diff --git a/.gitignore b/.gitignore
index 2091ad0..f187998 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,6 +8,9 @@ pom.xml.asc
 *.class
 /lib/
 /classes/
+/bin/
+/node_modules/
+/.lumo_cache/
 /target/
 /checkouts/
 .lein-deps-sum
diff --git a/build.clj b/build.clj
new file mode 100644
index 0000000..2b16597
--- /dev/null
+++ b/build.clj
@@ -0,0 +1,31 @@
+(ns build
+  (:require [clojure.tools.build.api :as b]
+            [clojure.java.shell :as sh]))
+
+(def lib 'net.cgrand/xforms)
+(def version "0.19.5"  #_(format "0.0.%s" (b/git-count-revs nil)))
+(def class-dir "target/classes")
+(def basis (b/create-basis {:project "deps.edn"}))
+(def jar-file (format "target/%s-%s.jar" (name lib) version))
+
+(defn clean [_]
+  (b/delete {:path "target"}))
+
+(defn jar [_]
+  (b/write-pom {:class-dir class-dir
+                :lib lib
+                :version version
+                :basis basis
+                :src-dirs ["src"]})
+  (b/copy-dir {:src-dirs ["src" "resources"]
+               :target-dir class-dir})
+  (b/jar {:class-dir class-dir
+          :jar-file jar-file}))
+
+(defn clojars [_]
+  (sh/sh
+    "mvn" "deploy:deploy-file" (str "-Dfile=" jar-file)
+;target/classes/META-INF/maven/net.cgrand/xforms/pom.xml
+    (format "-DpomFile=%s/META-INF/maven/%s/%s/pom.xml"
+      class-dir (namespace lib) (name lib))
+    "-DrepositoryId=clojars" "-Durl=https://clojars.org/repo/"))
diff --git a/deps.edn b/deps.edn
index 93ab2fc..3d6e67b 100644
--- a/deps.edn
+++ b/deps.edn
@@ -1,4 +1,4 @@
-{:deps {net.cgrand/macrovich {:mvn/version "0.2.1"}}
+{:deps {net.cgrand/macrovich {:mvn/version "0.2.2"}}
  :paths ["src"]
 
  :aliases
@@ -8,8 +8,7 @@
   :cljd
   {:extra-deps
    {tensegritics/clojuredart
-    {:local/root "../../../cljd/open-source/ClojureDart"}
-    #_{:git/url "https://github.com/tensegritics/ClojureDart.git"
+    {:git/url "https://github.com/tensegritics/ClojureDart.git"
        :sha "ae1b485e84ccc35b122f776dfc7cc62198274701"}}}
 
   :clj-1-9
@@ -31,9 +30,15 @@
   {:extra-paths ["test"]}
 
   :kaocha
-  {:extra-deps {lambdaisland/kaocha {:mvn/version "1.69.1069"}}
+  {:extra-paths ["test"]
+   :extra-deps {lambdaisland/kaocha {:mvn/version "1.69.1069"}}
    :main-opts ["-m" "kaocha.runner"]}
 
   :cljs-test-runner
-  {:extra-deps {olical/cljs-test-runner {:mvn/version "3.8.0"}}
-   :main-opts ["-m" "cljs-test-runner.main"]}}}
+  {:extra-paths ["test"]
+   :extra-deps {olical/cljs-test-runner {:mvn/version "3.8.0"}}
+   :main-opts ["-m" "cljs-test-runner.main"]}
+
+  :build
+  {:deps {io.github.clojure/tools.build {:git/tag "v0.9.4" :git/sha "76b78fe"}}
+          :ns-default build}}}
diff --git a/project.clj b/project.clj
deleted file mode 100644
index 0c278ac..0000000
--- a/project.clj
+++ /dev/null
@@ -1,14 +0,0 @@
-(defproject net.cgrand/xforms "0.19.4"
-  :description "Extra transducers for Clojure"
-  :url "https://github.com/cgrand/xforms"
-  :license {:name "Eclipse Public License"
-            :url "http://www.eclipse.org/legal/epl-v10.html"}
-
-  :plugins [[lein-tools-deps "0.4.5"]]
-  :middleware [lein-tools-deps.plugin/resolve-dependencies-with-deps-edn]
-  :lein-tools-deps/config {:config-files [:project]}
-
-  :profiles
-  {:provided
-   {:dependencies [[org.clojure/clojure "1.8.0"]
-                   [org.clojure/clojurescript "1.9.293"]]}})
diff --git a/src/net/cgrand/xforms/rfs.cljc b/src/net/cgrand/xforms/rfs.cljc
index 9f80c51..8a389d0 100644
--- a/src/net/cgrand/xforms/rfs.cljc
+++ b/src/net/cgrand/xforms/rfs.cljc
@@ -95,7 +95,7 @@
   ([#?(:cljd ^{:tag #/(List? double)} acc :clj ^doubles acc :cljs ^doubles acc)]
    (when acc (/ (aget acc 1) (aget acc 0))))
   ([acc x] (avg acc x 1))
-  ([#?(:cljd ^{:tag #/(List? double)} acc :clj ^doubles acc :cljs ^doubles acc) x w]
+  ([#?(:cljd ^{:tag #/(List? double)} acc :clj ^doubles acc :cljs ^doubles acc) x w] ; weighted mean
     (let [acc (or acc #?(:cljd (double-array 2) :clj (double-array 2) :cljs #js [0.0 0.0]))]
       (doto acc
         (aset 0 (+ (aget acc 0) w))