如果你有一个最近版本的 cabal-install （> = 0.10，我想），你可以尝试做

If you have a recent-ish version of cabal-install (>= 0.10, I think), you can try doing

$ cabal install --reinstall --upgrade-dependencies world

不幸的是，它在我的情况下不起作用：

Unfortunately, it didn't work in my case:

$ cabal install --dry-run --reinstall world
Resolving dependencies...
cabal: cannot configure Agda-2.2.10. It requires haskell-src-exts >=1.9.6 &&
<1.10
For the dependency on haskell-src-exts >=1.9.6 && <1.10 there are these
packages: haskell-src-exts-1.9.6. However none of them are available.
haskell-src-exts-1.9.6 was excluded because haskell-src-exts-1.11.1 was
selected instead
haskell-src-exts-1.9.6 was excluded because hlint-1.8.12 requires
haskell-src-exts ==1.11.*

如果你碰撞变成这样的错误，您可以尝试手动编辑〜/ .cabal / world 文件。

If you bump into an error like this, you can try manually editing the ~/.cabal/world file.