haskell-mode-hook popup upon return

[developernotes]

Hello,
I recently installed haskell-mode, version 20140309.342 via melpa on Emacs 24.3.50.1 on OS X. I Created the a file, with the following content:

data MyMaybe t = Just t | Nothing

After typing Nothing, I pressed return which triggered my screen to split and showed the help for haskell-mode-hook. It states that the current value is nil. Note that I do not have any customizations to haskell-mode, nor do I have additional haskell emacs packages. Is it correct that this is not the desired behavior?

[ivan-m]

I think you need to choose an indentation mode at least.

[developernotes]

Hi @ivan-m

You are correct, adding (add-hook 'haskell-mode-hook 'turn-on-haskell-simple-indent) resolved the issue. Thanks for the pointer!

[ivan-m]

Maybe we should set a default (probably simple indent) just for cases like this?

[hvr]

@ivan-m iirc there's an issue with circular dependencies between the .el-modules, the customize interface, and the way the indentation is currently integrated in haskell-mode that make it non-trivial to set a default in the current state (or at least would lead to other issues)

[developernotes]

@ivan-m @hvr

Maybe as an alternative, a warning could be issued?

(when (eq nil haskell-mode-hook)
  (message "Please add an indentation hook to haskell-mode-hook"))

[chrisdone]

I did write such a help buffer once that explained the various indentation types, when indentation has not been configured, but maybe it's gone.

[chrisdone]

Oh, wait, the pop-up actually explains all this:

haskell-mode-hook is a variable defined in `haskell-mode.el'.
Its value is (haskell-auto-insert-module-template structured-haskell-mode)

Original value was nil

  This variable may be risky if used as a file-local variable.

Documentation:
Hook run after entering `haskell-mode'.

Some of the supported modules that can be activated via this hook:

   `haskell-decl-scan', Graeme E Moss
     Scans top-level declarations, and places them in a menu.

   `haskell-doc', Hans-Wolfgang Loidl
     Echoes types of functions or syntax of keywords when the cursor is idle.

   `haskell-indentation', Kristof Bastiaensen
     Intelligent semi-automatic indentation Mk2

   `haskell-indent', Guy Lapalme
     Intelligent semi-automatic indentation.

   `haskell-simple-indent', Graeme E Moss and Heribert Schuetz
     Simple indentation.

Module X is activated using the command `turn-on-X'.  For example,
`haskell-doc' is activated using `turn-on-haskell-doc'.
For more information on a specific module, see the help for its `X-mode'
function.  Some modules can be deactivated using `turn-off-X'.

See Info node `(haskell-mode)haskell-mode-hook' for more details.

Warning: do not enable more than one of the three indentation
modes. See Info node `(haskell-mode)indentation' for more
details.

You can customize this variable.

[back]

[chrisdone]

Probably what's missing is a simple line that says how to add such a hook.

[developernotes]

Hi @chrisdone

If it provided what you are showing above in the popup that would be great, unfortunately, this is what is displayed out of the box from the melpa installation:

haskell-mode-hook is a variable defined in `haskell-mode.el'.
Its value is nil

This variable may be risky if used as a file-local variable.

Documentation:
Hook run after entering Haskell mode.
No problems result if this variable is not bound.
`add-hook' automatically binds it.  (This is true for all hook variables.)

You can customize this variable.

Maybe something is out of sync between your version and what is available on melpa?

[hvr]

@developernotes what does M-x haskell-version tell?

(also, does your current haskell-mode version have any pointers into the info manual at all?)

[developernotes]

Hi @hvr
M-x haskell-version prints this for me:

haskell-mode version @VERSION@ (@GIT_VERSION@ @ /Users/nparker/.emacs.d/elpa/haskell-mode-20140309.342/)

The info docs are installed, so section 6 on indentation is visible when viewed.

This issue got me as well. Would have been really nice if after reading that lengthy intro I had any idea how to fix it. Instead I spent 15 minutes thinking I was crazy and almost disabled haskel-mode / renamed my file something other than .hs before stumbling on this page in my 3rd google search. This should really be modifed somehow.
My haskell-version is:
haskell-mode version @Version@ (@GIT_VERSION@ @ /home/russell/.emacs.d/elpa/haskell-mode-20140430.945/)
installed through list-packages and selecting haskell-mode.

For me the issue persists after adding 'structured-haskell-mode to 'haskell-mode-hook. It should not happen because then 'haskell-mode-hook is not nil.

[developernotes]

Hi @sumitsahrawat

Do you get the same behavior if you explicitly include a (require 'shm)?