我想在Yesod中使用Fay，但无法使Fay的类型检查正常工作。 希望能得到任何建议。
$ stack build
[ 9 of 11] Compiling Handler.Home ( src/Handler/Home.hs, .stack-work/dist/x86_64-linux-dkda49f7ca9b244180d3cfb1987cbc9743/Cabal-2.4.0.1/build/Handler/Home.o )
/home/user/code/myproject/src/Handler/Home.hs:121:13: error:
_ Exception when trying to run compile-time code:
ghc-pkg describe error:
Timestamp 2019-05-07 18:46:44 UTC for /opt/ghc/8.6.5/lib/ghc-8.6.5/package.conf.d/package.cache
ghc-pkg: cannot find package fay-base <- ########### Why?
GHC package manager version 8.6.5
using cache: /opt/ghc/8.6.5/lib/ghc-8.6.5/package.conf.d/package.cache
db stack: ["/opt/ghc/8.6.5/lib/ghc-8.6.5/package.conf.d"]
flag db stack: ["/opt/ghc/8.6.5/lib/ghc-8.6.5/package.conf.d"]
CallStack (from HasCallStack):
error, called at src/Fay/Compiler/Packages.hs:70:24 in fay-0.24.0.3-CdLcUWVJEOpLCiYHkNVTai:Fay.Compiler.Packages
Code: fayFile' (ConE 'StaticR) "HelloWorld"
_ In the untyped splice: $(fayFile' (ConE 'StaticR) "HelloWorld")
|
121 | $( fayFile' (ConE 'StaticR) "HelloWorld" )
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Fay包目前还没有被包含在Stackage中，因此我将它们作为extra-deps添加到了stack.yaml中：
extra-deps: - fay-0.24.0.3
- fay-base-0.21.1.1
- fay-dom-0.5.0.1
- fay-text-0.3.2.2
- yesod-fay-0.10.0
将以下内容添加到dependencies中的package.yaml文件中：
dependencies:
... more dependencies ...
- fay == 0.24.0.3
- fay-base == 0.21.1.1
- fay-dom == 0.5.0.1
- fay-text == 0.3.2.2
- yesod-fay == 0.10.0
Fay 包在本地包数据库中：local package database。
$ stack exec -- ghc-pkg list
/opt/ghc/8.6.5/lib/ghc-8.6.5/package.conf.d
Cabal-2.4.0.1
array-0.5.3.0
base-4.12.0.0
...
/home/user/.stack/snapshots/x86_64-linux-dkda49f7ca9b244180d3cfb1987cbc9743/lts-13.30/8.6.5/pkgdb
Cabal-2.4.1.0
Diff-0.3.4
HUnit-1.6.0.0
...
yesod-1.6.0
yesod-core-1.6.14
yesod-form-1.6.5
yesod-newsfeed-1.6.1.0
yesod-persistent-1.6.0.2
yesod-static-1.6.0.1
/home/user/code/myproject/.stack-work/install/x86_64-linux-dkda49f7ca9b244180d3cfb1987cbc9743/lts-13.30/8.6.5/pkgdb
fay-0.24.0.3
fay-base-0.21.1.1
fay-dom-0.5.0.1
fay-text-0.3.2.2
yesod-fay-0.10.0
然而，试图将HASKELL_PACKAGE_SANDBOX设置为本地数据库，就像Fay故障排除建议的那样并不起作用，因为包含字符串.stack的沙箱在yesod-fay中被忽略。
如果我从yesod-fay中删除此检查，并强制--package-db指向本地数据库，它仍然无法正常工作，并抱怨fay-base找不到fay包。
$ stack build
/home/user/code/myproject/src/Handler/Home.hs:121:13: error:
• Exception when trying to run compile-time code:
Unable to compile Fay module "HelloWorld":
ghc: <command line>: cannot satisfy -package fay-base-0.21.1.1:
fay-base-0.21.1.1-91eIy2f24Wa5OHg9LMre7 is unusable due to missing dependencies:
fay-0.24.0.3-CdLcUWVJEOpLCiYHkNVTai
(use -v for more information)
CallStack (from HasCallStack):
error, called at ./Yesod/Fay.hs:483:3 in yesod-fay-0.10.9999-CzTT9fyZ6636pi0gIof7Ge:Yesod.Fay
Code: fayFile' (ConE 'StaticR) "HelloWorld"
• In the untyped splice: $(fayFile' (ConE 'StaticR) "HelloWorld")
|
121 | $( fayFile' (ConE 'StaticR) "HelloWorld" )
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
更新：如果不使用stack或cabal，而是使用系统范围内已安装的软件包，则不会出现此错误。我猜问题出在我的本地stack软件包数据库（即.stack-work中的那个）。