ast-grep VS difftastic

This article illustrates the usage of ast-grep, a tool designed to locate and substitute patterns in your codebase, towards easing your migration to React 19.

This looks great, thanks for building and sharing it.

Interested folks may also want to check out ast-grep:

https://github.com/ast-grep/ast-grep

ast-grep is a command-line tool that lets you search and transform code written in many programming languages using abstract syntax trees (ASTs). ASTs are data structures that capture the syntactic and semantic structure of source code. With ast-grep, you can write patterns as if you are writing ordinary code, and it will match all code that has the same syntactical structure. And if you need more power, you can use YAML, a rule system that allows you to write more sophisticated linting rules or code modifications.

I really like this - it means the tool is available to people with familiarity of any of those four distribution mechanisms.

You can also download pre-built binaries from their releases page: https://github.com/ast-grep/ast-grep/releases/tag/0.14.2

On top of that, they offer API bindings for it in three different languages:

- Rust (not yet stable): https://docs.rs/ast-grep-core/latest/ast_grep_core/

- JavaScript/TypeScript: https://ast-grep.github.io/guide/api-usage/js-api.html

- Python: https://ast-grep.github.io/guide/api-usage/py-api.html

It's rare to see a tool/library offer this depth of language support out of the box.

Is there an open source library that does this? Maybe something on top of ast-grep

i want a diff tool that shows me exactly which tokens have changed, and which haven't, regardless of how they are laid out.

These already exist: https://github.com/Wilfred/difftastic

when we get that, then we should get even less merge conflicts.

Counterintuitively, that is not the case. AST-merge is a much, much, much, much, much harder problem than AST-diff.

https://github.com/Wilfred/difftastic?tab=readme-ov-file#can...

The fact that diffs can be used to drive a 3-way merge is in fact an accidental property that arises due to the sheer crudeness of the diff format. As soon as you start using more-sophisticated diff formats, solutions to "the diff problem" no longer lead directly to solutions to "the merge problem".

Yes there is an `—-override` option you can use to specify the language in which a file should be parsed.

https://github.com/Wilfred/difftastic/blob/master/CHANGELOG....

Use the fantastic difftastic instead of git's diff. https://difftastic.wilfred.me.uk/

  [alias]

difftastic provides similar capabilities in a free tool based on treesitter

difftastic? https://github.com/Wilfred/difftastic

If you're looking for a VS Code extension or a GitHub app, check out https://semanticdiff.com/. I'm a co-founder of this project.

If you prefer a CLI tool, check out https://github.com/Wilfred/difftastic. It supports more languages, but doesn't recognize when code has been replaced by an equivalent version ("invariances"). So it will show some changes (e.g. replacing a character in a string with an escape sequence) even though they are technically equivalent.

Shameless plug: I've written difftastic[1], a tool that builds ASTs and then does a structural diff of them. You can use it with git too.

It's an incredibly hard problem though, both from a computational complexity point of view, and trying to build a comprehensible UI once you've done the structural AST diff.

[1]: https://github.com/wilfred/difftastic

There is a diff tool called difftastic: https://github.com/Wilfred/difftastic

The idea is that it does not show diff based on text change, but on syntastic meaning. For that, it uses tree-sitter.

I think it still shows the trailing comma in the situation as shown in the article, but it's quite different experience than the standard text based diff.