Flowistry for JavaScript / TypeScript?

[karlhorky]

Hi there, first of all, thanks for creating Flowistry, really cool idea!

Was wondering if it would be possible / simple to apply this to other languages like JavaScript and TypeScript (or if another extension already exists for JS/TS).

Would be amazing to be able to use this, also in teaching!

[willcrichton]

The basic idea is usually called program slicing, of which there are a litany of algorithms. For example, code coverage is a form of dynamic slicing.

The specific algorithm used in Flowistry cannot be easily replicated for other languages, because it is designed to use unique aspects of Rust, namely ownership types.

[karlhorky]

Ok, thanks for this @willcrichton!

I searched the VS Code extensions Marketplace, but I didn't see anything that does the same as Flowistry (but maybe I'm using the wrong terms - I searched for "program slicing", "focus related", "dependent code", and some others).

One thing that I did realize is that I often use the built-in feature of VS Code which does some kind of similar type-aware highlighting for identifiers (although no dimming of code). So at least there is that! 🙌

https://user-images.githubusercontent.com/1935696/189691471-37bed75f-78f2-4f20-8fc0-395b68ee1161.mp4

[karlhorky]

I'm assuming I should close this issue, since I imagine you don't plan to support JS/TS with Flowistry, right?

[karlhorky]

As a (almost unrelated) side note, I also use the Chrome extension Selection Highlighter by @neaumusic to achieve something similar when browsing on the web as well (not only useful for code, also good for speed-reading articles, to extract the important bits and skip over filler):

[willcrichton]

I searched the VS Code extensions Marketplace, but I didn't see anything that does the same as Flowistry (but maybe I'm using the wrong terms - I searched for "program slicing", "focus related", "dependent code", and some others).

Yes, to my knowledge Flowistry is the only extension of its kind right now. In my PLDI paper, I talk a little bit about what makes slicing hard (specifically modular static slicing), and why you need Rust (or really ownership types) to do it. You can find the paper here: https://arxiv.org/pdf/2111.13662.pdf

As you noted, most IDEs support direct syntactic or type-based reference, essentially extensions of "jump to definition". But as an example of what you need for Flowistry-style analysis: there is no IDE operation for "find all values of this pointer". Slicing requires a more semantic model of the program than syntactic scopes or types.