modules: add haskell module

2 files changed, 71 insertions, 0 deletions

diff --git a/modules/default.nix b/modules/default.nix
index 59b128c..ef71bd5 100644
--- a/modules/default.nix
+++ b/modules/default.nix
@@ -6,6 +6,7 @@ in {
   imports = [
     ./coq.nix
     ./golang.nix
+    ./haskell.nix
     ./latex.nix
     ./nix.nix
     ./ocaml.nix
diff --git a/modules/haskell.nix b/modules/haskell.nix
new file mode 100644
index 0000000..1b8bc45
--- /dev/null
+++ b/modules/haskell.nix
@@ -0,0 +1,70 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+with builtins;
+let
+  cfg = config.haskell;
+
+  spacemacsPackages = haskellPackages:
+    with haskellPackages; [
+      apply-refact
+      hlint
+      stylish-haskell
+      hasktags
+    ];
+  haskellBuildInput = (if cfg.hoogle.enable then
+    cfg.haskellPackages.ghcWithHoogle
+  else
+    cfg.haskellPackages.ghcWithPackages) (haskellPackages:
+      (cfg.packages haskellPackages)
+      ++ optionals cfg.spacemacs.enable (spacemacsPackages haskellPackages)
+      ++ optional cfg.cabal.enable pkgs.cabal-install);
+in {
+  options.haskell = {
+    enable = mkEnableOption { name = "haskell"; };
+    haskellPackages = mkOption {
+      type = with types;
+        addCheck (lazyAttrsOf anything)
+        (packages: lib.hasAttr "ghcWithPackages" packages);
+      default = pkgs.haskellPackages;
+      defaultText = literalExample "pkgs.haskellPackages";
+      description = ''
+        The set of Haskell packages from which to get GHC and its packages.
+        Use this option to set the version of GHC.
+      '';
+      example = literalExample "pkgs.haskell.packages.ghcjs";
+    };
+    packages = mkOption {
+      type = with types; functionTo (listOf package);
+      default = _: [ ];
+      defaultText = literalExample "_ : []";
+      description = ''
+        Haskell packages that will be made available to the environment.
+      '';
+      example = literalExample ''
+        haskellPackages: with haskellPackages; [ async cabal-install ];
+      '';
+    };
+    # Whether to load packages required by Spacemacs layer.
+    spacemacs.enable = mkEnableOption "spacemacs";
+
+    hoogle.enable = mkEnableOption "hoogle";
+
+    cabal = {
+      enable = mkEnableOption "cabal";
+      package = mkOption {
+        type = types.package;
+        default = pkgs.cabal-install;
+        defaultText = defaultText "pkgs.cabal-install";
+        description = "The package for cabal.";
+      };
+      # TODO: add ability to set path to binaries
+      # TODO: explain that here cabal is not loaded with ghc, but as an external package
+    };
+  };
+
+  config = mkIf cfg.enable {
+    buildInputs = [ haskellBuildInput ];
+    envVars.PATH.value = mkIf cfg.cabal.enable "~/.cabal/bin"; # only on linux
+  };
+}