--- title: Pyrefly v1.2 is here! | daily.dev description: Pyrefly v1.2 adds native type checking support for attrs classes without requiring plugins, and introduces a standard Bazel integration via a new pyrefly... canonical: https://daily.dev/posts/pyrefly-v1-2-is-here--p1vlysily twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Pyrefly v1.2 is here! | daily.dev og:description: Pyrefly v1.2 adds native type checking support for attrs classes without requiring plugins, and introduces a standard Bazel integration via a new pyrefly... og:url: https://daily.dev/posts/pyrefly-v1-2-is-here--p1vlysily og:image: https://api.daily.dev/og/posts/P1VLYsIly.png og:image:alt: Pyrefly v1.2 is here! og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Pyrefly v1.2 is here! **[Pyrefly: A Fast Python Type Checker and Language Server \| Pyrefly](https://daily.dev/sources/pyrefly)** · 6 min read · 0 upvotes · 0 comments ## Summary Pyrefly v1.2 adds native type checking support for attrs classes without requiring plugins, and introduces a standard Bazel integration via a new pyrefly bazel-check command and the rules_pyrefly package. The release also stabilizes the pyrefly coverage command for tracking type annotation coverage in CI, expands tensor shape checking (still early alpha), and ships numerous type-checking improvements for functools.partial, singledispatch, pattern matching, Pydantic, Django, TypedDict, and Enum. Language server improvements include baseline diagnostics, better hover info, alias-aware auto-imports, and more reliable renames. The release includes 901 commits from 59 contributors, is about 8% faster than v1.1 with 2-4% lower memory use, and closed 137 bug issues. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How do I type-check attrs classes with Pyrefly? As of Pyrefly 1.2, attrs classes are type-checked automatically with no plugin or configuration required. Pyrefly recognizes both the modern API (@define, @frozen, @mutable, attrs.field) and the classic API (@attr.s, @attr.ib, @attr.dataclass), synthesizes __init__ signatures including converter input types, and catches misconfigurations at class creation. _Teams adopting stricter typing for attrs-based codebases can track tooling updates like this on daily.dev._ ### How do I run Pyrefly type checking with Bazel? Pyrefly 1.2 introduces a standard Bazel integration through the pyrefly bazel-check command and the rules_pyrefly package, available on the Bazel Central Registry as version 0.1.0. It uses a Bazel aspect to apply Pyrefly across py_library, py_binary, and py_test targets, reading the Python version from the rules_python toolchain, so projects no longer need custom build logic or wrapper rules. Run it with bazel build --config=pyrefly //path/to/package:target; the integration is still early stage with some import layouts unsupported. _Python teams standardizing Bazel builds can follow integration changes like this via daily.dev._ ### How much faster is Pyrefly 1.2 compared to 1.1? Pyrefly 1.2 is about 8% faster than version 1.1, based on benchmarks across eight projects from Astral's ty_benchmark suite. Memory use also dropped 2% to 4% on tested repositories, alongside 137 closed bug issues covering false positives, crashes, stack overflows, and narrowing improvements. _Developers comparing Python type checker performance can keep tabs on benchmarks like these through daily.dev._ ## Similar posts on daily.dev - [Pyrefly 1.0: A fast, forward-looking Python linter](https://daily.dev/posts/pyrefly-1-0-a-fast-forward-looking-python-linter-k4vukcqpr) · InfoWorld · 0 upvotes · 0 comments - [Pyrefly Now Type Checks PyTorch – PyTorch](https://daily.dev/posts/pyrefly-now-type-checks-pytorch-pytorch-adohlgdfc) · PyTorch · 0 upvotes · 0 comments - [Pyrefly v1.3: More configurability and composable tensor shapes](https://daily.dev/posts/pyrefly-v1-3-more-configurability-and-composable-tensor-shapes-dolihjblt) · Pyrefly: A Fast Python Type Checker and Language Server \| Pyrefly · 0 upvotes · 0 comments - [Adopting Pyrefly as the Python type checker at Google](https://daily.dev/posts/adopting-pyrefly-as-the-python-type-checker-at-google-ixrvzgxi3) · Google Open Source Blog · 0 upvotes · 0 comments - [Pyrefly LSP Integration in PyCharm 2026.1.2](https://daily.dev/posts/pyrefly-lsp-integration-in-pycharm-2026-1-2-5vifkrupr) · JetBrains · 4 upvotes · 0 comments --- Tags: [#python](https://daily.dev/tags/python), [#bazel](https://daily.dev/tags/bazel) [View this post on daily.dev](https://daily.dev/posts/pyrefly-v1-2-is-here--p1vlysily) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Pyrefly v1.2 is here!","url":"https://daily.dev/posts/pyrefly-v1-2-is-here--p1vlysily","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/pyrefly-v1-2-is-here--p1vlysily"},"datePublished":"2026-08-23T12:17:16.306Z","dateModified":"2026-08-23T12:58:37.140Z","description":"Pyrefly v1.2 adds native type checking support for attrs classes without requiring plugins, and introduces a standard Bazel integration via a new pyrefly...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/ce7cceb523e1bdb0e6d2d6310d2d101d?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/ce7cceb523e1bdb0e6d2d6310d2d101d?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Pyrefly: A Fast Python Type Checker and Language Server | Pyrefly","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Pyrefly: A Fast Python Type Checker and Language Server | Pyrefly","logo":"https://media.daily.dev/image/upload/s--Qzw5NpnF--/c_limit,w_256/f_auto,q_auto/v1787487420/logos/pyrefly?_a=BAMAMicg0","url":"https://daily.dev/sources/pyrefly"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/pyrefly-v1-2-is-here--p1vlysily","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"python,bazel","timeRequired":"PT6M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Pyrefly: A Fast Python Type Checker and Language Server | Pyrefly","item":"https://daily.dev/sources/pyrefly"},{"@type":"ListItem","position":3,"name":"Pyrefly v1.2 is here!"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/pyrefly-v1-2-is-here--p1vlysily#faq","mainEntity":[{"@type":"Question","name":"How do I type-check attrs classes with Pyrefly?","acceptedAnswer":{"@type":"Answer","text":"As of Pyrefly 1.2, attrs classes are type-checked automatically with no plugin or configuration required. 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