Runic Enchantments 2D Language Interpreter

Runic script is a 2D interpreted language with multiple simultaneously processed instruction pointers. Each instruction pointer (IP) is spawned at an entry point with a mana ("energy") value, a direction, and an empty stack. Each cycle each IP (in order of creation) executes the instuction under itself and then moves forwards. If the instruction requires a quantity of mana and the IP does not have that much, then the update is treated as a NOP and the IP is not advanced.

At the end of each update the following actiosn are performed (in order):

• Any pointers that exist in the same cell and have the same facing are merged: The older one retains its stack and gains the mana of the newer one, which is then destroyed.

• Any IP that has more than 100 mana burns out the rune it is on (making it act like a ) and half of its mana is lost.

• Any IP with a stack size greater than mana + 10 loses 1 mana.

• Any IP that has 0 or less mana is destroyed.

Commands

Rune	Name	Description
	Empty	NOP - Nothing happens. IP will advance to the next cell.
0-9	Integer Literals	Pushes the single digit value onto the stack
a-f	Integer Literals	Literals for the values 10-15
P	Pi	Pushes the value of Pi onto the stack. Can also use π
+ - * , %	Mathematical operators	Addition, Subtraction, Multiplication, Division, and Modulo (All math operations perform an implicit conversion to a number where possible). These also operate on two Vectors where , is a Dot Product and * is a Cross Product. Division by 0 terminates the IP. For strings, + concatenates as yx and * takes a number (cast to int) y and makes that many copies of x (e.g. "asdf"3* pushes `"asdfasdfasdf" onto the stack)
X C Y	Power of Ten	Multiplies the top value of the stack by 10, 100, and 1000 respectively.
Z	Negate	Multiplies the top value on the stack by -1
p	Power	Pops two values x and y and pushes y^x (y raised to the power x) onto the stack (e.g. >23p$; will print 8)
A	Math	Pops two values, o and x, if o is a character, it maps to the single-argument Math functions, passing x as the argument (grouped by relation): S,C,T,i,o,a: Sin, Cos, Tan, ASin, ACos, ATan. f,c,r: Floor, Ceiling, Round. |: Absolute value. e,q,l,L: Exp, Sqrt, Log, Log10
> < ^ v	Entry	Spawns an IP with the indicated facing with 10 mana at program start. Acts as an empty space otherwise.
$ @	Output	$ prints the top value of the stack to Debug.Log(), @ dumps the entire stack and terminates the IP
i	Input	Reads from input treating objects as whitespace-speparated values (eg. 123.4 qwerty will first read a double value of 123.4 then on the next read, read the string qwerty). Using a \ before a whitespace character will treat it as input (e.g. as df is two separate input strings while as\ df is one).
;	Terminator	Destroys an IP
m	Mana	Pushes the current mana value onto the stack
F	Fizzle	Deducts 1 mana from the IP
M	Min Mana	Acts as a threshold barrier. The top value of the stack is popped and compared to the IP's mana. If the mana is greater than the popped value, the IP advances. Otherwise the value is pushed back.
\ / | _ #	Reflectors	Changes the direction of an IP
U D L R	Direction	Changes the pointers direction UP, DOWN, LEFT, RIGHT respectively. Can also use ↑ ↓ ← →
:	Duplicator	Duplicates the top value on the stack
~	Pop	Pops the top value off the stack and discards it
{ }	Rotate Stack	Rotates the entire stack left or right respectively
S	Swap	Swaps the top two values of the stack
s	Swap N	Pops a value off the stack, then pops that many values off the stack, rotates them right one, and pushes them back. (e.g. if your stack is [1,2,3,4,3], calling s results in [1,4,2,3]). See also the Swap modifier
r	Reverse	Reverses the stack
l	Length	Pushes the current length of the stack onto the stack
o	Sort	Pops ValueTypes off the stack until empty or a non-value is found (which is pushed back onto the stack). Sorts these values and pushes them back so that the smallest is on the top of the stack. Requires and consumes n mana where n is the size of the stack minus 10.
[	Pop stack	Pop x off the stack and create a new stack, moving x values from the old stack onto the new one (maintaining the same order). The new stack is completely isolated from the previous one, and an arbitrary amount of stacks can be created on top of each other. Costs 1 mana.
