
 // last returns the last element of the linked list
-pub fn (list LinkedList[T]) last() ?T {
+pub fn (list LinkedList[T]) last() !T {
 	if unsafe { list.head == 0 } {
 		return error('Linked list is empty')
 	} else {
@@ -45,7 +45,7 @@ pub fn (list LinkedList[T]) last() ?T {
 }
 
 // index returns the element at the given index of the linked list
-pub fn (list LinkedList[T]) index(idx int) ?T {
+pub fn (list LinkedList[T]) index(idx int) !T {
 	if unsafe { list.head == 0 } {
 		return error('Linked list is empty')
 	} else {
@@ -82,7 +82,7 @@ pub fn (mut list LinkedList[T]) push(item T) {
 }
 
 // pop removes the last element of the linked list
-pub fn (mut list LinkedList[T]) pop() ?T {
+pub fn (mut list LinkedList[T]) pop() !T {
 	if unsafe { list.head == 0 } {
 		return error('Linked list is empty')
 	}
@@ -105,7 +105,7 @@ pub fn (mut list LinkedList[T]) pop() ?T {
 }
 
 // shift removes the first element of the linked list
-pub fn (mut list LinkedList[T]) shift() ?T {
+pub fn (mut list LinkedList[T]) shift() !T {
 	if unsafe { list.head == 0 } {
 		return error('Linked list is empty')
 	} else {
@@ -117,7 +117,7 @@ pub fn (mut list LinkedList[T]) shift() ?T {
 }
 
 // insert adds an element to the linked list at the given index
-pub fn (mut list LinkedList[T]) insert(idx int, item T) ? {
+pub fn (mut list LinkedList[T]) insert(idx int, item T) ! {
 	if idx < 0 || idx > list.len {
 		return error('Index ${idx} out of bounds [0..${list.len}]')
 	} else if list.len == 0 {

vlib/datatypes/linked_list_test.v

@@ -7,87 +7,87 @@ fn test_is_empty() {
 	assert list.is_empty() == false
 }
 
-fn test_len() ? {
+fn test_len() {
 	mut list := LinkedList[int]{}
 	assert list.len() == 0
 	list.push(1)
 	assert list.len() == 1
-	list.pop()?
+	list.pop()!
 	assert list.len() == 0
 }
 
-fn test_first() ? {
+fn test_first() {
 	mut list := LinkedList[int]{}
 	list.push(1)
-	assert list.first()? == 1
+	assert list.first()! == 1
 	list.push(2)
-	assert list.first()? == 1
+	assert list.first()! == 1
 	list = LinkedList[int]{}
 	list.first() or { return }
 	assert false
 }
 
-fn test_last() ? {
+fn test_last() {
 	mut list := LinkedList[int]{}
 	list.push(1)
-	assert list.last()? == 1
+	assert list.last()! == 1
 	list.push(2)
-	assert list.last()? == 2
+	assert list.last()! == 2
 	list = LinkedList[int]{}
 	list.last() or { return }
 	assert false
 }
 
-fn test_index() ? {
+fn test_index() {
 	mut list := LinkedList[int]{}
 	list.push(1)
-	assert list.index(0)? == 1
+	assert list.index(0)! == 1
 	list.push(2)
-	assert list.index(1)? == 2
-	list.pop()?
+	assert list.index(1)! == 2
+	list.pop()!
 	list.index(1) or { return }
 	assert false
 }
 
-fn test_push() ? {
+fn test_push() {
 	mut list := LinkedList[int]{}
 	list.push(1)
-	assert list.last()? == 1
+	assert list.last()! == 1
 	list.push(2)
-	assert list.last()? == 2
+	assert list.last()! == 2
 	list.push(3)
-	assert list.last()? == 3
+	assert list.last()! == 3
 }
 
-fn test_pop() ? {
+fn test_pop() {
 	mut list := LinkedList[int]{}
 	list.push(1)
 	list.push(2)
 	list.push(3)
-	assert list.pop()? == 3
+	assert list.pop()! == 3
 	list.push(4)
-	assert list.pop()? == 4
-	assert list.pop()? == 2
+	assert list.pop()! == 4
+	assert list.pop()! == 2
 	list = LinkedList[int]{}
 	list.pop() or { return }
 	assert false
 }
 
