bear

Not to be confused with Bear Food.

bear is a two-dimensional esoteric language. Programs in bear are obstacle courses for bears which are coerced to perform work when they step on special cells.

State

In this language bears hold state in baskets. Baskets are a dynamic array of cells which are integer values. In addition, each bear holds a singular value in its mouth and another swap value in its paw.

There is one selected value in a bear's basket. Values can be inserted and popped at the end of the dynamic array. The dynamic array's size cannot become less than 1. The initial value of the first cell of the dynamic array is 0, the bear holds 0 and the swap of the bear is also 0.

Runtime

Bears start at predetermined cells marked by a bear character (in askii_bear the bear character is '#'). Afterwards they start following the closest food they can reach and they haven't eaten immediately before. There is replenishable (or infinite) food and perishable (one-time) food. If there isn't any reachable food a bear gives up and the program terminates (in the case of multiple bears the program terminates when all bears have given up).

There is a character that makes a bear enter collect mode. In this mode a set of characters change their functionality.

Syntax

Symbols which do not have a description in collect mode perform the same job as in normal mode. The symbols that perform an arithmetic or bitwise operation store the result of the operation to the integer the bear holds in its mouth.

Character	Normal mode	Collect mode
.	An empty cell.
#	Marks the starting position of a bear. Does nothing afterwards.
>	One way door. Allows the bear to pass only from west to east.
_	One way door. Allows the bear to pass only from north to south.
<	One way door. Allows the bear to pass only from east to west.
^	One way door. Allows the bear to pass only from south to north.
:	A gate that allows the bear to step on this cell if and only if the integer the bear holds in its mouth is the same as the selected integer in is basket. When searching for the next closest food the bear considers all gates open and the check only happens when the bear attempts to move to the cell with the gate.
|	A 'tree'. Blocks a cell.
~	Toggles collect mode.
'	Perishable food.	Left shifts the integer in the bear's mouth.
@	Replenishable food.	Left shifts the integer in the bear's mouth and adds 1 to it.
?	Inputs a string (from stdin). The characters of the string are converted to integers and are appended to the end of the bear's basket.	Inputs a number. Appends it to the end of the bear's basket.
!	Interprets the selected integer in the bear's basket as a character. If it is a valid UTF-8 character, outputs (to stdout).	Outputs the selected integer in the bear's basket as a number.
"	Changes the selected integer to the next cell in the dynamic array. Loops back around if at the end.	Changes the selected integer to the previous cell in the dynamic array. Loops back around if at the beginning.
+	Adds the selected integer to the one the bear holds in its mouth.	Subtracts the selected integer from the one the bear holds in its mouth.
*	Multiplies the integer the bear holds in its mouth by the selected one.	Divides the integer the bear holds in its mouth by the selected one.
&	Bitwise AND the selected integer and the one the bear holds in its mouth.	Bitwise OR the selected integer and the one the bear holds in its mouth.
-	Flip the bits of the integer the bear holds in its mouth.
%	Swap the integer the bear holds in its mouth with the one in its paw.
=	Set the integer the bear holds in its mouth to the selected integer in its basket.	Set the selected integer in the bear's basket to the one the bear holds in its mouth.
;	Append the integer the bear holds in its mouth to the end of the dynamic array.	Remove the last integer in the dynamic array if the length of the array is at least 2.

Examples

Cat

#?.
||_
@<"
_|^
..!
:||
_|.
@..

Parsing

Characters that are not part of the syntax of the language should be ignored. If the lines of the input to be interpreted are "jagged", empty cells should be appended to each line that the area the bear explores is rectangular in nature.

State of the language

This language is under construction and in the future may receive new features.

External resources

• Interpreter by the creator written in rust: interprebear.