cs-lox

A C# implementation of a Lox interpreter (adapted from jlox, credit to "Crafting Interpreters" (book, repo) by Robert Nystrom)

Language Tweaks

• Language supports nill equality comparison

var a = nil;
var b = nil;
print a == b;
>> True
var c = "not nil";
print a == c;
>> False

• Static methods are supported:

class Greeter{
  class SayHello(){
      print "Hello, I am a static method."
  }
}
Greeter.SayHello();
>> Hello, I am a static method.
var a = Greeter();
a.SayHello();
>> Hello, I am a static method.

• "Getter" propeties are supported:

class Person{
  init(name, surname){
      this.name = name;
      this.surname = surname;
  }
  fullname{
      return this.name + " " + this.surname;
  }
}

var john = Person("John", "Smith");
print john.fullname;
>> John Smith

Furthermore, a compile-error is thrown if the getter never returns a value.

• Other features: ternary conditional (a ? b : c), comma operator support, breaking out of loops, C-style block comments ( /*...*/ )

Implementation Notes:

Statements and State

• jlox uses the Void type for its Statement Visitor:

class Interpreter implements Expr.Visitor<Object>,
                            Stmt.Visitor<Void> {

 void interpret(Expr expression) { 

C#, however, does not allow this, so I instead opted to use a Unit return type (I used a handy one I saw in UniRx).

Functions

• jlox uses an anonymous object to implement the native 'clock' function. However, C# does not allow anonymous types to implement interfaces, so I manually created a separate Clock type.