Am I even using this?

build.tools.nix

@@ -21,7 +21,6 @@ let
     echo "building namespace: ${ns}"...
     java -cp .:${classpath} clojure.main -e "(compile ${ns})"
   '';
-  head-or-null = lst: if (lst == [ ]) then null else head lst;
   matches-ext = ext: filename: (builtins.match ".+[.]${ext}$" filename) != null;
   strip-ext = ext: filename:
     head-or-null (builtins.match "(.+)[.]${ext}$" filename);

mkClojureLib.nix

@@ -1,58 +1,96 @@
 { lib, stdenv, callPackage, clojure, jre, writeText, writeShellScript, toEDN }:
-{ src, name, group, version, deps-edn, clj-deps, src-paths, build-tools-jar, ...
-}:
+{ src, name, group, version, clj-deps, src-paths, ... }:
 
 with lib;
 let
-  build-tools-deps = toEDN {
-    aliases.build = {
-      extra-deps."'io.github.clojure/tools.build"."local/root" =
-        ''\"${build-tools-jar}\"'';
-    };
-  };
-
   classpath = clj-deps.makeClasspaths { };
+  deps-jars = splitString ":" classpath;
 
-  build-deps = callPackage ./deps.nix { };
-  build-classpath = build-deps.makeClasspaths { };
+  full-name = "${name}-${version}-standalone";
 
-  full-name = "${name}-${version}-standalone.jar";
+  manifest = writeText "MANIFEST.MF" ''
+    Manifest-Version: 1.0
 
-  target = "$TEMP/target";
+  '';
 
-  build-script = writeShellScript "create-uberjar.sh" ''
-    HOME=$TEMP/home
-    mkdir -p $HOME
-    mkdir -p ${target}
+  extract-jar = jar: ''
+    echo jar -xf ${jar}
+    jar -xf ${jar}
+  '';
 
-    clojure       \
-      -Scp        ${build-classpath}:${classpath}:${build-tools-jar}:. \
-      -Sdeps      "${build-tools-deps}" \
-      -X:build    \
-      build/lib-uberjar \
-      :project    ${group}/${name} \
-      :version    ${version} \
-      :src-dirs   ${concatStringsSep "," src-paths} \
-      :target     '"${target}"' \
-      :deps-edn   '"${deps-edn}"'
+  clj-compile = classpath: ns: ''
+    echo java -cp .:${classpath} clojure.main -e "(compile ${ns})"
+    java -cp .:${classpath} clojure.main -e "(compile ${ns})"
+  '';
 
-    [ $? -eq 0 ] || cat /tmp/*.edn
+  matches-ext = ext: filename: (builtins.match ".+[.]${ext}$" filename) != null;
+  strip-ext = ext: filename:
+    builtins.head (builtins.match "(.+)[.]${ext}$" filename);
+
+  concatMapAttrs = f: attrs: concatLists (mapAttrsToList f attrs);
+
+  find-files = pred: path:
+    let
+      find-files-impl = base:
+        concatMapAttrs (handle-file base) (builtins.readDir base);
+      handle-file = base: name: type:
+        if (type == "directory") then
+          find-files-impl "${base}/${name}"
+        else
+          (if (pred name) then [ "${base}/${name}" ] else [ ]);
+    in find-files-impl path;
+
+  file-to-namespace = base: filename:
+    let
+      swap-chars = replaceStrings [ "_" "/" ] [ "-" "." ];
+      strip-clj = strip-ext "clj";
+      strip-base = replaceStrings [ "${base}/" ] [ "" ];
+      ns = swap-chars (strip-base (strip-clj (toString filename)));
+    in "'${ns}";
+
+  target-namespaces = concatMap (subdir:
+    let dir = src + "/${subdir}";
+    in map (file-to-namespace dir) (find-files (matches-ext "clj") dir))
+    src-paths;
+
+  copy-source-path = target: subdir: "cp -R ${src}/${subdir}/* ${target}";
+
+  build-script = let
+    join-lines = concatStringsSep "\n";
+    srcs = concatStringsSep ":" (map (path: "./${path}") src-paths);
+  in writeShellScript "create-${full-name}-uberjar.sh" ''
+    HOME=./home
+    mkdir $HOME
+    mkdir classes
+
+    mkdir ./deps
+    cd ./deps
+    ${join-lines (map extract-jar deps-jars)}
+    cd ..
+    ${join-lines
+    (map (clj-compile "${classpath}:${srcs}:./deps") target-namespaces)}
+    mkdir target
+    cp -R classes/* target/
+    ${join-lines (map (copy-source-path "./target/") src-paths)}
+    cp -R deps/* target/
+    cp ./deps.edn ./target/deps.edn
+    cd target
+    jar cmf ${manifest} ../out.jar -C . ./*
   '';
 
   pthru = o: builtins.trace o o;
 
 in stdenv.mkDerivation {
-  name = full-name;
+  name = "${full-name}.jar";
 
   src = src;
 
-  nativeBuildInputs = [ clojure jre ];
-  buildInputs = (map (x: x.paths) clj-deps.packages)
-    ++ (map (x: x.paths) build-deps.packages);
+  nativeBuildInputs = [ jre ];
+  buildInputs = map (x: x.paths) clj-deps.packages;
 
-  buildPhase = pthru "${build-script}";
+  buildPhase = "${build-script}";
 
   installPhase = ''
-    mv ${target}/${name}-${version}-standalone.jar $out
+    mv out.jar $out
   '';
 }