--- title: Issue 540 | daily.dev description: A weekly roundup of Haskell community news including a deep dive into Bluefin as a capability system, a discussion of orphan instance coherence rules, a look... canonical: https://daily.dev/posts/issue-540-fhwozqquq twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Issue 540 | daily.dev og:description: A weekly roundup of Haskell community news including a deep dive into Bluefin as a capability system, a discussion of orphan instance coherence rules, a look... og:url: https://daily.dev/posts/issue-540-fhwozqquq og:image: https://api.daily.dev/og/posts/fhWOZQQuQ.png og:image:alt: Issue 540 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. # Issue 540 **[Haskell Weekly](https://daily.dev/sources/haskellwkly)** · 5 min read · 0 upvotes · 0 comments ## Summary A weekly roundup of Haskell community news including a deep dive into Bluefin as a capability system, a discussion of orphan instance coherence rules, a look at context complexity for agent APIs, a trick for dependent-if expressions without dependent types, an explainer on the Clash FPGA compiler, a GSoC 2026 wrap-up, an interview about Rust/Haskell influences on Solana's architecture, and the first release of ghcup-gtk. Brief items cover a vulnerability in aeson/text-iso8601 requiring a version bound bump, the Miso 1.13 release, a cabal tooling suggestion, and several community show-and-tell projects including a Template Haskell/Hasql experiment and an experimental Haskell agent harness. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### Is there a security vulnerability in the aeson Haskell library? Yes, a vulnerability affecting aeson and text-iso8601 has been reported, and the recommended fix is to bump the upper bound dependency constraint to less than 2.4 for packages depending on aeson. Developers using aeson should update their cabal or package bounds accordingly to avoid the affected version range. _Track dependency vulnerabilities like this aeson issue by following Haskell ecosystem news on daily.dev._ ## Similar posts on daily.dev - [Issue 522](https://daily.dev/posts/issue-522-3o8bg75xd) · Haskell Weekly · 0 upvotes · 0 comments - [Issue 528](https://daily.dev/posts/issue-528-0qs9djvix) · Haskell Weekly · 0 upvotes · 0 comments - [Issue 538](https://daily.dev/posts/issue-538-sdvfejvbt) · Haskell Weekly · 0 upvotes · 0 comments - [Issue 518](https://daily.dev/posts/issue-518-7hhap2wpm) · Haskell Weekly · 0 upvotes · 0 comments - [Issue 526](https://daily.dev/posts/issue-526-62ezskket) · Haskell Weekly · 0 upvotes · 0 comments --- Tags: [#functional-programming](https://daily.dev/tags/functional-programming), [#haskell](https://daily.dev/tags/haskell) [View this post on daily.dev](https://daily.dev/posts/issue-540-fhwozqquq) ```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":"Issue 540","url":"https://daily.dev/posts/issue-540-fhwozqquq","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/issue-540-fhwozqquq"},"datePublished":"2026-09-03T06:38:54.593Z","dateModified":"2026-09-03T07:29:56.297Z","description":"A weekly roundup of Haskell community news including a deep dive into Bluefin as a capability system, a discussion of orphan instance coherence rules, a look...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/5587ac300cdc202253958d224e471b4b?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/5587ac300cdc202253958d224e471b4b?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Haskell Weekly","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":"Haskell Weekly","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/e30aaf87f5af479cab08b891bb4fcaaa","url":"https://daily.dev/sources/haskellwkly"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/issue-540-fhwozqquq","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"functional-programming,haskell","timeRequired":"PT5M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Haskell Weekly","item":"https://daily.dev/sources/haskellwkly"},{"@type":"ListItem","position":3,"name":"Issue 540"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/issue-540-fhwozqquq#faq","mainEntity":[{"@type":"Question","name":"Is there a security vulnerability in the aeson Haskell library?","acceptedAnswer":{"@type":"Answer","text":"Yes, a vulnerability affecting aeson and text-iso8601 has been reported, and the recommended fix is to bump the upper bound dependency constraint to less than 2.4 for packages depending on aeson. 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