[Haskell] ghc-mod: No such file or directory

[zsparal]

After enabling contrib/lang/haskell it refuses to acknowledge that I have ghc-mod installed. ~/.cabal/bin is added to PATH:

$ env | grep PATH
PATH=/home/gustorn/.cabal/bin:/home/gustorn/.local/bin: [rest of PATH]

My .spacemacs file (.el extension added for syntax highlighting): .spacemacs (I already tried with flyspell not excluded)

The actual error:

Initializing...
"ghc-mod" not found
File mode specification error: (file-error "Searching for program" "no such file or directory" "ghc-mod")
Spacemacs is up to date.

:company-ghc-diagnose

* company-ghc backend found: company-ghc
* automatic scan module is enabled
* ghc-boot process has not been done

Module                                  Alias               Candidates
-------------------------------------------------------------------------------
Prelude   

Using :!ghc-mod inside emacs finds the executable just fine.

OS: Linux
Emacs: GNU Emacs 24.5.1

[codygman]

What does which ghc-mod give you inside of an eshell?

[zsparal]

It doesn't find it:

which: no ghc-mod in (/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/share/java/gradle/bin:/usr/lib/jvm/default/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl)

So I'm guessing this line: (add-to-list 'exec-path "~/.cabal/bin/") is either at the wrong place or is just plain wrong. I'm fairly new to emacs, so I apologize if the solution is really obvious for more experienced people.

[syl20bnr]

You can inspect the value of the variable with SPC h d exec-path RET.

[tuhdo]

It should be SPC h d v exec-path RET.

[zsparal]

Alright, I solved the problem: exec-path was not picked up from the dotspacemacs/init function; adding the same line to dotspacemacs/config solved the problem, which means either something isn't quite working right in spacemacs, or if this is the intended behaviour, then the Haskell layer readme should be updated (or it's completely possible that the error is on my end, even though this is a completely fresh install).

[syl20bnr]

dotspacemacs/init is exectued before the initialization of the layers. Possibly somewhere in the layers exec-path is overwritten (could be also in a package but it less likely).
dotspacemacs/config is executed after the initialization of the layers.

[zsparal]

I get that, but here's a quote from the Haskell layer readme:

"or [add this path] to the Emacs exec-path variable in the dotspacemacs/init function of your .spacemacs file:"

This doesn't work, while adding it to dotspacemacs/config works just fine.

[luhkevin]

Gustorn -- thank you for this fix! But not for the Haskell layer. I was setting up gtags as per the instructions here: https://github.com/syl20bnr/spacemacs/tree/master/contrib/gtags

When I tried to use helm-gtags, or invoke any of the installed programs such as gtags or global, spacemacs would say that there was "no such file or directory"

So I added "/usr/bin" -- where global is installed -- to the "exec-path" and helm-gtags worked.

I looked at the path with SPC h d v exec-path RET., and it is definitely not the same as the PATH variable in my shell....in fact it only includes:
("/usr/bin" "%s/" "/usr/lib/emacs/24.5/x86_64-unknown-linux-gnu/")

Is this supposed to happen? Or is spacemacs doing something funny?