basil

a dynamically typed, interpreted scripting language (and interpreter written in C#!)

based on Bob Nystrom's lox language from Crafting Interpreters

...ok, but why?

Basil is a WIP dynamically typed, interpreted scripting language and C# interpreter designed with user-extensibility in mind. Created to be a companion to C# game development environments (notably, Unity), to be used to create powerful debugging and modding tools.

With a simple Native Function Interface, users can create their own Basil functions in C#, making it easy to integrate into other C# environments, and letting the user define how restrictive they want the bridge between C# and Basil to be.

Also, writing an interpreter and designing your own programming language is fun!

⚗ interpreter features

• native function interface
• preprocessing
• lexical analysis
• parsing
• intermediate code generation
• optimization
• code generation

💭 language features

• dynamic typing
• automatic memory management
• data types
• expressions
• statements
• variables
• control flow
• functions
• classes
• inheritance

📝 examples

// fizzbuzz
fun fizzbuzz(start, end)
{
    for (var i = 0; i < end; i++)
    {
        if (i % 3 == 0 and i % 5 == 0) print "FizzBuzz";
        else if (i % 3 == 0) print "Fizz";
        else if (i % 5 == 0) print "Buzz";
        else print i;
    }
}

fizzbuzz(1,15);

🌉 native function interface

Creating Basil functions in C# looks like...

namespace BasilLang.NFI
{
    // The NativeFunction attribute tells the interpreter to add this to its Basil function library

    [NativeFunction]
    public class SayHiFunction : NativeCallable
    {
        // what is the name of this method in Basil?
        public string MethodName => "sayHi";

        // How many arguments does the function have?
        public int Arity()
        {
            return 1;
        }

        //  sayHi("Developer");
        //  will print 'Hello, Developer'
        public object Call(Interpreter interpreter, List<object> arguments)
        {
            Console.WriteLine("Hello, " + arguments[0].ToString());
            return null;
        }
    }
}

🚋 roadmap

• finalize basic language syntax
• add switch statements
• fix continue keyword for for loops
• add list and map types
• add function overloading
• create a serviceable standard library
• optimize tokenizing
• optimize interpreter
• create some tools for using Basil

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crafted with knowledge from Bob Nystrom's Crafting Interpreters