winget install --id facebook.pyreflyAbout Pyrefly
Pyrefly is a type checker and language server for Python, which provides lightning-fast type checking along with IDE features such as code navigation, semantic highlighting, and code completion. It is available as a command-line tool and an extension for popular IDEs and editors such as VSCode, Neovim, Zed, and more.
What's new in 1.1.1
Release date: June 18, 2026 Pyrefly v1.1.1 is a patch release with a single bug fix. ----- ## 🐛 Bug fixes - #3867: Fixed a regression introduced in 1.1.0 where isinstance() narrowing of a union variable silently stopped working when an earlier sibling branch in the same if/elif/else chain narrowed a different variable with isinstance() and returned. The later narrowing left the union untouched, producing false missing-attribute errors on code that checked correctly in 1.0.0. Thank-you to all our contributors who found these bugs and reported them! Did you know this is one of the most helpful contributions you can make to an open-source project? If you find any bugs in Pyrefly we want to know about them! Please open a bug report issue here.
Version history
| Version | Updated | Notes |
|---|---|---|
| 1.1.1 | Release date: June 18, 2026 Pyrefly v1.1.1 is a patch release with a single bug fix. ----- ## 🐛 Bug fixes - #3867: Fixed a regression introduced in 1.1.0 where isinstance() narrowing of a union variable silently stopped... |