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Paradigm(s) Imperative
Designed by User:PixelatedStarfish
Appeared in 2021
Memory system Deque-based
Computational class Turing Complete
Major implementations Unimplemented
Influenced by Blood32, Something, Heck, Broken Calculator, Wheel
File extension(s) .vssl

Vessel (Virtual machinE Simulating Stack and queuE Language) is a language designed by User:PixelatedStarfish in 2021. As the name suggests, the language is designed to simulate theoretical machines. Vessel is designed with an acceptable degree of practicality in mind. It features several high-level operations to preserve the sanity of programmers.



The following tokens are utilized in this language:

  • Command is a command, such as one that starts an instruction.
  • Value is an integer value between 0 and 255 or any address that points to such an integer.
  • Address is a pointer to a memory location on the grid, deque, or input register.
  • String is a literal string of characters, such as Hello World!

Grammar in EBNF

Program ::= {Instruction}
Instruction ::= Command, {Param, Space}, Newline
Param ::= Value | Address | String | Label | Identifier  
Address ::= ValAddress | InputString 
String ::= {Char}
Label ::= ('L' | 'LBL' | 'LABEL'), Space, Identifier
Identifier ::= {Letter | Digit}
ValAddress ::= Cell | DeqVal | InputInt
Cell ::= 'C'
DeqVal ::= 'T' | 'B'
InputInt ::= 'I'
InputString ::= 'S'
Command::= {Letter}, Space
Value ::= {Digit} | Address
Space ::= ' '
Newline ::= '\n'
Digit ::= '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9'
Letter ::= 
'A' | 'B' | 'C' | 'D' | 'E' | 'F' | 'G' | 'H' | 'I' | 'J' | 'K' | 'L' | 
'M' | 'N' | 'O' | 'P' | 'Q' | 'R' | 'S' | 'T' | 'U' | 'V' | 'W' | 'X' | 'Y' | 'Z'
Char ::= a printable ASCII character.


Table of commands
Command Arguments Description
BEGIN / START None An optional label to indicate the start of execution.
GRID Value; Value A header operation to initialize an x by y grid.
MOVX / MX Value Move the grid pointer to the right by the specified number of cells.
MOVY / MY Value Move the grid pointer up by the specified number of cells.
JUMP / J Value; Value Jump to cell specified at (x,y).
QUE / ENQ Value Enqueue Value at bottom of deque.
DEQ / POP None Dequeue or pop Value at top of deque.
PUSH Value Push Value onto top of deque.
DUP None Duplicate Value at top and push.
SHFL / SHUFFLE None Shuffles the deque.
RCW None Rotate Clockwise. Value on top of deque shifts to bottom and values shift up.
RCCW / RACW None Rotate opposite of clockwise. Values shift down; Value at bottom goes to top.
PCHR Value Print value as ASCII character.
PVAL Value Print value.
PSLT String Print String literal.
PGRID None Print grid.
PDEQ None Print deque.
STR / STORE Address; Value Store value at address.
ADD Address; Value; Value Adds two values and stores at address.
SUB Address; Value; Value Subtracts argument 2 from argument 1 and stores at address.
MUL / PROD Address; Value; Value Multiplies two values and stores at address.
DIV / QUO Address; Value; Value Divides argument 1 by argument 2, takes the floor of the quotient, and stores at address.
MOD Address; Value; Value Performs the Modulo operation with two values and stores at address.
RFL Address; Value; Value Takes the floor of the radical (root) operation and stores at address. Argument 1 is the radicand and argument 2 is the index (the latter being the root, or degree thereof).
POW / EXP Address; Value; Value Raise argument 1 to the power of argument 2 and store at address.
LBL / LABEL / L Identifier A label.
G / GOTO Label Go to the specified label.
CBZ Label; Value Go to label if value is zero. (Compare and branch if zero.)
CBNZ Label; Value Go to label if value is not zero. (Compare and branch if not zero.)
CBV Label; Value; Value Go to label if argument 1 is equal to argument 2.
RET / RETURN / GOBL / GOBLINS None Return to the last go to statement executed (not a branch) and start execution at the next line. This is a subroutine operation. See Goblins Operation.
WAIT / SLEEP Value Pause execution for the number of milliseconds indicated.
INPUT / INP String Print String (or "Input Requested" if not specified). Then take input and store at the input register.
NOTE / CMT / COMMENT None A comment.
HALT / H / HLT / END None End Program. A halt command.
THROW / EXCEPT / EXCEPTION String Throw exception and print an error message ("Error" if not specified). Terminate execution.


Cells and the Grid

The Grid is a two dimensional array of cells. Cells can store values from 0 - 15 in hex:

0 1 2 3 4 5 6 7 8 9 A B C D E F

The value on each cell can be modified with arithmetic commands, but they cannot have a value lees than 0 or more than F. Cell values wrap around; so (0 - 1) = F and (F + 1) = 0.

Cells on the gird are accessible via a pointer that moves in orthogonal directions.

Values on the Deque

The deque is a data structure that allows for operations on a queue and stack. Deque is short for Double Ended Queue It is essentially a queue that has the ability to change the direction of data processing at any time. Enqueues (or pushes) and dequeues (or pops) can be performed on either end of the deque. The deque can also rotate, which moves a value on one end to the other.

A value on the deque is an integer in the range from 0 to 255. Various commands can manipulate deque values and their respective positions on the deque. A value on the deque cannot be less than 0 or more than 255. Values also wrap, so (255 + 1) = 0 and (0 - 1) = 255.

Accessing Memory Addresses

The following operations can be used in a command argument to access memory addresses:

  • C gets the value of the cell currently pointed to.
  • T gets the value at the top of the deque.
  • B gets the value at the top of the deque.
  • I gets input at the input register and parses it as an integer.
  • S gets input at the input register as a string

Program Examples

Hello World

PSLT Hello World!

Truth Machine

L 1
G 1
L 0

Proof of Turing Completeness

Bf is Turing complete. By translating each bf command to Vessel, it can be shown that Vessel is also Turing complete. In this proof bf cells are substituted with values on the deque. (Note that ' :: ' is a stand-in for a newline.)

Conversion Table
Vessel bf Desc
RCW > increment
RACW < decrement
ADD T 1 + add 1 to cell
SUB T 1 - take 1 from cell
PCHR T . Output ASCII value at deque value
INP , Take input at cell
CBZ x [ Jump past ' ] ' (to label x)
CBZ x :: G y :: L x ] goto ' [ ' (label y) if cell is greater than 0

Possible Rework

In general, a stack is easier to implement and program with than deque. So this could be an alteration to the language. An unbounded grid is also possible, but difficult to implement.