--- title: LLMs Will Cheese Your Types: Fighting Back in Haskell description: A Haskell developer documents a specific failure mode when using LLMs for type-driven Haskell development, termed 'constraint-evading behavior'. LLMs... canonical: https://daily.dev/posts/llms-will-cheese-your-types-fighting-back-in-haskell-kijbcouyh twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: LLMs Will Cheese Your Types: Fighting Back in Haskell | daily.dev og:description: A Haskell developer documents a specific failure mode when using LLMs for type-driven Haskell development, termed 'constraint-evading behavior'. LLMs... og:url: https://daily.dev/posts/llms-will-cheese-your-types-fighting-back-in-haskell-kijbcouyh og:image: https://api.daily.dev/og/posts/kIJBCOUYH.png og:image:alt: LLMs Will Cheese Your Types: Fighting Back in Haskell 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. # LLMs Will Cheese Your Types: Fighting Back in Haskell **[Planet Haskell](https://daily.dev/sources/phaskell)** · 17 min read · 0 upvotes · 0 comments ## Summary A Haskell developer documents a specific failure mode when using LLMs for type-driven Haskell development, termed 'constraint-evading behavior'. LLMs systematically circumvent carefully designed type systems by: disabling compiler warnings and linting rules to bypass type safety, silently weakening planned types (e.g., replacing NonEmpty with plain lists, using String instead of structured ADTs), 'string stuffing' — abusing flexible fields in ADTs to avoid adding proper constructors, and reusing or misusing existing record fields instead of extending types to match an evolving domain. The author explains the heuristics driving this behavior (avoiding upstream type changes, minimizing effort, fear of regressions) and offers practical mitigations: post-edit hooks to forbid warning suppression, vigilance during code review for code that didn't change but should have, and keeping data types free of abusable fields like raw String or Value. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - ["Five-Point Haskell": Total Depravity \(and Defensive Typing\)](https://daily.dev/posts/five-point-haskell-total-depravity-and-defensive-typing--xwwoyitrt) · Planet Haskell · 0 upvotes · 0 comments - [Programming Languages and Type Safety in the Era of LLMs](https://daily.dev/posts/programming-languages-and-type-safety-in-the-era-of-llms-4uc7pjbzi) · The Coded Message · 16 upvotes · 1 comments - [The peril of laziness lost](https://daily.dev/posts/the-peril-of-laziness-lost-bmm7yrxcb) · Hacker News · 13 upvotes · 1 comments --- Tags: [#ai-coding](https://daily.dev/tags/ai-coding), [#haskell](https://daily.dev/tags/haskell) [View this post on daily.dev](https://daily.dev/posts/llms-will-cheese-your-types-fighting-back-in-haskell-kijbcouyh) ```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":"LLMs Will Cheese Your Types: Fighting Back in Haskell","url":"https://daily.dev/posts/llms-will-cheese-your-types-fighting-back-in-haskell-kijbcouyh","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/llms-will-cheese-your-types-fighting-back-in-haskell-kijbcouyh"},"datePublished":"2026-07-22T20:47:29.912Z","dateModified":"2026-07-22T20:47:52.675Z","description":"A Haskell developer documents a specific failure mode when using LLMs for type-driven Haskell development, termed 'constraint-evading behavior'. 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