-fn test_shift() ? {
+fn test_shift() {
 	mut list := LinkedList[int]{}
 	list.push(1)
 	list.push(2)
 	list.push(3)
-	assert list.shift()? == 1
+	assert list.shift()! == 1
 	list.push(4)
-	assert list.shift()? == 2
-	assert list.shift()? == 3
+	assert list.shift()! == 2
+	assert list.shift()! == 3
 	list = LinkedList[int]{}
 	list.shift() or { return }
 	assert false
 }
 
-fn test_insert() ? {
+fn test_insert() {
 	mut list := LinkedList[int]{}
 	list.push(1)
 	list.push(2)
@@ -96,16 +96,16 @@ fn test_insert() ? {
 	assert true
 }
 
-fn test_prepend() ? {
+fn test_prepend() {
 	mut list := LinkedList[int]{}
 	list.push(1)
 	list.push(2)
 	list.push(3)
 	list.prepend(111)
-	assert list.first()? == 111
+	assert list.first()! == 111
 }
 
-fn test_str() ? {
+fn test_str() {
 	mut list := LinkedList[int]{}
 	list.push(1)
 	list.push(2)
@@ -113,7 +113,7 @@ fn test_str() ? {
 	assert list.str() == '[1, 2, 3]'
 }
 
-fn test_array() ? {
+fn test_array() {
 	mut list := LinkedList[int]{}
 	list.push(1)
 	list.push(2)
@@ -121,7 +121,7 @@ fn test_array() ? {
 	assert list.array() == [1, 2, 3]
 }
 
-fn test_linked_list_iterating_with_for() ? {
+fn test_linked_list_iterating_with_for() {
 	mut list := LinkedList[int]{}
 	list.push(1)
 	list.push(2)
@@ -133,7 +133,7 @@ fn test_linked_list_iterating_with_for() ? {
 	assert res == [1, 2, 3]
 }
 
-fn test_linked_list_separate_iterators() ? {
+fn test_linked_list_separate_iterators() {
 	mut list := LinkedList[int]{}
 	list.push(1)
 	list.push(2)
@@ -141,10 +141,10 @@ fn test_linked_list_separate_iterators() ? {
 	mut it1 := list.iterator()
 	mut it2 := list.iterator()
 	mut it3 := list.iterator()
-	assert it1.next()? == 1
-	assert it1.next()? == 2
-	assert it1.next()? == 3
-	assert it2.next()? == 1
+	assert it1.next()! == 1
+	assert it1.next()! == 2
+	assert it1.next()! == 3
+	assert it2.next()! == 1
 	if _ := it1.next() {
 		assert false
 	} else {
@@ -155,8 +155,8 @@ fn test_linked_list_separate_iterators() ? {
 	} else {
 		assert true
 	}
-	assert it2.next()? == 2
-	assert it2.next()? == 3
+	assert it2.next()! == 2
+	assert it2.next()! == 3
 	if _ := it2.next() {
 		assert false
 	} else {

vlib/datatypes/queue.v

@@ -16,17 +16,17 @@ pub fn (queue Queue[T]) len() int {
 }
 
 // peek returns the head of the queue (first element added)
-pub fn (queue Queue[T]) peek() ?T {
+pub fn (queue Queue[T]) peek() !T {
 	return queue.elements.first()
 }
 
 // last returns the tail of the queue (last element added)
-pub fn (queue Queue[T]) last() ?T {
+pub fn (queue Queue[T]) last() !T {
 	return queue.elements.last()
 }
 
 // index returns the element at the given index of the queue
-pub fn (queue Queue[T]) index(idx int) ?T {
+pub fn (queue Queue[T]) index(idx int) !T {
 	return queue.elements.index(idx)
 }
 
