LarBASIC 💾

Tiny BASIC interactive interpreter with string support.

How to run LarBASIC

Clone this repository and run $ python3 larbasic.py. Of course, Python 3 is required to execute this software.

Available Commands

• REM <anything>: used to write comments.
• LET <expression> = <expression>: used to assign values to variables.
• RUN: used to execute the stored code listing.
• INPUT <expression>: used to accept user input into variables.
• PRINT <expression>: used to print values to the screen.
• CLS: used to clear the screen.
• GOTO <expression>: used to jump the execution to another line.
• IF <expression> THEN <command>: conditional statement.
• END: halts execution of a LarBASIC script.
• EXIT: exits the LarBASIC interpreter.
• LIST: prints the stored code listing to the screen.
• CLEAR: clears the code listing.

LarBASIC is a typed language. Numeric variable names may only contain characters from a-Z and numbers, provided they start with a letter. String variable names follow this same guidelines but must end in a $ character. For example, a variable called foo will be a numeric variable, while a variable called foo$ may store strings.

Expressions work just like in most other programming languages you may know, with the only exception that values and operators must be separated with a space. For example a + b / 8 is a valid expression, while a+b/8 is not.

Available operators are +, -, /, *, ^ (power), % (modulo), ==, !=, <, >, <=, >=, . (concatenation), & (logic and) and | (logic or).

Lines written into the interpreter preceded by a line number (for example 10 PRINT "Hello there!") are not executed immediately, but added to the code listing. You may run all the lines in your code listing by using the run statement. Lines without a line number are executed right away.

Example LarBASIC Listings

10 REM +----------------------+
20 REM | LarBASIC Disan Count |
30 REM +----------------------+
40 PRINT "Enter a number:"
50 INPUT max
60 IF max % 2 == 0 THEN PRINT max . " is even!"
70 LET max = max - 1
80 IF max >= 0 THEN GOTO 60
90 PRINT "Done!"
100 END

10 "foo" . 1 = 19
20 print foo1
30 REM That prints 19

License

LarBASIC and its source code are released under the MIT License.