ide-haskell gives an error when importing a package from Prelude.

[milad]

in a .hs file when I write
import Control.Monad.Random

I get the following error:

Could not find module ‘Control.Monad.Random’
Use -v to see a list of the files searched for.

I first submitted this issue here in language-haskell, but then i realized It is thrown by IDE-haskell.

I think it has something to do with ghc-mod, but I don't know exactly how to root it out and solve it. and I wonder how I can know which version of ghc is my ide-haskell is using ?

can you help me solve this?

[Nikolay Yakimov]

Okay, look. I'm maintaining the whole atom-haskell stack, so you can stop switching repos, I just need to understand what's going wrong for you exactly.

Yes, 'could not find module' is ghc-mod error. I have to wonder if you actually have MonadRandom Haskell package installed.

How is your project setup? Do you use cabal, stack, or neither? Have you tried to build your project?

[milad]

My project does not use cabal or stack. It is not a big project and contains only one file. (I am only a beginner).
I have installed my Haskell using a full Haskell platform which includes MonadRandom. I run

ghc-pkg list | grep Monad
MonadRandom-0.4.2.3

which I think means that I have MonadRandom installed
and Also when I run

ghc-pkg describe MonadRandom
...
exposed: True
exposed-modules:
Control.Monad.Random Control.Monad.Random.Class

I think the problem is with ghc-mod. I use

ghc-mod check Risk.hs

I get nothing, which I think that it means the file contains no error. (it is the same file that gives error in atom with ide-haskell).

I used to have an older version of ghc-mod and when I ran ghc-mod check Risk.hs I got the same error as I get in atom (I mean "Could not find module ‘Control.Monad.Random’ ..."). Then I updated the ghc-mod to version 5.6.0 and now I don't get the error in terminal but I get it in atom.

I wish I could provide some useful info.

[Nikolay Yakimov]

I'm terribly sorry, I missed the notification.

So, if you don't get the error in terminal, but you do in Atom, this probably means Atom uses an older version of ghc-mod then.

Try to specify full path to ghc-mod executable in Atom settings. If you're not sure of what path that is exactly, try running which ghc-mod in terminal if on Mac/Linux or where ghc-mod.exe if on Windows.

F.ex.

Hope this helps.

[milad]

This solved my problem. thanks