feat(nix): Make derivation compatible for use without flakes

Author: Rixxc

default.nix

@@ -0,0 +1,26 @@
+{ pkgs ? import <nixpkgs> { }
+, jasminc
+}:
+with pkgs;
+stdenv.mkDerivation {
+  name = "libjade";
+  src = ./src;
+
+  nativeBuildInputs = with pkgs; [
+    jasminc
+    clang
+    gnumake
+  ];
+
+  buildPhase = ''
+    make FAIL_ON_ERROR=1 -j$(nproc)
+  '';
+
+  installPhase = ''
+    mkdir -p $out/lib
+    mkdir -p $out/include
+    cp libjade.a $out/lib/
+    cp libjade.h $out/include/
+  '';
+
+}

flake.nix

@@ -18,31 +18,10 @@
       ec = easycrypt.packages.${system}.default;
     in
     {
-      packages.${system}.default = pkgs.stdenv.mkDerivation {
-        name = "libjade";
-        src = ./src;
-
-        nativeBuildInputs = with pkgs; [
-          jasminc
-          clang
-          gnumake
-        ];
-
-        buildPhase = ''
-          make FAIL_ON_ERROR=1 -j$(nproc)
-        '';
-
-        installPhase = ''
-          mkdir -p $out/lib
-          mkdir -p $out/include
-          cp libjade.a $out/lib/
-          cp libjade.h $out/include/
-        '';
-
-      };
+      packages.${system}.default = pkgs.callPackage ./default.nix { inherit pkgs jasminc; };
 
       devShells.${system}.default = pkgs.mkShell {
-        name = "libjade-ci";
+        name = "libjade";
         src = self.packages.${system}.default.src;
 
         packages = self.packages.${system}.default.nativeBuildInputs ++