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diff --git a/third_party/bazel/rules_haskell/docs/why-bazel.rst b/third_party/bazel/rules_haskell/docs/why-bazel.rst deleted file mode 100644 index 2ad4bc598be3..000000000000 --- a/third_party/bazel/rules_haskell/docs/why-bazel.rst +++ /dev/null @@ -1,102 +0,0 @@ -.. _why-bazel: - -Is Bazel right for me? -====================== - -Nearly as many build tools exist as there are programming languages -out there. C++ has Autotools_/Make_, CMake_ and many others. Java has -Ant_, Maven_, Gradle_ and several more. Haskell has Cabal_, Stack_, -Shake_ and several more. Each of these originated in a given language -community but are in some cases generic enough to support building any -language. Are any of them the right choice for your use case? Should -you be combining several systems? That's what this document should -help you answer. - -Rule of thumb -------------- - -If a combination of the following apply, then you're better off using -Cabal_ or Stack_: - -* your project is an independently publishable single library, or - small set of libraries; -* your project is open source code and has at most small static - assets (hence publishable on Hackage); -* your project is nearly entirely Haskell code with perhaps a little - bit of C; -* your project has many dependencies on other packages found on - Hackage but few if any system dependencies (like zlib, libpng etc); - -Bazel works well for the following use cases: - -* projects that cannot be hosted on Hackage (games with large static - assets, proprietary code etc); -* projects with a very large amount of code hosted in a single - repository; -* projects in which you or your team are writing code in two or more - languages (e.g. Haskell/PureScript, or Haskell/Java, or - Haskell/C++/FORTRAN); - -Rationale ---------- - -For all the benefits it can bring, Bazel also has an upfront cost. -Don't pay that cost if the benefits don't justify it. - -If you don't have much code to build, any build tool will do. Build -issues like lack of complete reproducibility are comparatively easier -to debug, and working around build system bugs by wiping the entire -build cache first is entirely viable in this particular case. So might -as well use low-powered Haskell-native build tools that ship with GHC. -You won't *need* sandboxed build actions to guarantee build system -correctness, completely hermetic builds for good reproducibility, -build caching, test result caching or distributed builds for faster -build and test times. Those features start to matter for larger -projects, and become essential for very large monorepos_. - -Why exactly do these features matter? - -* **Hermetic builds** are builds that do not take any part of the - host's system configuration (set of installed system libraries and - their versions, content of ``/etc``, OS version, etc) as an input. - If all build actions are deterministic, hermeticity guarantees that - builds are reproducible anywhere, anytime. More developers on - a project means more subtly different system configurations to cope - with. The more system configurations, the more likely that the build - will fail in one of these configurations but not in others... Unless - the build is completely hermetic. -* **Sandboxing build actions** guarantees that all inputs to all build - actions are properly declared. This helps prevent build system - correctness bugs, which are surprisingly and exceedingly common in - most non-sandboxing build systems, especially as the build system - becomes more complex. When a build system *might* be incorrect, - users regularly have to wipe the entire build cache to work around - issues. As the codebase becomes very large, rebuilding from scratch - can cost a lot of CPU time. -* **Distributed build caches** make building the code from a fresh - checkout trivially fast. Continuous integration populates the build - cache at every branch push, so that building all artifacts from - fresh checkouts seldom needs to actually build anything at all - locally. In the common case, builds become network-bound instead of - CPU-bound. -* **Distributed build action execution** mean that average build times - can stay constant even as the codebase grows, because you can - seamlessly distribute the build on more machines. -* **Test result caching** is the key to keeping continuous - integration times very low. Only those tests that depend on code - that was modified need be rerun. - -On their own hermetic and sandboxed builds can already save quite -a few headaches. But crucially, without them one can't even hope to -have any of the other features that follow them above. - -.. _Autotools: https://en.wikipedia.org/wiki/GNU_Build_System -.. _Make: https://en.wikipedia.org/wiki/Make_(software) -.. _CMake: https://cmake.org/ -.. _Ant: https://ant.apache.org/ -.. _Maven: https://maven.apache.org/index.html -.. _Gradle: https://gradle.org/ -.. _Cabal: https://www.haskell.org/cabal/ -.. _Stack: http://haskellstack.org/ -.. _Shake: https://shakebuild.com/ -.. _monorepos: https://en.wikipedia.org/wiki/Monorepo |