diff --git a/pkgs/test/haskell/default.nix b/pkgs/test/haskell/default.nix index 337d2811c655..86764380ecc3 100644 --- a/pkgs/test/haskell/default.nix +++ b/pkgs/test/haskell/default.nix @@ -6,4 +6,5 @@ lib.recurseIntoAttrs { documentationTarball = callPackage ./documentationTarball { }; setBuildTarget = callPackage ./setBuildTarget { }; writers = callPackage ./writers { }; + incremental = callPackage ./incremental { }; } diff --git a/pkgs/test/haskell/incremental/default.nix b/pkgs/test/haskell/incremental/default.nix new file mode 100644 index 000000000000..b94a85277db3 --- /dev/null +++ b/pkgs/test/haskell/incremental/default.nix @@ -0,0 +1,35 @@ +# Demonstration of incremental builds for Haskell. Useful for speeding up CI. +# +# See: https://www.haskellforall.com/2022/12/nixpkgs-support-for-incremental-haskell.html +# See: https://felixspringer.xyz/homepage/blog/incrementalHaskellBuildsWithNix + +{ haskell, lib }: + +let + inherit (haskell.lib.compose) overrideCabal; + + # Incremental builds work with GHC >=9.4. + turtle = haskell.packages.ghc944.turtle; + + # This will do a full build of `turtle`, while writing the intermediate build products + # (compiled modules, etc.) to the `intermediates` output. + turtle-full-build-with-incremental-output = overrideCabal (drv: { + doInstallIntermediates = true; + enableSeparateIntermediatesOutput = true; + }) turtle; + + # This will do an incremental build of `turtle` by copying the previously + # compiled modules and intermediate build products into the source tree + # before running the build. + # + # GHC will then naturally pick up and reuse these products, making this build + # complete much more quickly than the previous one. + turtle-incremental-build = overrideCabal (drv: { + previousIntermediates = turtle-full-build-with-incremental-output.intermediates; + }) turtle; +in + turtle-incremental-build.overrideAttrs (old: { + meta = { + maintainers = lib.teams.mercury.members; + }; + })