[	Push stack	Remove the current stack, moving its values to the top of the underlying stack. If the current stack is the last stack, ] simply empties the stack.
y	Delay	IP NOPs and does not advance once. See also the delay modifiers.
=	Equals	Pops x and y and pushes 1 if they are equal, 0 otherwise
( )	Less and Greater	Less than and Greater than respectively. Pushes 1 if true, pushes 0 otherwise
!	Trampoline	Skips the next instruction
?	Conditional Trampoline	Pops the top value of the stack. If it is non-zero (or non-null for reference types), skip the next n instructions where n is the popped value (if numeric)
V	Vector3	Pops three values x,y,z off the stack and pushes a resulting Vector3 onto the stack
j	Distance	Pops two GameObject or Vector3 off the stack and computes their distance
'	Character literal	Next cell is read as a literal character
"	Strign literal	IP enters reading mode and reads all cells as characters and concatenates them into a string on the top of the stack until another " is encountered. If the top of the stack is not a string, a new string is pushed onto the stack.
`	Character literal (continuous)	IP enters reading mode, pushing all cells onto the stack as characters until another ` is encountered.
k	To Char	Pops the top value off the stack and converts it to a Character
n	To Number	Pops the top value off the stack and converts it to a double (if it is a value type) or tries to parse it as a double (if it is a string)
q	Concatenate	Pops two values off the top of the stack x and y and concatenates them together as yx and pushes them back onto the stack.
u	Uncat	Pops a value x off the stack. If it is a string it peeks at the next value on the stack. If it is a character it is popped y and performs x.Split(y). Otherwise it decomposes the string into characters and pushes them back onto the stack in order. If x was instead a Vector, it is decomposed into three floats, pushed onto the stack in x, y, z order.
I J H L	Fork	Pops a value x off the stack. Spawns a new pointer in the indicated direction (I-up, J-down, H-left, K-right) with x mana. Requires x mana, consumes x-1 mana. Can also use ↤ ↦ ↥ ↧
T	Transfer Stack	If this is the only IP on this cell or it has no stack, the IP does nothing and does not advance. Otherwise, it pops a value x (cast to int), then pops x items off its own stack and transfers these values to all other IPs on this cell (they end up in the same order they were originally in). Stack underflow still transfers the items that did exist (although the source IP is still terminated). After a transfer has occurred, held IPs will 'skip', allowing them to advance next cycle. Note that if IPs are facing the same direction, they will be merged. See also the Swap modifier.
B	Branch	Pops y and x from the stack and causes the IP to jump to the position (x,y) on the program grid and continue executing from there. The coordinates of the return point (where the IP would have been if it had not jumped) are pushed to the top of the stack. If a direction modifier is applied to this rune, it takes effect before the jump. This effectively allows for the creation of functions. See also the directional modifiers.
E	Eval	Pops a string from the IP and executes it as if it was a Runic program. This IP is frozen in place until the Eval context terminates (each update tick the IP recieves causes 1 update tick in the Eval context). Costs an amount of mana equal to ln(size-5)^2, where size is the length of the string to be Evaluated (min 0). See also the Swap modifier.
w	Write	Aka reflection. Pops a char c, and values y, and x from the stack and writes c to the program grid at (x,y). If x and y are not both value types (or don't exist), the IP's own location is used, and x and y are returned to the stack (if they exist). If c is a modifier (see below) it is written to the modifier grid instead of the execution grid. Costs 1 mana.

Unity specific commands

These are in flux and will be crushed down into a single command like Math. Modifiers will be pushed to the stack alongside their command counterparts in all three reading modes (in char and char-continuous, it will be pushed as a separate object after the command rune).

