What do you think about the draft?

keleshev · July 16, 2020, 6:44am

@Apos yes, the motivation was just to show a bit of assembly. Hello-world is a classic, but I wanted to include some simple instruction like add and mov as well. I will think of another example/explanation.

Also, I plan to change the Taste of assembly section: instead of numbers in the code (/* 1 */) that are referenced in the text, I want to present full code listing, and then repeat relevant instructions intertwined with explanations.

gmarik · July 18, 2020, 4:07pm

p96: is double negative here necessary?

So, why not pop the return address not back into lr, but directly into pc?

p111: is it worth pointing out that “improvement” means trading readability for brevity?
Because, as a reader/student, the “pre-improvement” version is easier to follow than the “improved” one.

We can do precisely that, but there are few improvements that we can make.

keleshev · July 18, 2020, 3:42pm

@gmarik, you are pretty far into the book! What do you think about the chapters so far?

gmarik · July 18, 2020, 4:02pm

so far so good!
looking forward to getting to the coding part, and actually testing my understanding.

Apos · July 19, 2020, 3:45am

7.19 last paragraph:

conditionl execution

I found some other ones, but I forgot to save them. Now I’m in chapter 8.

Apos · July 20, 2020, 7:50pm

Page 116:

whenever we encounter and identifier node

and should be an.

Apos · July 20, 2020, 7:51pm

I finished the book. Now I’m at the point where I can code something.

keleshev · July 20, 2020, 7:52pm

@Apos Congrats! Let us know how it unfolds!

Apos · July 27, 2020, 6:03am

In the code for the baseline compiler, there’s this line:

github.com

keleshev/compiling-to-assembly-from-scratch/blob/136b382f148ca4899bf27069c118ea44ea5775f7/compiler.ts#L56



static regexp(regexp: RegExp): Parser<string> {
  return new Parser(source => source.match(regexp));
}

static constant<U>(value: U): Parser<U> {
  return new Parser(source => new ParseResult(value, source));
}

static error<U>(message: string): Parser<U> {
  return new Parser(source => { throw Error(source.string.slice(source.index)) });
}


or(parser: Parser<T>): Parser<T> {
  return new Parser((source) => {
    let result = this.parse(source);
    if (result)
      return result;
    else
      return parser.parse(source);

You pass an error message, but it’s never used. Also that code is different from what I see in the book.

keleshev · July 27, 2020, 4:31pm

Yeah, in the book it says:

return new Parser(source => { throw Error(message) });

As it should. In the repo what you see is a left-over from a time I was debugging the parser. For that, instead of printing a message, I printed the source starting from the current location (source.index) as a way to see where the parser encountered this error. I will change it back to throw Error(message) in the repo.

jdh30 · August 16, 2020, 6:35pm

I love it! Am a third of the way through the book and I’ve read the entire (incomplete) OCaml source code.

My only gripe is the implementation languages but I’d struggle to recommend a better one. Only one thing for it: we must invent a better language!

keleshev · August 16, 2020, 8:56pm

@jdh30 I’m glad you liked it! And I’m especially pleased to hear it from the author of The OCaml Journal that I used to read.

Yeah, as I say, TypeScript is probably nobody’s favorite, but I was surprised to find it half as bad as I thought. I was struggling to pick between JS, Python, and C#, and thought that TypeScript might not be a bad compromise.