haskell
Using ~ in `remote-repo-cache` crashes `cabal update` and isn't recognised by `cabal build`
Describe the bug
Having a cabal.project file with remote-repo-cache: ~/.cache/cabal/my-packages breaks cabal update, with the following error:
cabal update
Downloading the latest package list from hackage.haskell.org
~/.cache/cabal/my-packages/hackage.haskell.org/01-index.timestamp: withFile: does not exist (No such file or directory)
specifying as /home/jamie/.cache/cabal/my-packages works just fine with cabal update. Having done this, switching back to ~/ instead of /home/jamie/ produces the following for cabal build:
Error: [Cabal-7160]
The package list for 'hackage.haskell.org' does not exist. Run 'cabal update' to download it.
This seems to affect cabal versions from at least as far back as 3.10.1.0, I also tested with 3.10.3.0 and 3.12.1.0 with the same issue.
~ is a shell-ism, and programs have to do extra work to support it. At which point the question becomes whether to also support other shell-isms (~user, $envar, etc.). Most programs punt on it, aside from e.g. editors and such.
In which case, there needs to be some way of specifying the home directory in the configuration here! But presumably, whatever is doing the file I/O code-side should just be using native APIs that do understand ~, no? I'm pretty sure I can use ~ in regular file I/O right (if not I certainly can in other languages!)
Some languages support it (e.g. Perl), others do not (e.g. C/C++, Java). There is no native API that supports it, except in convenience-oriented languages that specifically support shell-isms. (Try something like cat ~/foo vs. cat '~/foo'.)
That's true, but in Java, say, you can use System.getProperty("user.home") to fetch it, perhaps if cabal is running in a UNIX environment it can take a leading ~ on a path and lookup the appropriate home?
Hi, my workflow would be improved a lot if I could commit my user-wide cabal config to my dotfiles. However that is not something I want right now as I might have different home folder names on different machines.
