Haskell-mode not respecting cabal sandboxes

[dmjio]

After cabal-installing my project inside of a cabal sandbox (1.18.0.3) I am able to open a cabal repl and inspect the packages. When I open up emacs w/ haskell-mode and C-c C-l to send to ghci I get :

Prelude> :cd /Users/dmj/Project/
Prelude> :load "Main.hs"

ST/Common/Types.hs:37:18:
    Could not find module `Web.Stripe.Customer'
    Use -v to see a list of the files searched for.
Failed, modules loaded: none.
Prelude>

How do I get haskell-mode to respect cabal sandboxes?

[Eilie]

Having this issue too. Fix needed.

[dmjio]

@Eilie change your repl to cabal repl in your haskell-mode config and it will respect your sandbox

[dmjio]

You can do it if you go M - x apropos and type haskell-mode and look for inferior haskell mode then change ghci to cabal repl. Note this means that you will always need a cabal sandbox when loading a project.

[Eilie]

It doesn't help. I've changed ghci to cabal repl and after loading file within cabal sandbox I'm getting "cannot find module" errors for all external dependencies file having like "Data.Aeson".

[dmjio]

@ellie, I stopped doing it the way I was previous (shown above). Use the following in your .emacs to rebind.

;; rebind inferior mode to interactive mode
(eval-after-load "haskell-mode"
  '(progn
     (define-key haskell-mode-map (kbd "C-c C-l") 'haskell-process-load-or-reload)
     (define-key haskell-mode-map (kbd "C-`") 'haskell-interactive-bring)
     (define-key haskell-mode-map (kbd "C-c C-t") 'haskell-process-do-type)
     (define-key haskell-mode-map (kbd "C-c C-i") 'haskell-process-do-info)
     (define-key haskell-mode-map (kbd "C-c C-c") 'haskell-process-cabal-build)
     (define-key haskell-mode-map (kbd "C-c C-k") 'haskell-interactive-mode-clear)
     (define-key haskell-mode-map (kbd "C-c c") 'haskell-process-cabal)
     (define-key haskell-mode-map (kbd "SPC") 'haskell-mode-contextual-space)))

;; custom haskell-mode settings
(custom-set-variables
 '(haskell-process-log t)
 '(haskell-process-type (quote cabal-repl)) ;; mui importante
 '(inferior-haskell-wait-and-jump t))

[Eilie]

@dmijo Thank you! That works fine for library(code inside "library" section of cabal file) but for executables(I have couple of executable with different main files) it fails when executable having additional build-depends. Haskell-mode suggests to add these dependencies from executable to library but that's not quite right since library doesn't actually depends on what executable depends if that makes sense.

[dmjio]

yea, you might have to manually intervene in some cases. Or just split the executables into their own projects.

[hvr]

@dmjio you might wanna point out that by doing that, you change to the totally different haskell-interactive-mode. This issue was about the older so-called inferior-haskell-mode which has different trade-offs.

[dmjio]

@hvr, good point. I believe inferior-haskell-mode is deprecated, at least, not in active dev. compared to haskell-interactive-mode.

[ivan-m]

You can switch to different item in the .cabal file with haskell-session-change-target, but it's a little clumsy to use (ideally it would give you an ido list of possible completions).

You also need to remember to do a cabal configure && cabal install --only-dependencies when using sandboxes before trying to load a file with cabal repl.

[Eilie]

@ivan-m,

Thanks for pointing haskell-session-change-target out.

[gracjan]

@dmjio: Do you consider this fixed for your case? Can we close this issue or should there be a follow up pull request?

[DanielAtSamraksh]

To change the haskell-program-name variable, do:
C-h v haskell-program-name RET

Change 'ghci' to 'cabal repl'. Click the 'Apply and Save' button.

[DanielAtSamraksh]

To change haskell-program-name from 'ghci' to 'cabal repl':

C-h v haskell-program-name RET

Click 'customize'.
Change 'ghci' to 'cabal repl'.
Click 'Apply and Save'.

[gracjan]

Haskell-process-type is more relevant.