BASICALLY

A modern BASIC interpreter written in BASIC.

BASICALLY is an experimental programming language project focused on structured BASIC syntax, simplicity, and eventually creating small 2D games.

Current Status

Early development. BASICALLY 0.7 introduces WHILE / WEND loops, building on BASICALLY 0.6's conditional branching with IF, ELSEIF, and ELSE.

Implemented Features

• Reading and executing BASIC source files
• PRINT statements for text and variable values
• String and integer variables
• Variable declarations using DIM
• Integer arithmetic: addition, subtraction, multiplication, and division
• Arithmetic expressions with parentheses and operator precedence
• Unary positive and negative operators
• Comparison operators: =, <>, <, >, <=, and >=
• IF / END IF conditional blocks
• ELSE alternative branches
• ELSEIF conditional branches
• Nested conditional blocks
• WHILE / WEND loops
• Nested loops
• Conditional branching inside loops
• Validation for unmatched WHILE and WEND statements
• Apostrophe comments and blank lines
• Basic error handling for invalid conditions and division by zero

Example

DIM playerHealth AS INTEGER
DIM playerGold AS INTEGER

playerHealth = 75
playerGold = 0

IF playerHealth > 100 THEN
    PRINT "Expert player!"
ELSEIF playerHealth > 0 THEN
    PRINT "Player is alive!"

    IF playerGold > 0 THEN
        PRINT "Player has gold!"
    ELSE
        PRINT "Player needs more gold."
    END IF

ELSE
    PRINT "Game over!"
END IF

Loop Example

DIM count AS INTEGER

count = 1

WHILE count <= 5
    PRINT count
    count = count + 1
WEND

Expected output:

1
2
3
4
5
Program finished.

Requirements

• Linux
• FreeBASIC compiler (fbc)

Building

Compile the interpreter:

fbc basically.bas -x basically

Run a BASICALLY program:

./basically your-program.bas

Running Tests

The tests/ directory contains BASIC programs for testing interpreter features.

Run the regression tests:

./basically tests/else.bas
./basically tests/elseif.bas
./basically tests/nested-conditions.bas
./basically tests/while.bas
./basically tests/nested-while.bas
./basically tests/while-conditions.bas
./basically tests/unmatched-while.bas
./basically tests/unmatched-wend.bas

The unmatched-loop tests should report errors rather than execute normally.

Planned Features

• Functions and reusable procedures
• Improved error messages and syntax validation
• Self-hosting

Contributing

BASICALLY is an experimental project, and contributions, bug reports, feature ideas, and testing are welcome.

See CONTRIBUTING.md for contribution guidelines.

License

BASICALLY is released under the MIT License.