On behalf of the maintainers team I'm happy to announce bytestring-0.11.0.0-rc1: https://github.com/haskell/bytestring/tree/0.11.0.0-rc1 This is a first major release since 2012, so I would like to encourage everyone to give it a try before it is shipped with GHC 9.0. The update focuses on performance improvements and removes several deprecated functions and modules. Changelog: https://github.com/haskell/bytestring/blob/0.11.0.0-rc1/Changelog.md Diff: https://github.com/haskell/bytestring/compare/0.10.12.0...0.11.0.0-rc1 Here is an example of cabal.project: packages: . source-repository-package type: git location: https://github.com/haskell/bytestring tag: 0.11.0.0-rc1 allow-newer: *:bytestring And an example of stack.yaml: resolver: nightly-2020-09-16 packages: - . extra-deps: - github: haskell/bytestring commit: 96c95391025c1ce2240f6dc7bcad06d4191e7793 - github: haskell/cabal commit: 5139d6e72d391bffa3cf06f08884277799eb0b45 subdirs: - Cabal - binary-0.8.8.0 - directory-1.3.6.0 - text-1.2.3.2 - unix-2.7.2.2 - parsec-3.1.14.0 - process-1.6.9.0 allow-newer: true Best regards, Andrew