{"slug": "rfc-yamlet-a-yaml-1-2-library", "title": "[RFC] yamlet: a YAML 1.2 library", "summary": "Developer arybczak released an RFC for yamlet, a YAML 1.2 library for Haskell offering fast encoding and decoding, structure preservation including comments, and generic deriving that compiles to efficient code for common data type shapes. The library was stress-tested against Claude Opus 5.5 and used to build haskell-gha without workarounds, with the author soliciting API feedback before the first release. Documentation is largely Claude-generated with doctests included.", "body_md": "I’ve been stress-testing Claude Opus 5.5 and thought a YAML library with a good API would fill a hole in the ecosystem. The result:\n\nIn short, yamlet is a YAML 1.2 library with fast encoding/decoding, preservation of structure (including comments where you want them) and support for generic deriving that compiles to good code for common shapes of data types.\n\nIf anyone was doing YAML processing in Haskell and found it lacking, have a look at the API. It was good enough for me to make [haskell-gha](https://github.com/arybczak/haskell-gha) without any workarounds, but if I missed something, I’d like to know before the first release.\n\nDocumentation is mostly Claude-generated, so expect an odd wording here and there, but there’s also plenty of doctests.", "url": "https://wpnews.pro/news/rfc-yamlet-a-yaml-1-2-library", "canonical_source": "https://discourse.haskell.org/t/rfc-yamlet-a-yaml-1-2-library/14795#post_1", "published_at": "2026-10-04 07:16:36+00:00", "updated_at": "2026-10-04 07:42:45.250497+00:00", "lang": "en", "topics": ["developer-tools"], "entities": ["yamlet", "Haskell", "Claude Opus 5.5", "haskell-gha", "arybczak"], "also_reported_by": [], "alternates": {"html": "https://wpnews.pro/news/rfc-yamlet-a-yaml-1-2-library", "markdown": "https://wpnews.pro/news/rfc-yamlet-a-yaml-1-2-library.md", "text": "https://wpnews.pro/news/rfc-yamlet-a-yaml-1-2-library.txt", "jsonld": "https://wpnews.pro/news/rfc-yamlet-a-yaml-1-2-library.jsonld"}}