Added nix expression for Hydra

Author: sebright

release.nix

@@ -0,0 +1,38 @@
+let
+  inherit (builtins) listToAttrs;
+  inherit (pkgs.lib) nameValuePair;
+  pkgs = import <nixpkgs> {};
+  extraPkgs = import <haskellPackages>;
+  combos = [
+    { ghcV = "704"; aesonV = "0_6_0_0"; }
+    { ghcV = "742"; aesonV = "0_7_0_4"; }
+    { ghcV = "763"; aesonV = "0_7_0_4"; }
+    { ghcV = "783"; aesonV = "0_8_0_2"; }
+    # { ghcV = "HEAD"; aesonV = "0_8_0_2"; }
+  ];
+  toLabel = { ghcV, aesonV }: "ghc${ghcV}-aeson_${aesonV}";
+  build = { ghcV, aesonV }:
+    let
+      hp = pkgs.lib.getAttrFromPath ["haskellPackages_ghc${ghcV}"] pkgs;
+      aeson = hp.callPackage (pkgs.lib.getAttrFromPath ["aeson_${aesonV}"] extraPkgs) {};
+      inherit (hp) cabal HUnit mtl testFramework testFrameworkHunit text unorderedContainers vector;
+    in cabal.mkDerivation (self: {
+      pname = "json-rpc-server";
+      version = "0.1.3.0";
+      isLibrary = true;
+      src = <jsonRpcServerSrc>;
+      buildDepends = [ aeson mtl text unorderedContainers vector ];
+      testDepends = [
+        aeson HUnit mtl testFramework testFrameworkHunit text
+        unorderedContainers vector
+      ];
+      meta = {
+        description = "JSON RPC 2.0 on the server side.";
+        license = self.stdenv.lib.licenses.mit;
+        platforms = self.ghc.meta.platforms;
+      };
+    });
+in {
+  jsonRpcServer = let pair = versions : nameValuePair (toLabel versions) (build versions);
+                  in listToAttrs (map pair combos);
+}