Intero setup

The following procedure only works when the ghc version of the lts resolver matches the one used for installing Stack.

Setting up a working Intero/Spacemacs environment is not that easy. The following method does not use a .dev/dev-ghc-env file.

Install Stack: Intero requires stack. Install it system wide (in /etc/nixos/local-configuration.nix)

Current used version is 1.6.5 x86_64 as defined by the nixpkgs stable 18.03 channel.

Build with Stack

$HOME/.dev/stack.yaml

resolver: lts-11.17
nix:
  enable: true
  packages:
    - zlib.dev
    - gcc
    - ruby
    - pkgconfig

system-ghc: true
skip-ghc-check: true

Stack downloads all the haskell libs but it seems to do so in a global user space (?) stack clean or removing $PROJECT/.stack-work won’t erase them.

Install intero

Even if you install Intero in user space with stack install intero inside a nix shell (nix-shell -p gcc 'haskellPackages.ghcWithPackages(p: with p; [syb ghc-paths mtl network random])') it would not be recognize within Spacemacs.

This is true with Intero 0.1.32.

The only way seems to let emacs install intero the first time. This will work only if ghc, binutils and gcc are on the $PATH. You will need to add those to local-configuration.nix.

The installation will work but it won’t find intero because it believe it is in x86_64-linux-nix folder that does not exist. The easy fix is to add a symlink: cd $HOME/.stack/compiler-tools; ln -s x86_64-linux x86_64-linux-nix.

With stack version < 1.7 you will need to forcefully enable nix in .stack/config.yaml:

nix:
  enable: true

If you don’t, intero will try to install ghc and it will fail.