Guess working directory from hs-source-dirs?

[karljs]

I imagine the large majority of projects using Cabal tend to have a single directory under which all their source files are placed, such as $PROJECT_ROOT/src. Given this, doesn't it make sense to try guessing the current directory based on the required cabal property hs-source-dirs when starting a new project?

Apologies if this is a bad suggestion as I'm not familiar with best practices when it comes to packaging Haskell code.

[hvr]

Your suggestion is totally sensible, here's the current state:

• In one place, specifically inferior-haskell-find-project-root, hs-source-dirs is taken into consideration (but it's a very crude heuristic)
• Properly interpreting hs-source-dirs requires to
  • Decide whose build-target's (i.e. library, executable *, benchmark *, test-suite *) hs-source-dirs to take
  • Handling conditional statements which can influence the final value of hs-source-dirs
  • How to handle multiple hs-source-dirs (which for GHCi translate to multiple -i flags)

This is something we definitely need to tackle sooner or later, but right now it seems to me we need an external tool for that (using the Cabal library for parsing & interpreting the current package configuration state).

PS: This issue slightly related to #180

[svenpanne]

I am using haskell-mode 13.7 from http://marmalade-repo.org/packages/haskell-mode, and things almost work: hs-source-dirs is honored, but only at the beginning of a line. The downside is that almost no .cabal file has it there, it is almost always indeted. A quick local fix for the first regexp in haskell-cabal-get-setting (allowing tabs and spaces before the name) works for me, but I don't have a clue if this is the right fix.

It would be nice if this could be fixed, as it is, the current feature is next to useless for lots of packages out there, which is a pity for such a useful thing.

[gracjan]

When using cabal repl the current directory is the directory where *.cabal file resides. Are you talking about some other current directory? Or what?

[gracjan]

In the somewhat related issue #180 it was hinted that cabal repl is the way to go. In general cabal repl is when you have .cabal file and ghci is only when you do not have it. Implementing more logic would be very fragile and user unfriendly.

I'm closing this issue, if I misunderstood something write a comment or reopen.

[svenpanne]

How is cabal repl related to editing Haskell source files?

[gracjan]

@svenpanne: I do not understand your question. Can you elaborate?