(del! coll key)
  coll: a deque or a tab
  key: any type
  returns #n

Deletes an item from a collection, without returning it.

The simplest way to call this function is (del! coll key). If the index key is not present, it's an error.

The ? special syntax can be used to permit missing items: (del! coll (? key)). In that case, the function will succeed even if the index key is not present.

When coll is a deque, slicing syntax is supported: (del! coll 2 :). This will delete all elements with an index of 2 or more. del! is usually more efficient than remove! when deleting a slice, because it doesn't need to perform any allocation.