我有很多问题cabal-install：
1：每次我做cabal update，它告诉我做cabal install cabal-install，所以我做，然后当我cabal update再次做时，它说同样的话。
2：当我尝试ghc-mod从hackage安装时，它给了我这个错误：
[username@arch ~]$ cabal install ghc-mod
In order, the following will be installed:
haskell-src-exts-1.14.0 (reinstall) changes: pretty-1.1.1.1 -> 1.1.1.0
hlint-1.8.55 (reinstall)
ghc-mod-3.1.4
setup: The program happy version >=1.17 is required but it could not be found.
ghc-mod-3.1.4 depends on haskell-src-exts-1.14.0 which failed to install.
haskell-src-exts-1.14.0 failed during the configure step.
hlint-1.8.55 depends on haskell-src-exts-1.14.0 which failed to install.
所以问题是The program happy version >=1.17 is required but it could not be found.，所以我安装happy 1.19.2使用cabal install happy没有问题。
我又试cabal install ghc-mod了一次，同样的错误，所以我试了cabal install haskell-src-exts --reinstall --force-reinstalls。它给了我以下错误：
[username@arch ~]$ cabal install haskell-src-exts --reinstall --force-reinstalls
Configuring haskell-src-exts-1.14.0...
setup: The program happy version >=1.17 is required but it could not be found.
Failed to install haskell-src-exts-1.14.0
cabal: Error: some packages failed to install:
haskell-src-exts-1.14.0 failed during the configure step. The exception was:
ExitFailure 1
基本上The program happy version >=1.17 is required but it could not be found.。这么开心又出问题了？
我还尝试从hackage下载tar.gz文件并cabal install在
.cabal文件上使用，还修改了.cabal文件以忽略依赖项，仍然失败。