5 files changed, 34 insertions, 13 deletions
diff --git a/nix/nixpkgs.nix b/nix/default.nix
index 864511b..74917f8 100644
--- a/nix/nixpkgs.nix
+++ b/nix/default.nix
@@ -5,6 +5,8 @@ let
     overlays = [
       (_: _: { inherit sources; })
       (_: _: { niv = import sources.niv {}; })
+      (import ./sources-overlay.nix)
+      (_: pkgs: pkgs.overridePinnedDeps pkgs.overrideSource)
       (import ./haskell-overlay.nix)
       (_: pkgs: { wemux = pkgs.callPackage ./wemux.nix {}; })
     ];
diff --git a/nix/haskell-overlay.nix b/nix/haskell-overlay.nix
index e384b4f..1afea87 100644
--- a/nix/haskell-overlay.nix
+++ b/nix/haskell-overlay.nix
@@ -1,24 +1,26 @@
-_: nixpkgs:
+_: pkgs:
 
+let
+  cabalBuilder = self: name: self.callCabal2nix name pkgs.sources.${name} {};
+in
 {
-  haskell = nixpkgs.haskell // {
-    packages = nixpkgs.haskell.packages // {
-      ghc865 = nixpkgs.haskell.packages.ghc865.override (old: {
-        overrides = with nixpkgs.pkgs.haskell.lib; self: super: {
-          clay = self.callCabal2nix "clay" nixpkgs.sources.clay {};
-          miso = self.callCabal2nix "miso" nixpkgs.sources.miso {};
+  haskell = pkgs.haskell // {
+    packages = pkgs.haskell.packages // {
+      ghc865 = pkgs.haskell.packages.ghc865.override (old: {
+        overrides = with pkgs.pkgs.haskell.lib; self: super:
+          pkgs.overridePinnedDeps (cabalBuilder self) // {
           wai-middleware-metrics = dontCheck super.wai-middleware-metrics;
         };
       });
-      ghcjs = nixpkgs.haskell.packages.ghcjs.override (old: {
-        overrides = with nixpkgs.haskell.lib; self: super: {
+      ghcjs = pkgs.haskell.packages.ghcjs.override (old: {
+        overrides = with pkgs.haskell.lib; self: super:
+          pkgs.overridePinnedDeps (cabalBuilder self) // {
           QuickCheck = dontCheck super.QuickCheck;
           base-compat-batteries = dontCheck super.http-types;
-          clay = dontCheck (self.callCabal2nix "clay" claySrc {});
+          clay = dontCheck super.clay;
           comonad = dontCheck super.comonad;
-          jsaddle-warp = dontCheck (self.callCabal2nix "jsaddle-warp" "${nixpkgs.sources.jsaddle}/jsaddle-warp" {});
+          jsaddle-warp = dontCheck (self.callCabal2nix "jsaddle-warp" "${pkgs.sources.jsaddle}/jsaddle-warp" {});
           http-types = dontCheck super.http-types;
-          miso = self.callCabal2nix "miso" nixpkgs.sources.miso {};
           network-uri= dontCheck super.network-uri;
           scientific = dontCheck super.scientific; # takes forever
           servant = dontCheck super.servant;
diff --git a/nix/repl.nix b/nix/repl.nix
new file mode 100644
index 0000000..94edf3a
--- /dev/null
+++ b/nix/repl.nix
@@ -0,0 +1 @@
+{ nixpkgs = import ./.; }
diff --git a/nix/sources-overlay.nix b/nix/sources-overlay.nix
new file mode 100644
index 0000000..b19bb34
--- /dev/null
+++ b/nix/sources-overlay.nix
@@ -0,0 +1,16 @@
+_: pkgs:
+
+rec {
+  pinnedDeps = builtins.attrNames
+    (builtins.removeAttrs pkgs.sources ["__functor"]);
+  overridePinnedDeps = builder: pkgs.lib.genAttrs pinnedDeps builder;
+
+  # Modifies a derivation with our source and version, keeping old build
+  # rules. This will fail if build steps have changed, or if no build
+  # rules are available upstream..
+  overrideSource = name: pkgs.${name}.overrideAttrs (old: old // rec {
+    name = "${name}-${version}";
+    version = pkgs.sources.${name}.version or pkgs.sources.${name}.rev;
+    src = pkgs.sources.${name};
+  });
+}
diff --git a/nix/wemux.nix b/nix/wemux.nix
index 4972815..365853f 100644
--- a/nix/wemux.nix
+++ b/nix/wemux.nix
@@ -1,7 +1,7 @@
 { sources, stdenv }:
 
 stdenv.mkDerivation rec {
-  name = "wemux";
+  name = "wemux-${version}";
   version = "2020.04.03";
   src = sources.wemux;
   installPhase = ''