HIE works

.gitignore

@@ -0,0 +1,3 @@
+!.vscode/
+
+**/dist-newstyle/

.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+    "nixEnvSelector.nixShellConfig": "${workspaceRoot}/shell.nix"
+}

README.md

@@ -68,9 +68,13 @@ Repeat from step (2) when you add, remove or modify a `.cabal` file.
 
 ### Configuration
 
-It is advised to edit only the following specified files (except if you know what you are doing).
+Some parameters can be configured by editing the file `./nix/confgi.nix`. 
 
-* The most basic parameters are in `./nix/config.nix`.
+For now you can:
+* Change the GHC version to use
+    * Warning: check that this version is supported by nixpkgs and your IDE
+* Select the IDE used
+    * For now either ghcide (default) or HIE
 
 ## Motivations
 

nix/config.nix

@@ -2,7 +2,6 @@
   # GHC version
   ghc-version = "ghc865";
 
-  # IDEs
-  use-ghcide = true;
-  use-hie = false;
+  # IDEs (either "ghcide" or "hie")
+  ide = "ghcide";
 }

nix/hie.nix

@@ -1,9 +1,10 @@
 # selector:
 #   * Function to select HIE ghc versions. See here https://github.com/Infinisil/all-hies#declarative-installation-nixos-home-manager-or-similar
 #   * Example: p: { inherit (p) ghc865; }
-{ selector }:
+{ ghc-version }:
 let
   # HIE from all-hies (use Cachix !)
-  all-hies = import (fetchTarball "https://github.com/infinisil/all-hies/tarball/master") {};
+  all-hies-rev = "master";
+  all-hies = import (fetchTarball "https://github.com/infinisil/all-hies/tarball/${all-hies-rev}") {};
 in
-  all-hies.selection { inherit selector; }
+  all-hies.selection { selector = p: { "${ghc-version}" = builtins.getAttr ghc-version p; }; }

nix/nixpkgs.nix

@@ -1,15 +1,15 @@
+{ usePinnedNixpkgs ? false }:
 # The version of nixpkgs used for this project
 let
   # Either a pinned version
-  get-pinned-nixpkgs = rev: 
+  get-pinned-nixpkgs = ref: rev:
     builtins.fetchGit {
         url = "https://github.com/NixOS/nixpkgs.git";
-        ref = "master";
-        inherit rev;
+        inherit ref rev;
     };
-  # pinned-nixpkgs = get-pinned-nixpkgs "cca0c894a13ec398de8b046174239513197f5c74"
+  pinned-nixpkgs = get-pinned-nixpkgs "master" "cca0c894a13ec398de8b046174239513197f5c74" {};
 
   # Or the current local
-  current-local = import <nixpkgs>;
+  current-local = import <nixpkgs> {};
 in
-  current-local
+  if usePinnedNixpkgs then pinned-nixpkgs else current-local

shell.nix

@@ -7,9 +7,12 @@ let
   ghc-selector = p: pkgs.lib.attrsets.getAttr ghc-version p;
 
   # IDEs to chose from
-  inherit (config) use-ghcide use-hie;
+  inherit (config) ide;
+  use-ghcide = ide == "ghcide";
+  use-hie = ide == "hie";
+
   ghcide = pkgs.lib.attrsets.getAttr ("ghcide-" + ghc-version) (import ./nix/ghcide.nix);
-  hie = import ./nix/hie.nix { selector = ghc-selector; };
+  hie = import ./nix/hie.nix { inherit ghc-version; };
 
   # Haskell package set with ghcWithPackages changed to always add Hoogle
   haskellPackages = ghc-selector pkgs.haskell.packages;