semantic-source VS milewski-ctfp-pdf

One production example I know: GitHub code navigation is written in Haskell https://github.com/github/semantic

ah, easy. it's because support has not been added into https://github.com/github/semantic which is the tech that powers the GitHub UI. Adding support is pretty easy/mainly glue code [1] that imports the tree sitter API.

[1] https://github.com/github/semantic/blob/793a876ae45d38a6bd17...

GitHub used Haskell for implementing Semantic, a command-line tool for parsing, analyzing, and comparing source code.

As far as engineering effort, you can read this GitHub comment for an overview of where we’d like to take the project in the future. The tl;dr here is that the open sum type view of the world made it very concise to fold over syntax trees (since such a view of data is ultimately unityped, recursion schemes Just Work), but the tradeoff thus associated—namely, that you have to parse a concrete syntax tree into an open-sum view (a complicated and painful-to-read process), that you can never really be sure how a given syntax tree is shaped, and that the types don’t help you nearly as much as they could—proved to be too onerous to deal with. Going forward, we’re generating syntax types from the AST once per target language, and working on an abstraction (probably via this generated code; I made five separate efforts at using Generics for this, and failed every time) that recovers at least some of the convenience of recursion schemes. It turns out that recursion schemes over a mutually recursive syntax tree—as pretty much every language’s syntax trees are, in practice—are pretty much an unsolved problem, especially when extended to languages like TypeScript, which have hundreds of different syntax nodes.

Meanwhile their Tree-Sitter-based semantic parser[1] looks abandoned. There is even rotting for years pull request[2] adding support of the same stack graphs into it.

[1] https://github.com/github/semantic

[2] https://github.com/github/semantic/pull/535

The semantic team at GitHub uses it for statically analyzing the dozens of languages that end up in GitHub repositories: https://github.com/github/semantic/blob/eaf13783838861fe5eb6cd46d59354774a8eb88d/docs/why-haskell.md

Yesterday I was looking for some examples of projects using tree-sitter (which is C) when I found GitHub's semantic, used to analyze and compare source code, and written in Haskell: https://github.com/github/semantic/

>> He has to be able to think in terms of conceptual hierarchies that are much deeper than a single mind ever needed to face before. Compared to that number of semantic levels, the average mathematical theory is almost flat.

> ... is he being unrealistic about programmers here, or does he not have exposure to what a mathematician would consider Mathematics?

As with any sweeping statement, Dijkstra's assertion is not universally applicable to all programmers. However, for some definition of sufficiently skilled programmer, it is correct if one considers the subset of mathematics applicable to provably correct programs. To wit:

https://bartoszmilewski.com/2014/10/28/category-theory-for-p...

Category theory was a godsend from Milewski, esp. his PDF is great! https://bartoszmilewski.com/2014/10/28/category-theory-for-p...

Maybe you can add a little and offer ressources from your background?

I recently started reading Bartosz Milewski's Category Theory for Programmers[0] and while it's less about Haskell directly and more about the ideas behind it, I found it did a much better job at explaining Haskell to me than any other introduction I read before. At least I'm able to appreciate Typing the Technical Interview[1] now. :-)

[0]: https://github.com/hmemcpy/milewski-ctfp-pdf

[1]: https://aphyr.com/posts/342-typing-the-technical-interview

Category Theory for Programmers by Bartosz Milewski (https://github.com/hmemcpy/milewski-ctfp-pdf/releases)

Strangely similar name to the well-known 'Category Theory for Programmers'

https://github.com/hmemcpy/milewski-ctfp-pdf

There's this, but the programmer doesn't have to be working:

https://bartoszmilewski.com/2014/10/28/category-theory-for-p...

Milewski's "Category Theory for Programmers".