--- title: What’s up Python? JSFiddle for Python, f-objects, and... description: A monthly Python roundup covers a new tool called Pystebin, built on Pyodide, that lets developers write and run executable Python snippets directly in the... canonical: https://daily.dev/posts/what-s-up-python-jsfiddle-for-python-f-objects-and-new-built-ins--sf9j56ctg twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: What’s up Python? JSFiddle for Python, f-objects, and new built-ins... | daily.dev og:description: A monthly Python roundup covers a new tool called Pystebin, built on Pyodide, that lets developers write and run executable Python snippets directly in the... og:url: https://daily.dev/posts/what-s-up-python-jsfiddle-for-python-f-objects-and-new-built-ins--sf9j56ctg og:image: https://api.daily.dev/og/posts/Sf9J56cTg.png og:image:alt: What’s up Python? JSFiddle for Python, f-objects, and new built-ins... 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. # What’s up Python? JSFiddle for Python, f-objects, and new built-ins... **[Bite Code](https://daily.dev/sources/bitecode)** · 6 min read · 7 upvotes · 2 comments ## Summary A monthly Python roundup covers a new tool called Pystebin, built on Pyodide, that lets developers write and run executable Python snippets directly in the browser and share them via link, supporting Python 3.9 through 3.14. It also critiques two proposed PEPs: PEP 841, which would add frozen-literal syntax like f{1,2,3} for frozen sets and f{'a':1} for frozen dicts, and PEP 844, which proposes @public and @private decorators plus a public() builtin to manage __all__. Additional notes cover a threading.run() convenience function under discussion, PyPI crossing 2 exabytes of bandwidth in 2026, Mojo going open source, and uv's cache improvements that deduplicate at the file level using blake3 hashing to save about 10% of cache size at a 3-4% cold-install cost. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How does uv's cache deduplication work and what's the performance impact? Uv now deduplicates its cache at the file level by hashing files with the blake3 hash function and storing them in central storage, saving about 10% of total cache size. This costs a 3 to 4% slowdown on cold installs but has no measurable effect on cached installs, and Astral offset the slowdown with an additional optimization shipped alongside it. _Track uv's cache and performance changes on daily.dev before they affect your install times._ ### What is PEP 841 proposing for Python syntax? PEP 841, titled Adding Frozen Syntax to Optimize Immutable Types, proposes built-in syntax for immutable collections, such as f{1, 2, 3} for a frozen set and f{'a': 1} for a frozen dict. Critics note Python lacks a built-in immutable dict until version 3.15, and argue the syntax is confusing alongside f-strings and unnecessary given Python's existing JIT and mutability norms. _Follow evolving Python PEPs like this on daily.dev before they land in a release you depend on._ ### What can Pystebin do and what are its limitations? Pystebin is a browser tool built on Pyodide that lets you write, run, and share executable Python code snippets via a link with no installation required, supporting Python 3.9 through 3.14 and including a virtual file system so sqlite works. It cannot run Tkinter or make network calls, and Pyodide itself is roughly 14MB and considerably slower than native Python. _Developers evaluating in-browser Python tooling can follow projects like Pystebin on daily.dev._ ## Community discussion Top comments from developers on daily.dev. **@agustinbarrientos** · 0 upvotes > I'd pin the exact Pyodide build in every shared Pystebin link so an old snippet can't silently change behavior after an upgrade. **@ahmetozel** · 0 upvotes > The uv cache change is the item with the most immediate effect for anyone running ML containers. Deduplicating at file level with blake3 sounds modest until you count how many images pull the same torch wheel over and over - build cache is one of those costs teams never attribute correctly because it hides inside CI minutes rather than showing up as a line item. On PEP 841, the syntax argument will dominate the discussion but the useful question is what problem frozen literals solve that frozenset(...) does not, beyond a few characters. Immutable defaults would be a real win if they were the... ## Similar posts on daily.dev - [What’s up Python? Wheels in the browser, astral still moves fast, and my new favorite @](https://daily.dev/posts/what-s-up-python-wheels-in-the-browser-astral-still-moves-fast-and-my-new-favorite--9ok4xip7c) · Bite Code · 4 upvotes · 0 comments - [Python Gains frozendict and Other Python News for March 2026 – Real Python](https://daily.dev/posts/python-gains-frozendict-and-other-python-news-for-march-2026-real-python-pllbqmb7u) · Real Python · 11 upvotes · 0 comments --- Tags: [#python](https://daily.dev/tags/python), [#cpython](https://daily.dev/tags/cpython) [View this post on daily.dev](https://daily.dev/posts/what-s-up-python-jsfiddle-for-python-f-objects-and-new-built-ins--sf9j56ctg) ```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":"What’s up Python? 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JSFiddle for Python, f-objects, and new built-ins..."}]} {"@context":"https://schema.org","@type":"WebPage","@id":"https://daily.dev/posts/what-s-up-python-jsfiddle-for-python-f-objects-and-new-built-ins--sf9j56ctg","comment":[{"@type":"Comment","text":"I’d pin the exact Pyodide build in every shared Pystebin link so an old snippet can’t silently change behavior after an upgrade.","datePublished":"2026-09-03T22:07:28.591Z","url":"https://daily.dev/posts/Sf9J56cTg#c-8O6fKLBSm","author":{"@type":"Person","name":"Agustin Barrientos","url":"https://daily.dev/agustinbarrientos","image":"https://media.daily.dev/image/upload/s--5ayxQnqn--/f_auto/v1788281802/avatars/avatar_wQYYVe5Tbj0NJ7C7qPoa8?_a=BAMAMicg0"}},{"@type":"Comment","text":"The uv cache change is the item with the most immediate effect for anyone running ML containers. Deduplicating at file level with blake3 sounds modest until you count how many images pull the same torch wheel over and over - build cache is one of those costs teams never attribute correctly because it hides inside CI minutes rather than showing up as a line item. On PEP 841, the syntax argument will dominate the discussion but the useful question is what problem frozen literals solve that frozenset(…) does not, beyond a few characters. Immutable defaults would be a real win if they were the obvious path rather than an alternative spelling, since the mutable-default footgun survives mainly because doing it right is more typing.","datePublished":"2026-09-07T19:04:41.605Z","url":"https://daily.dev/posts/Sf9J56cTg#c-34aG7deLo","author":{"@type":"Person","name":"Ahmet Özel","url":"https://daily.dev/ahmetozel","image":"https://avatars.githubusercontent.com/u/70992231?v=4"}}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/what-s-up-python-jsfiddle-for-python-f-objects-and-new-built-ins--sf9j56ctg#faq","mainEntity":[{"@type":"Question","name":"How does uv's cache deduplication work and what's the performance impact?","acceptedAnswer":{"@type":"Answer","text":"Uv now deduplicates its cache at the file level by hashing files with the blake3 hash function and storing them in central storage, saving about 10% of total cache size. This costs a 3 to 4% slowdown on cold installs but has no measurable effect on cached installs, and Astral offset the slowdown with an additional optimization shipped alongside it. Track uv's cache and performance changes on daily.dev before they affect your install times."}},{"@type":"Question","name":"What is PEP 841 proposing for Python syntax?","acceptedAnswer":{"@type":"Answer","text":"PEP 841, titled Adding Frozen Syntax to Optimize Immutable Types, proposes built-in syntax for immutable collections, such as f{1, 2, 3} for a frozen set and f{'a': 1} for a frozen dict. Critics note Python lacks a built-in immutable dict until version 3.15, and argue the syntax is confusing alongside f-strings and unnecessary given Python's existing JIT and mutability norms. 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