update build-shell.nix and add gfortran as extra-libraries

this makes `stack build --nix` work without extra system dependencies

build-shell.nix

-{ghc}:
-with (import ./pinned.nix {});
-
-haskell.lib.buildStackProject {
-  inherit ghc;
-  name = "gargantext";
-  buildInputs = [
-    docker-compose
-    blas
+{ ghc
+, pkgs ? import ./pinned.nix {}
+}:
+let
+  buildInputs = with pkgs; [
     bzip2
-    #gfortran
-    gfortran.cc.lib
-    glibc
     gmp
     gsl
     igraph
     liblapack
+    lzma
     pcre
     postgresql
-    #stack
     xz
     zlib
+    blas
+    gfortran7
+    gfortran7.cc.lib
   ];
+
+  libraryPaths = pkgs.lib.makeLibraryPath buildInputs;
+in
+pkgs.haskell.lib.buildStackProject rec {
+  inherit ghc;
+  inherit buildInputs;
+  name = "gargantext";
+
+  shellHook = ''
+    export LD_LIBRARY_PATH="${libraryPaths}"
+    export LIBRARY_PATH="${libraryPaths}"
+  '';
 }

package.yaml

@@ -10,6 +10,8 @@ copyright:
 license: BSD3
 homepage: https://gargantext.org
 ghc-options: -Wall
+extra-libraries:
+- gfortran
 dependencies:
 - extra
 - text

pinned.nix

+# this version of nixpkgs contains liblapack at 3.8.0
+# this version of nixpkgs contains gsl at 2.5.0
 import (
   builtins.fetchTarball {
-    url = "https://github.com/nixos/nixpkgs/archive/ece829033b7b8f4e81261fef5427144df4147bc4.tar.gz";
-    sha256 = "07n91k3d9i9pym8npsszha9mnvg4d1r0l0ldnhk4g8sx15vv1br5";
+    url = "https://github.com/NixOS/nixpkgs/archive/18.09.tar.gz";
+    sha256 = "1ib96has10v5nr6bzf7v8kw7yzww8zanxgw2qi1ll1sbv6kj6zpd";
   }
 )

stack.yaml

@@ -13,7 +13,6 @@ docker:
 
 nix:
   enable: false
-  #packages: [gmp]
   add-gc-roots: true
   shell-file: build-shell.nix