ABCR

ABCR is a queue-based programming language created by Steven Hewitt. It uses three FIFO queues known as A, B, and C that store unbounded integer values, as well as a single register R that stores the result of the last operation. Most of the commands have a different symbol for each of the three queues, and each queue serves a slightly different function.

Queue defaults
When an empty queue is peeked or popped, its behavior will differ based on which queue it is:


 * A defaults to  for both popping and peeking.
 * B defaults to  for both popping and peeking.
 * C defaults to grabbing the character code of the next input character (the rest of which, of course, are queued if more than one input character is given) if popped, or to the current register value if peeked.

Popping from an empty C-queue is the only way to input characters.