Queues¶

The following queue manipulation routines are available once included with the use_module(library(queues)) command.

Queues are implemented with difference lists.

In this package, a queue is represented as a term Front-Back, where Front is a list and Back is a tail of that list, and is normally a variable. join_queue will only work when the Back is a variable, the other routines will accept any tail. The elements of the queue are the list difference, that is, all the elements starting at Front and stopping at Back. Examples:

[a,b,c,d,e|Z]-Z has elements a,b,c,d,e [a,b,c,d,e]-[d,e] has elements a,b,c Z-Z has no elements [1,2,3]-[1,2,3] has no elements

• list_to_queue/3
• list_jump_queue/4
• list_join_queue/4
• length_queue/3
• jump_queue/4
• join_queue/4
• prolog::queue_to_list/2
• prolog::list_to_queue/2
• prolog::length_queue/2
• prolog::empty_queue/1
• prolog::serve_queue/3
• prolog::head_queue/2
• prolog::list_jump_queue/3
• prolog::jump_queue/3
• prolog::list_join_queue/3
• prolog::join_queue/3
• prolog::make_queue/1