stack build in an empty directory downloads a new package cache

[chreekat]

b@fuzzbomb ~/tmp/foo $ stack build
PackageNoCabalFileFound "/home/b/tmp/foo/"
Writing default config file to: /home/b/tmp/foo/stack.yaml
Downloading build plan from: https://raw.githubusercontent.com/fpco/lts-haskell/master/lts-2.13.yaml

That seems like extra work for a failure condition.

[snoyberg]

Well, it's not exactly a failure condition. There are legitimate use cases here, e.g.:

$ stack build
$ stack deps vector
$ stack ghci

So it seems at least somewhat reasonable for it to behave this way IMO.

[chrisdone]

Perhaps an improvement to this behaviour would be explaining its intentions. I.e. "I don't have anything to do and I didn't find a cabal file, so I'm going to assume you want a configuration."

[chreekat]

What is stack build being used for in that case?

How does that mesh with #59, and the idea that "It also caters to newbies reading books who just want to run ghc on a file. You can run stack ghc X.hs and it will download GHC if necessary, etc...". Would a yaml be created in the latter scenario? It would be nice if it wasn't necessary, since it is likely X.hs will be in a home directory, or in a directory full of other one-off test files.

[snoyberg]

Fair point, maybe we should just change behavior to exiting if there's no .cabal file present. We already have plans to improve stack ghci and friends so that they can run without a stack.yaml file, so perhaps this all adds up nicely.

[chreekat]

@chrisdone, or: "I don't have anything to do. Shall I run stack init for you?"

[chrisdone]

Fair points, indeed. I'm not really sure on this one. Going to think about it.

[snoyberg]

Discussed with @chrisdone, we'll just exit stack.yaml construction if no .cabal file exists, and leave the rest of init to #253.

[snoyberg]

OK, this is implemented, with the real solution to be handled via #253. Closing.