@@ -36,7 +36,7 @@ pub fn (mut queue Queue[T]) push(item T) {
 }
 
 // pop removes the element at the head of the queue and returns it
-pub fn (mut queue Queue[T]) pop() ?T {
+pub fn (mut queue Queue[T]) pop() !T {
 	return queue.elements.shift()
 }
 

vlib/datatypes/queue_test.v

@@ -7,70 +7,70 @@ fn test_is_empty() {
 	assert queue.is_empty() == false
 }
 
-fn test_len() ? {
+fn test_len() {
 	mut queue := Queue[int]{}
 	assert queue.len() == 0
 	queue.push(1)
 	assert queue.len() == 1
-	queue.pop()?
+	queue.pop()!
 	assert queue.len() == 0
 }
 
-fn test_peek() ? {
+fn test_peek() {
 	mut queue := Queue[int]{}
 	queue.push(1)
-	assert queue.peek()? == 1
+	assert queue.peek()! == 1
 	queue.push(2)
-	assert queue.peek()? == 1
+	assert queue.peek()! == 1
 	queue = Queue[int]{}
 	queue.peek() or { return }
 	assert false
 }
 
-fn test_last() ? {
+fn test_last() {
 	mut queue := Queue[int]{}
 	queue.push(1)
-	assert queue.last()? == 1
+	assert queue.last()! == 1
 	queue.push(2)
-	assert queue.last()? == 2
+	assert queue.last()! == 2
 	queue = Queue[int]{}
 	queue.last() or { return }
 	assert false
 }
 
-fn test_index() ? {
+fn test_index() {
 	mut queue := Queue[int]{}
 	queue.push(1)
-	assert queue.index(0)? == 1
+	assert queue.index(0)! == 1
 	queue.push(2)
-	assert queue.index(1)? == 2
-	queue.pop()?
+	assert queue.index(1)! == 2
+	queue.pop()!
 	queue.index(1) or { return }
 	assert false
 }
 
-fn test_push() ? {
+fn test_push() {
 	mut queue := Queue[int]{}
 	queue.push(1)
 	queue.push(2)
-	assert queue.peek()? == 1
+	assert queue.peek()! == 1
 }
 
-fn test_pop() ? {
+fn test_pop() {
 	mut queue := Queue[int]{}
 	queue.push(1)
 	queue.push(2)
 	queue.push(3)
-	assert queue.pop()? == 1
+	assert queue.pop()! == 1
 	queue.push(4)
-	assert queue.pop()? == 2
-	assert queue.pop()? == 3
+	assert queue.pop()! == 2
+	assert queue.pop()! == 3
 	queue = Queue[int]{}
 	queue.pop() or { return }
 	assert false
 }
 
-fn test_array() ? {
+fn test_array() {
 	mut queue := Queue[int]{}
 	queue.push(1)
 	queue.push(2)

vlib/datatypes/ringbuffer.v

@@ -18,7 +18,7 @@ pub fn new_ringbuffer[T](s int) RingBuffer[T] {
 }
 
 // push - adds an element to the ringbuffer
-pub fn (mut rb RingBuffer[T]) push(element T) ? {
+pub fn (mut rb RingBuffer[T]) push(element T) ! {
 	if rb.is_full() {
 		return error('Buffer overflow')
 	} else {
@@ -28,7 +28,7 @@ pub fn (mut rb RingBuffer[T]) push(element T) ? {
 }
 
 // pop - returns the oldest element of the buffer
-pub fn (mut rb RingBuffer[T]) pop() ?T {
+pub fn (mut rb RingBuffer[T]) pop() !T {
 	mut v := rb.content[rb.reader]
 	if rb.is_empty() {
 		return error('Buffer is empty')
@@ -39,14 +39,14 @@ pub fn (mut rb RingBuffer[T]) pop() ?T {
 }
 
 // push_many - pushes an array to the buffer
-pub fn (mut rb RingBuffer[T]) push_many(elements []T) ? {
+pub fn (mut rb RingBuffer[T]) push_many(elements []T) ! {
 	for v in elements {
 		rb.push(v) or { return err }
 	}
 }
 
