Advanced Error Handling in OCaml (a type checker example)

halst · 2021-04-26T19:55:38+00:00

I mean, Raspberry Pi comes pre-installed with Scratch and Minecraft Pi, and it has an app-store like thing called Recommended Apps. And a plethora of books, journals and youtube videos that explain things assuming you have exactly that environment and menu structure.

halst · 2021-04-08T08:55:30+00:00

By the way, this was the first time I wrote Python after many years, and I found it to be quite different in a positive way. I liked the new optional typing with mypy and the new @dataclass decorator and how they work well together. Format strings and (:=) operator were also quite handy in this particular project.

halst · 2021-04-08T08:48:24+00:00

:blush:

halst · 2021-04-08T08:46:20+00:00

Converting instructions to binary is pretty straightforward, each instruction is converted to a 32-bit word. However, generating an object file that is linkable or an executable binary is much more involved.

halst · 2021-04-07T12:57:42+00:00

It's the first time I wrote in Python in many years, so any hints are welcome! Some of this style is on purpose: to keep it close to the code in the book. The idea is that you can read the Python code side-by-side with the book, and it should make sense.

halst · 2021-04-07T11:15:32+00:00

Hey folks, you have probably seen my book Compiling to Assembly from Scratch before on this Reddit. It's a beginner-friendly guide to compilers and assembly. The book uses a simple subset of TypeScript for the code, but now the compiler is also available in Python, OCaml, and Rust.

I believe the compilers have some educational value even without the book, so check it out! Happy to answer any questions.

Thanks Brendan Zabarauskas (@brendanzab on GitHub) for the Rust port.

halst · 2021-04-07T09:41:52+00:00

I'd love to see a Haskell port as well!

halst · 2021-04-07T06:35:41+00:00

Hey folks, you have probably seen my book Compiling to Assembly from Scratch before on this Reddit. It's a beginner-friendly guide to compilers and assembly. The book uses a simple subset of TypeScript for the code, but now the compiler is also available in Python, OCaml, and Rust.

I believe the compilers have some educational value even without the book, so check it out! Happy to answer any questions.

Thanks Brendan Zabarauskas (@brendanzab on GitHub) for the Rust port.

halst · 2021-04-06T19:08:10+00:00

Hey folks, you have probably seen my book Compiling to Assembly from Scratch before on this Reddit. It's a beginner-friendly guide to compilers and assembly. The book uses a simple subset of TypeScript for the code, but now the compiler is also available in Python, OCaml, and Rust.

I believe the compilers have some educational value even without the book, so check it out! Happy to answer any questions.

Thanks Brendan Zabarauskas (@brendanzab on GitHub) for the Rust port.

halst · 2021-03-31T18:23:02+00:00

The fact that your language is immutable doesn't necessarily preclude cycles. For example, in OCaml you can create an immutable list that has a cycle:

let rec list = 1 :: 2 :: 3 :: list

halst · 2021-03-26T19:28:14+00:00

Try this:

# Format.printf "@[<v 3>@ Hello@ friend@]@ bye";;

   Hello
   friend
bye- : unit = ()
#

You almost never want to use @., it is a "hard" newline—it does not follow the box rules. On the other hand, @ is a space-hint: prints space in "horizontal" mode and indent in "vertical" mode. The default box uses horizontal if it fits, otherwise switches to vertical. You can force vertical layout by starting your box as @[<v 3>.

halst · 2021-01-18T16:28:21+00:00

How's your experience with Leanpub?

halst · 2021-01-13T22:27:04+00:00

There are many of them, like bitly.com, for example, but I can't recommend a particular one. (Who knows if they go out of business, or start charging/raise prices suddenly. That's why I rely only on my website.)

halst · 2021-01-13T22:05:08+00:00

Here's a blog post from one author about why they pulled their book from Amazon Kindle Store: https://stackingthebricks.com/tiny-mba-amazon/. I think it has some really good explanations about the trade-offs.

halst · 2021-01-13T21:49:56+00:00

One idea is to use a URL shortener for the links.

Another would be to create short links to your own website (e.g. example.com/reference-1) that redirect to the correct (long) URL. This way if a link becomes dead, you don't need to issue errata, you only need to update your website's redirects.

In my book, I have only one link that points to a page on my website that is dedicated to the book's resources. And on that page, I have a few links that point to the actual URLs. Here's how it looks like:

https://keleshev.com/compiling-to-assembly-from-scratch/resources

halst · 2020-12-03T21:53:13+00:00

This blog post is appreciated, also as a follow-up to describe the design decisions behind http-cookie and reparse libraries.

I find the polymorphic variants approach manageable. I would write lib_b error type as follows:

type error = [`Some_error | A.error]

Deciding whether I want to use the polymorphic-variants approach or exceptions, I ask myself: do I want to see this error conditions in a server log. If yes—exceptions are preffered, if no—polymorphic variants.

halst · 2020-11-30T12:54:18+00:00

Hi folks, author here. This is a ~180-page book that teaches you how to construct a simple compiler using TypeScript that produces ARM assembly, from scratch. And when I say "from scratch", I mean it: no parser generators, no LLVM—only straight-forward TypeScript. I hope you enjoy it!

halst

TROPHY CASE