I'm following along with the book, Crafting Interpreters, but I'm implementing jlox in C# instead, as I thought it would help me understand the code better if I had to do some amount of porting. I am running into language specific issues though, particularly, I believe, with how C# handles null.

After implementing the resolver from chapter 11, my interpreter can no longer handle for loops (and probably while loops too, though I didn't test this).

The resolver does not seem to properly store the location of the variable declaration in the for loop in its dictionary. This leads to it passing the wrong 'distance' to the interpreter.

Here's an example:

for (var i = 0; i < 10; i = i + 1) {
    print i;
}

My interpreter will crash with this code that should be valid, because when it encounters print i it won't be able to find the declaration for i. The next chapter of the book is about classes, so this error is not supposed to be here.

I apologize for the complexity of the code and the low amount of comments, my plan was to complete this part of the book and then reread it and go over and comment all my code so I can understand it better. I've attached a link to the GitHub issue on this post, it has a simple explanation and the stack-trace .NET throws when it encounters a for loop.

Please let me know if you need more information.

I won't be surprised if it turns out to be a very simple mistake, but I will facepalm.

I can't figure out what is going on in my program, I'm having a hard time wrapping my mind around what steps its taking to get to the wrong result.

I have this function which should make my parser ignore C-style comments, ie /* */. When I type /* * */ or any number of * in the comment my program is detecting the * characters inside the comment itself, and when it detects a * it also detects the last /:

	// Handle C-style comments
	private void HandleComment() {
		// Consume until closing characters, multi-line comments are supported
		while (Peek() != '*' && PeekAhead() != '/' && !IsAtEnd()) {
			if (Peek() == '\n') line++;
			Advance();
		}

		Advance();
		Advance();
	}

I figured I would need to Advance() twice in order to consume both the characters that denote the end of the comment.

Peek(), PeekAhead(), Advance() and IsAtEnd() are functions from the book, Crafting Interpreters, here they are:

	// Peek at the next char
	private char Peek() {
		if (IsAtEnd()) return '\0';
		return source[current];
	}

	// Peek after next char
	private char PeekAhead() {
		if (current + 1 >= source.Length) return '\0';
		return source[current+1];
	}

	private char Advance() {
		return source[current++];
	}

	private bool IsAtEnd() {
		return current >= source.Length;
	}

The source variable is just a string that contains the text contents of a file or the input from Console.ReadLine().

I based the comment logic on the string logic here:

	// Handle string lexemes
	private void HandleString() {
		// Consume until closing quote, multi-line strings are supported
		while (Peek() != '"' && !IsAtEnd()) {
			if (Peek() == '\n') line++;
			Advance();
		}

		// Handle unterminated strings
		if (IsAtEnd()) {
			DotLox.Error(line, "Unterminated string.");
			return;
		}

		// Consume
		Advance();

		// Tokenize string and store value without quotes
		string value = source[(start+1)..(current-1)];
		AddToken(TokenType.STRING, value);
	}

I almost forgot to share this crucial bit of logic here:

	private void ScanToken() {
		char c = Advance();

		// Match characters to tokens
		switch(c) {

			// Division and comments
			case '/':
				if (Match('/')) {
					// Consume comment but don't turn it into a token
					while (Peek() != '\n' && !IsAtEnd()) Advance();
				} else if (Match('*')) {
					// Handle C-style comments
					HandleComment();
				} else {
					// Turn lone slash into a token
					AddToken(TokenType.SLASH);
				}
				break;
                }
       }

I wrote a blog post about me getting in to FSharp web application development, but am having issues deciding how I want the data access to look. I'm very much open to feedback!

They finally did it!

"A sense of lost elegance" is surely an interesting statement. What do you think? Have the many new features added to C# in recent versions increased productivity, or have they made the language more difficult to teach and learn?

I made another oopsie, I mean, Open Sourcie. :3

Remember Haskell's newtype? Or F# type abbreviations?

Well, newtype is a package that lets you use similar semantics in #CSharp for a large number of types, including the ability to add semantics and extension-like methods to your own derived types.

MIT-Licensed, go wild!

https://github.com/outfox/newtype

https://www.nuget.org/packages/newtype