Rune	Name	Description
Q	Nearby Objects	Pops a value x off the stack and calls Physics.OverlapSphere(selfPosition, x) pushing each returned GameObject onto the stack. Requires a minimum of x+1 mana to execute and consumes x mana.
N	Name	Pushes the name of a popped GameObject onto the stack
t	This	Pushes the GameObject representing this onto the stack (i.e. the GameObject the script is functionally running on)
G	Get GameObject	Pops a string off the stack and queries the ObjectRegistry for a value. Pushes the result.
O	Instantiate Ojbect	Pops a Vector x and GameObject y and spawns a clone of GameObject y at position x. Pushes the clone onto the stack.
x	Position	Pushes the Vector3 location of a popped GameObject onto the stack
	IsEnemy?	Peeks at the top of the stack x and pushes 1 if x has the same layer tag as this
h	Harm	Pops two objects off the stack, x and y, if y is a GameObject then if it is an entity, x damage is dealt to it. If it is a temporary object of some kind, then it is destroyed (the object handles its own destruction, with the damage value as a paramter, different objects may behave differently).

Modifiers

Modifiers are Unicode Combining diacritical marks. These marks either slightly tweak the effect of a given command rune or otherwise alter the behavior of the instruction pointer. Note also the byte penalty for using these modifiers.

Rune	Name	Description
̂ ̌ ᷾ ͐ ̭ ̬ ͔ ͕	Direction	Changes the direction of the IP to the indicated facing. Both above and below diacritical marks work the same and are provided for sake of visibility.
̇ ̈ ̣ ̤	Delay	Adds an amount of delay to the IP, stopping it for a certain number of update cycles (similar to the y command). Values are 1, 2, 4, and 8 respectively.
̺ ̪	Truncate Stack	This modifier will remove items from an IP's stack until the stack fits within the maximum amount allowed by the IP's current mana (this occurs after execution and before the stack-too-large fizzling). Truncates from the top and bottom respectively.
͍	Switch/Swap	When applied to the Eval rune, this causes the eval context to use the executing IP's stack as input and output (pushing and popping from the top as normal). When applied to the swap-N rune, the popped collection is rotated left instead of right. When applied to the Transer stack rune, the IP pulls from the other IPs instead of pushing to them.
͏	Blank Modifier	This non-rendering mark when written using reflection will clear a modifier character
̀ ́ ̍ ̄ ̖ ̗ ̩ ̠ ̊ ̻	Reflectors	These modifiers act like reflectors, taking effect after the primary rune is executed. Above and below variants available for all types of reflectors, listed in order: \\ / `

Any popped object that does not match the expected types is discarded, and the executed command is computed as best as possible (e.g. popping (3,0,0) and 5 off the stack when computing a distance d will result in a 3 being pushed onto the stack as a distance of (3,0,0) is 3 units: effectively results in pushing the vector's own magnitude as the 5 is ignored).

Any attempted pop off of an empty stack terminates the IP.

IPs that advance off the edge of the program (in any direction) are moved to the far edge. In this way >1$ will print an endless series of 1s.

Programs are terminated after 10000 execution steps in the event of infinite loops.

Sample programs:

Hello World

Simple:

>"Hello World!"$;

With IP redirection:

>"Hello"' q\
 ;$"!dlroW"/

With two instruction pointers:

>"Hello"$;
>" World"$;

Other examples

>>55+55++M4$; prints 4 exactly once (two IPs are created but cannot pass the M command until they merge and have 20 mana: the value on their stack

>>55+55++4$; prints 4 twice (both IPs reach the 4 and print it)

>>55+55++:M$; prints 20 once (again the two IPs need to merge before being able to pass the M command. Before executing M the combined IP will have a stack of [20,20] due to the : duplicate command, so after M it prints the single value left on the stack)

This program:

 v$
>31+$;
 2^
 +
 $
 ;;

Has the output 1,5,4: the lower right IP reaches its $ first, while the top IP is created first (and so its $ is processed in the same tick as, but before, the leftmost IP's $).

>4Qtd$; prints the distance between the self-object and one other GameObject within radius 4 (in the sample scene this is 3.162278 and an empty stack)

"3X4+kSq$; is a quine.

TODO:

• Various other Unity GameObject or Physics tasks (this is primary for using the language as enchantments on RPG gear:
  • event entry points,
  • object instantiation
  • IFF
  • Raycasting
• Register(s) (e.g. ><>'s & operator)
• Better error handling (prevent crashes, terminate execution when running infinitely, etc)