v^v

The title of this article is incorrect because of technical limitations. The correct title is v^v.

v^v is an esolang created by User:Username1234.

Brief intro

There are only two useful characters in this language: v and ^. If you want to write annotation, you need to write it behind a )).

Operators

^ separates the operators so all you need to care about is the number of v in every operator.

Caption text

Number	Meaning
1	Push v into the stack
2	Pop the top of the stack
3	Print the top of the stack
4	Change the ASCII of the top of the stack by one
5	Change the ASCII of the top of the stack by negative one
6	Change the top to (the ASCII of the top element)the ASCII of the top element mod 128
7	End of the programme

Example

Print out "CCF"

v^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvv^vv^v^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvv^vv^v^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvvv^vvv^vv^vvvvvvv

Implementation

The following program in Common Lisp offers an interpreter for the language:

(defun interpret-v^v (code &aux (code-length (length code)) (position 0) (command 0) (stack NIL))
  "Executes the piece of v^v CODE and returns NIL."
  (declare (type string code) (type fixnum code-length position) (type (integer 0 *) command) (type list stack))
  (symbol-macrolet ((finished-p (>= position code-length))
                    (token      (the character (char code position))))
    (flet ((execute-command ()
            (case command
              (1 (push command stack))
              (2 (pop stack))
              (3 (write-char (code-char (first stack))))
              (4 (incf (first stack)))
              (5 (decf (first stack)))
              (6 (setf (first stack) (mod (expt (first stack) (first stack)) 128)))
              (7 (setf position code-length))
              (otherwise (error "Invalid command: ~d." command)))
            (values)))
      (loop until finished-p do
        (case token
          (#\^
            (execute-command)
            (setf command 0)
            (incf position))
          (#\v
            (setf command
              (loop while (and (not finished-p) (char= token #\v))
                    do (incf position)
                    count 1)))
          (#\)
            (incf position)
            (if (and (not finished-p) (char= token #\)))
              (loop until finished-p do (incf position))
              (error "Invalid token starting with ')'.")))
          (otherwise
            (error "Invalid token ~s at position ~d." token position)))
        finally (execute-command)))))

The arduous process of generating a message output program can be alleviated by the following function:

(defun build-message-program (text &key (destination NIL))
  "Creates a v^v program which outputs the TEXT and writes the code to
   the DESTINATION, returning for a non-NIL DESTINATION the NIL value,
   otherwise responding with a fresh string containing the result."
  (declare (type string text) (type (or null (eql T) stream string) destination))
  (the (or null string)
    (if destination
      (loop for character of-type character across text do
          ;; Push the number one (1) unto the stack.
          (format destination "v^")
          ;; Increment the one-valued top stack element until it matches
          ;; the CHARACTER's ASCII code.
          (loop repeat (1- (char-code character)) do
            (format destination "vvvv^"))
          ;; Print the top of the stack as an ASCII character.
          (format destination "vvv^")
          ;; Pop the just printed top of the stack.
          (format destination "vv^")
        ;; Write program end.
        finally (format destination "vvvvvvv"))
      (with-output-to-string (output)
        (declare (type string-stream output))
        (build-message-program text :destination output)))))