blog: add version 0.39 release note

Author: HerringtonDarkholme

website/blog/new-ver-39.md

@@ -0,0 +1,113 @@
+---
+author:
+  - name: Herrington Darkholme
+search: false
+date: 2025-08-03
+head:
+  - - meta
+    - property: og:type
+      content: website
+  - - meta
+    - property: og:title
+      content: ast-grep new release 0.39
+  - - meta
+    - property: og:url
+      content: https://ast-grep.github.io/blog/new-ver-39.html
+  - - meta
+    - property: og:description
+      content: 'ast-grep 0.39 includes new languages support, better file config and Esquery style kind.'
+---
+
+# ast-grep 0.39 is Here
+
+ast-grep 0.39 is out! This release includes new languages support, better file config and esquery style.
+
+## Esquery Style Kind
+
+ast-grep now supports [ESQuery style](https://github.com/estools/esquery) kind in the `kind` field of the rule configuration. This allows you to write more concise rule in ast-grep. Under the hood, it is equivalent to [relational rules](/guide/rule-config/relational-rule.html) like `has`.
+
+ESQuery is a library for querying the AST using a [CSS style selector](https://developer.mozilla.org/en-US/docs/Learn_web_development/Core/Styling_basics/Basic_selectors) system.
+
+For example, you can write a rule to match all `identifier` nodes that are direct children of `call_expression` nodes like this:
+
+```yaml
+kind: call_expression > identifier
+```
+
+This is equivalent to the following relational rule:
+
+```yaml
+kind: identifier
+inside:
+  kind: call_expression
+```
+
+Currently, ast-grep's ESQuery style `kind` only supports the following selectors:
+
+* node kind: `identifier`
+* `>`: direct child selectors
+* ` `: descendant selector
+* `+`: next sibling selector
+* `~`: following sibling selector
+
+The corresponding relational rules are:
+
+:::code-group
+
+```yaml [direct child]
+kind: call_expression > identifier
+# is equivalent to
+kind: identifier
+inside:
+  kind: call_expression
+```
+
+```yaml [direct child]
+kind: call_expression identifier
+# is equivalent to
+kind: identifier
+inside:
+  kind: call_expression
+  stopBy: end  # note the stopBy
+```
+
+```yaml [next sibling]
+kind: decorator + method_definition
+# is equivalent to
+kind: method_definition
+follows:
+  kind: decorator
+```
+
+```yaml [next sibling]
+kind: decorator ~ method_definition
+# is equivalent to
+kind: method_definition
+follows:
+  kind: decorator
+  stopBy: end  # note the stopBy
+```
+
+:::
+
+If you want to use more ESQuery selectors, please file your use cases in [this ast-grep issue](https://github.com/ast-grep/ast-grep/issues/2127).
+
+
+
+## New Languages Support
+
+ast-grep 0.39 adds support for the following languages:
+
+* [Nix](https://nix.dev/tutorials/nix-language.html) a domain-specific, purely functional, lazily evaluated, dynamically typed programming languages for Nixpkgs and NixOS.
+* [Solidity](https://soliditylang.org/) A statically-typed curly-braces programming language designed for developing smart contracts that run on Ethereum. ($ETH bull run incoming? 🐂)
+
+## `file`  in rule config is relative to the project config file
+
+Previously, the files section appears to be treated as relative to the current working directory from which ast-grep was invoked rather than the dir containing the [sgconfig.yml](/reference/sgconfig.html) file.
+
+This has been changed in 0.39, so now the `files` section is relative to the project config file.
+
+
+## Next Steps
+
+Thanks for reading! If you are interested in the new features, please try them out and let us know your feedback.