Qdeql
From Esolang
Qdeql is a language that provides a single byte queue as the only form of memory available to programs.
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[edit] Instructions
= NEXT Dequeue a byte and enqueue it again
- DEC Dequeue a byte, subtract one (wrapping around), and enqueue it
\ BEGIN Dequeue a byte and skip to the instruction after the
corresponding END if the byte is zero; otherwise, enqueue the
byte again, followed by two zero bytes
/ END Go back to the corresponding BEGIN
& INPUT Read a byte from stdin and enqueue it (0 for EOF)
* OUTPUT Dequeue a byte and write it to stdout
If the queue is empty, any instruction that would normally use a value from the queue instead uses 0.
[edit] Computational capability
To be able to access arbitrary amounts of data in a Qdeql program would require storing that data in the queue. But accessing any particular byte more than once requires knowing how many bytes are in the queue, and to determine this would require accessing a particular byte more than once. Therefore, it is not possible to access arbitrary amounts of data in a Qdeql program.
This puts Qdeql into a situation similar to SMETANA's, where the amount of memory a program can use is limited by the size of the program.
[edit] See also
- Sceql, a revised version of Qdeql. Considerably more practical and easy to program in than Qdeql.
