haskell - 摇一摇: how do I depend on dynamically generated source files?

Question

给定这样的目录结构:

.
├── frontend
│   ├── _build/          -- build dir, all files produced by shake, except for Frontend.elm, go here
│   ├── Build.hs         -- the build script
│   ├── build.sh         -- wrap Build.hs with `stack exec build -- $@`
│   ├── other files ...
│   ├── Frontend.elm     -- generated by a rule in Build.hs, `protoc  -I../proto --elm_out=. ../proto/frontend.proto`
│   ├── Index.elm        -- hand written source file
│   └── other elms ...   -- hand written source files
└── proto
    └── frontend.proto   -- protocol buffer message defination, hand written

目标_build/index.js依赖于所有.elm文件，包括Frontend.elm，但是 Frontend.elm 是由 Build.hs 中的规则生成的，如果我盲目这样做:

want ["_build/index.js"]
"_build/index.js" %> \out -> do
    elms <- filter (not . elmStuff)
            <$> (liftIO $ getDirectoryFilesIO "" ["//*.elm"])
    need elms
    blah blah

want ["Frontend.elm"]
"Frontend.elm" %> \_out -> do
    cmd ["protoc", "blah", "blah"]

build.sh clean 会给我:

Lint checking error - value has changed since being depended upon:
  Key:  Frontend.elm
  Old:  File {mod=0x608CAAF7,size=0x53D,digest=NEQ}
  New:  File {mod=0x608CAB5B,size=0x53D,digest=NEQ}

有没有办法告诉 shake 留意动态生成的 Frontend.elm，也许先构建它，这样它在构建的其余部分就不会改变，我尝试过 优先级 100 ("Frontend.elm"%> ...)，不起作用。

Answer 1

你可能应该:

1. 切换自 getDirectoryFilesIO ，它不跟踪文件系统的更改，为 getDirectoryFiles ，确实如此。
2. 声明您对 Frontend.elm 的依赖，即使文件系统中尚不存在，您也知道您需要它(因此 getDirectoryFiles 可能看不到它)。
3. (可选)请勿打扰 want ing Frontend.elm ，因为您只想将其作为黑客来启用 _build/index.js .

经过这些更改，它看起来像这样:

want ["_build/index.js"]
"_build/index.js" %> \out -> do
    need ["Frontend.elm"]
    elms <- filter (not . elmStuff)
            <$> getDirectoryFiles "" ["//*.elm"]
    need elms
    blah blah

"Frontend.elm" %> \_out -> do
    cmd ["protoc", "blah", "blah"]

警告讲师:我还没有测试过这个解决方案。