 // pop_many - returns a given number(n) of elements of the buffer starting with the oldest one
-pub fn (mut rb RingBuffer[T]) pop_many(n u64) ?[]T {
+pub fn (mut rb RingBuffer[T]) pop_many(n u64) ![]T {
 	mut elements := []T{}
 	for _ in 0 .. n {
 		elements << rb.pop() or { return err }

vlib/datatypes/set.v

@@ -21,7 +21,7 @@ pub fn (mut set Set[T]) remove(element T) {
 }
 
 // pick returns an arbitrary element of set, if set is not empty.
-pub fn (set Set[T]) pick() ?T {
+pub fn (set Set[T]) pick() !T {
 	for k, _ in set.elements {
 		return k
 	}
@@ -29,14 +29,14 @@ pub fn (set Set[T]) pick() ?T {
 }
 
 // rest returns the set consisting of all elements except for the arbitrary element.
-pub fn (mut set Set[T]) rest() ?[]T {
-	element := set.pick()?
+pub fn (mut set Set[T]) rest() ![]T {
+	element := set.pick()!
 	return set.elements.keys().filter(it != element)
 }
 
 // pop returns an arbitrary element and deleting it from set.
-pub fn (mut set Set[T]) pop() ?T {
-	element := set.pick()?
+pub fn (mut set Set[T]) pop() !T {
+	element := set.pick()!
 	set.elements.delete(element)
 	return element
 }

vlib/datatypes/stack.v

@@ -16,7 +16,7 @@ pub fn (stack Stack[T]) len() int {
 }
 
 // peek returns the top of the stack
-pub fn (stack Stack[T]) peek() ?T {
+pub fn (stack Stack[T]) peek() !T {
 	return if !stack.is_empty() { stack.elements.last() } else { error('Stack is empty') }
 }
 
@@ -26,7 +26,7 @@ pub fn (mut stack Stack[T]) push(item T) {
 }
 
 // pop removes the element at the top of the stack and returns it
-pub fn (mut stack Stack[T]) pop() ?T {
+pub fn (mut stack Stack[T]) pop() !T {
 	return if !stack.is_empty() { stack.elements.pop() } else { error('Stack is empty') }
 }
 

vlib/datatypes/stack_test.v

@@ -7,51 +7,51 @@ fn test_is_empty() {
 	assert stack.is_empty() == false
 }
 
-fn test_len() ? {
+fn test_len() {
 	mut stack := dt.Stack[int]{}
 	assert stack.len() == 0
 	stack.push(1)
 	assert stack.len() == 1
-	stack.pop()?
+	stack.pop()!
 	assert stack.len() == 0
 }
 
-fn test_peek() ? {
+fn test_peek() {
 	mut stack := dt.Stack[int]{}
 	stack.push(1)
-	assert stack.peek()? == 1
+	assert stack.peek()! == 1
 	stack.push(2)
-	assert stack.peek()? == 2
+	assert stack.peek()! == 2
 	stack = dt.Stack[int]{}
 	stack.peek() or { return }
 	assert false
 }
 
-fn test_push() ? {
+fn test_push() {
 	mut stack := dt.Stack[int]{}
 	stack.push(1)
-	assert stack.peek()? == 1
+	assert stack.peek()! == 1
 	stack.push(2)
-	assert stack.peek()? == 2
+	assert stack.peek()! == 2
 	stack.push(3)
-	assert stack.peek()? == 3
+	assert stack.peek()! == 3
 }
 
-fn test_pop() ? {
+fn test_pop() {
 	mut stack := dt.Stack[int]{}
 	stack.push(1)
 	stack.push(2)
 	stack.push(3)
-	assert stack.pop()? == 3
+	assert stack.pop()! == 3
 	stack.push(4)
-	assert stack.pop()? == 4
-	assert stack.pop()? == 2
+	assert stack.pop()! == 4
+	assert stack.pop()! == 2
 	stack = dt.Stack[int]{}
 	stack.pop() or { return }
 	assert false
 }
 
-fn test_array() ? {
+fn test_array() {
 	mut stack := dt.Stack[int]{}
 	stack.push(1)
 	stack.push(2)