35 lines
1.3 KiB
Nix
35 lines
1.3 KiB
Nix
# Demonstration of incremental builds for Haskell. Useful for speeding up CI.
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#
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# See: https://www.haskellforall.com/2022/12/nixpkgs-support-for-incremental-haskell.html
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# See: https://felixspringer.xyz/homepage/blog/incrementalHaskellBuildsWithNix
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{ haskell, lib }:
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let
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inherit (haskell.lib.compose) overrideCabal;
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# Incremental builds work with GHC >=9.4.
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temporary = haskell.packages.ghc944.temporary;
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# This will do a full build of `temporary`, while writing the intermediate build products
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# (compiled modules, etc.) to the `intermediates` output.
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temporary-full-build-with-incremental-output = overrideCabal (drv: {
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doInstallIntermediates = true;
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enableSeparateIntermediatesOutput = true;
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}) temporary;
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# This will do an incremental build of `temporary` by copying the previously
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# compiled modules and intermediate build products into the source tree
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# before running the build.
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#
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# GHC will then naturally pick up and reuse these products, making this build
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# complete much more quickly than the previous one.
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temporary-incremental-build = overrideCabal (drv: {
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previousIntermediates = temporary-full-build-with-incremental-output.intermediates;
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}) temporary;
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in
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temporary-incremental-build.overrideAttrs (old: {
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meta = {
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maintainers = lib.teams.mercury.members;
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};
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})
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