gotoLang

A programing language where the only control flow is goto expr

Example program

bottles = 99;
s = "s";
OUTPUT (STR) bottles + " bottle" + s + " of beer on the wall,";
OUTPUT (STR) bottles + " bottle" + s + " of beer.";
OUTPUT "Take one down, pass it around,";
bottles = bottles - 1;
s = (bottles > 1) * "s";
GOTO 5 * (bottles == 0) + 8;
OUTPUT (STR) bottles + " bottle" + s + " of beer on the wall.";
OUTPUT "";
GOTO (bottles > 0) + 10;
GOTO 12;
GOTO 2;
OUTPUT "No bottles of beer on the wall.";

Requirements

• Python 3
• Virtualenv

Installation

git clone https://github.com/aDotInTheVoid/gotoLang.git
virtualenv -p python3 venv
source venv/bin/activate
pip3 install ply

Usage

python3 gotoLang.py path/to/program.goto

Writing Programs

all gotoLang keywords are uppercase.

Program Structure

A program is a list of statements separated by semicolons. There are 3 types of statements:

• IO Statements
• GOTO Statements
• assign_statement

IO Statements

Input

INPUT some_var_name

Assigns some_var_name to a line read from stdin excluding the \n

Output

OUTPUT expr

Prints the value of expr to stdout

GOTO Statements

GOTO expr

normally statements are executed sequentially. However after the execution of a GOTO Statements, the next statement executed will be the exprth statement of the program (starting at 0, of course). If expr is not an integer, or out of range, this is a error.

Assign Statements

id = expr

sets id to the value of expr

Writing expressions

Primitives

Numbers

Must match r"""[0-9]+(\.[0-9]+)?""" Numbers are stored in base 10

Strings

Must match r"""\"([^\\\n]|(\\.))*?\""""

Variables

Must match r"""[a-zA-Z_][a-zA-Z_0-9]*"""

Operators

Operators generally work like c. They can be nested with parenthesis ((,)).

Operators are listed from highest to lowest precedence.

Operator	Symbol	Precedence	Associativity
Exponential	^	1	Right
Unary Plus	+	2	None
Unary Minus	-	2	None
Logical Not	!	2	None
Integer Cast	(INT)	3	None
Bool Cast	(BOOL)	3	None
Float Cast	(FLOAT)	3	None
Multiplication	*	4	Left
Division	/	4	Left
Modulo	%	4	Left
Addition	+	5	Left
Subtraction	-	5	Left
Less Than	<	6	Left
Less or Equal	<=	6	Left
Greater Than	>	6	Left
Greater or Equal	>=	6	Left
Equal to	==	7	Left
Not Equal to	!=	7	Left
Logical And	&&	8	Left
Logical Or	||	9	Left