CStart Language

CStart is a simple, interpreted programming language designed for educational purposes. It implements core programming concepts like variables, arithmetic operations, conditionals, and loops in a straightforward syntax inspired by C-style languages.

Features

• Variables: All variable names must start with 'c' (e.g., csum, cvar, cresult)
• Arithmetic Operations: Basic operations like addition (+)
• Comparison Operators: Support for < and > operators
• Control Structures: If-else statements and for loops
• Code Blocks: Enclosed in curly braces {}
• Persistent Environment: Variables maintain their values between expressions

Language Syntax

Variables and Assignment

cvar = 42;     // Assign a value to a variable
csum = cvar + 5;  // Use variables in expressions

Arithmetic

5 + 3          // Basic addition
cvar + 10      // Add a value to a variable

Conditionals

if (cvar > 5) {
  cresult = 1;
} else {
  cresult = 0;
}

Loops

for (ci = 0; ci < 5; ci = ci + 1) {
  csum = csum + ci;
}

Implementation Details

The CStart interpreter follows a standard 3-step process:

1. Tokenization (Lexer): Converts source code text into tokens
2. Parsing: Converts tokens into an Abstract Syntax Tree (AST)
3. Evaluation: Executes the AST to produce a result

The interpreter maintains a persistent environment, allowing variables to retain their values across multiple interpret calls.

Running CStart

Installation

bun install

Running the Example Tests

bun run index.ts

Interactive REPL Mode

Start an interactive session where you can type CStart code and see immediate results:

bun run index.ts --repl

In REPL mode, you can enter code line by line, and variables will persist between commands. Press Ctrl+C to exit.

Example Programs

Calculate Sum of Numbers 0-4

csum = 0;
for (ci = 0; ci < 5; ci = ci + 1) {
  csum = csum + ci;
}
csum;  // Returns 10 (0+1+2+3+4)

Check if a Number is Greater Than 5

cval = 7;
if (cval > 5) {
  cresult = "greater";
} else {
  cresult = "less or equal";
}
cresult;  // Returns "greater"

Limitations

• Only supports numeric values
• Variable names must start with 'c'
• Limited set of operators and control structures
• No function definitions

Future Enhancements

• Support for additional operators (-, *, /)
• Function definitions and calls
• More data types (strings, arrays)
• Enhanced error handling

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This project was created using Bun. Bun is a fast all-in-one JavaScript runtime.