On Arch linux 'stack install' succeeds while 'stack ghci' doesn't

[PierreR]

I am trying to use stack ghci with language-puppet. stack install works fine but stack ghci gives me a compilation error. For instance:

Puppet/Utils.hs:30:40:
    No instance for (AsNumber Scientific)
      arising from a use of ‘_Integer’

This error makes no sense to me because

• the package does build using stack build
• the lens-aeson version used in the plan does include such instance.

It is important to note that:

• I have been tested the same setting on Ubuntu 14.04.02 LTS Trusty Tahr and stack ghci works fine there.
• I have other (simpler) projects on Arch linux that have no problem with stack ghci.
• After a stack clean, I have another error: Could not find module ‘Paths_language_puppet’. When I stack build again and then stack ghci, I will get back the same compilation error.
• Trying to remove ~/.ghci does not make a difference

One notable difference between the Ubuntu and the Arch linux setup, is the fact that in Ubuntu everything is installed by stack whereas in Arch linux, ghc and many other haskell packages are installed by Arch linux (via pacman)

How to reproduce (on Arch linux):

• git clone https://github.com/bartavelle/language-puppet.git
• stack install (all good)
• stack ghci (compilation error as described).

Using Version 0.1.5.0 X86_64 on Arch linux.

As already discussed in #847, the problem is related to Arch linux. It is suggested in #847 that permissions could be the root cause. I have tested the proposed fix (make file permissions on Arch the same as in Ubuntu) but it did not fix the problem.

[borsboom]

What happens if you use stack --no-system-ghc, so that Stack doesn't use the system-installed GHC/packages?

Also, AFAIK, there's no inherent reason Stack on Arch has to use the system GHC/package. It would only do so if you have already installed GHC/packages separately from Stack (just like on Ubuntu and others). The haskell-stack package at https://aur.archlinux.org/packages/haskell-stack/ does not depend on any system GHC (but will use it if it's there).

[borsboom]

Also, @drwebb, as our resident Arch user, do you have input about why the system-installed GHC/packages would be causing this kind of trouble with stack ghci?

[PierreR]

As a note, I will have to check and see if 0a1a2f7 does not solve the issue.

@borsboom If it does not, I will definitely try stack --no-system-ghc

[PierreR]

I can confirm this issue is solved in 0.1.7.0.

Thanks for the support.

[drwebb]

I've never come across a problem where using the ghc package in the Arch
repos acted like this.

Emanuel Borsboom writes:

Also, @drwebb, as our resident Arch user, do you have input about why the system-installed GHC/packages would be causing this kind of trouble with stack ghci?

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Tristan Webb PhD
Application Engineer
FP Complete