diff --git a/.gitignore b/.gitignore
index ddfe040..0b65f21 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,3 +10,7 @@
 .hgignore
 .hg/
 .DS_Store
+.lsp
+.lh
+.calva
+.clj-kondo
diff --git a/src/jcpsantiago/bulgogi.clj b/src/jcpsantiago/bulgogi.clj
index 3f9b56e..7664798 100644
--- a/src/jcpsantiago/bulgogi.clj
+++ b/src/jcpsantiago/bulgogi.clj
@@ -1,12 +1,38 @@
 (ns jcpsantiago.bulgogi
   " À-la-carte transformations of data, useful in ML systems.")
 
+(defn- update-keys [m f]
+  (reduce-kv (fn [m k v]
+               (assoc m (f k) v)) {} m))
+               
+(defn- all-special-functions
+  "Returns a map of feature-name -> feature-var"
+  ([fn-type]
+   (all-special-functions fn-type true))
+  ([fn-type namespaced?]
+   (->> (all-ns)
+        (filter #(fn-type (meta %)))
+        (map (fn [ns] (update-keys (ns-publics ns) #(if namespaced? (symbol (str ns) (str %)) %))))
+        (apply merge-with #(throw (Exception. (str "Conflict between: " %1 " and :" %2)))))))
+
+
+(defn all-features
+  "Returns a map of feature-name -> fn-var"
+  []
+  (all-special-functions ::features false))
+
+
+(defn all-coeffects
+  "Returns a map of coeffect-name -> fn-var"
+  []
+  (all-special-functions ::coeffects))
+
 
 (defn- resolved-features
-  [features -ns]
-  (->> features
-       (map #(let [sym (symbol %)]
-               (ns-resolve (find-ns -ns) sym)))))
+  [features]
+  (let [all (all-features)]
+    (->> features
+         (map #(get all (symbol %))))))
 
 
 (defn- transformed
@@ -14,6 +40,28 @@
   (pmap #(% input-data) fns))
 
 
+(defn- enriched
+  [input-data fns]
+  (if (empty? fns)
+    input-data
+    (->> fns
+         (pmap #(% input-data))
+         (apply merge))))
+
+
+(def ^:private memoized-features
+  (memoize resolved-features))
+
+
+(def ^:private memoized-coeffects
+  (memoize (fn [fn-vars]
+             (let [all (all-coeffects)]
+               (->> fn-vars
+                    (map #(:bulgogi/coeffect (meta %)))
+                    (remove nil?)
+                    (map #(all (symbol %))))))))
+
+
 (defn preprocessed
   "
   Takes a request map with keys :input-data and :features.
@@ -29,9 +77,22 @@
   Looks for the features in the namespace and applies them to the input-data
   in parallel. Returns a map of feature-keys and feature-values.
   "
-  [req -ns]
+  [req]
   (let [{:keys [input-data features]} req
-        fns (resolved-features features -ns)
+        fns (memoized-features features)
+        coeffects (memoized-coeffects fns)
         fn-ks (map keyword features)]
-    (->> (transformed input-data fns)
+    (->> (transformed (enriched input-data coeffects) fns)
          (zipmap fn-ks))))
+
+
+(defn- feature-conflicts? []
+  (->> (all-features)       
+       (mapcat keys)
+       distinct?))
+
+(all-features)
+
+(comment
+  (all-features)
+  (feature-conflicts?))
\ No newline at end of file
diff --git a/test/jcpsantiago/bulgogi_test.clj b/test/jcpsantiago/bulgogi_test.clj
index 766a72c..500b224 100644
--- a/test/jcpsantiago/bulgogi_test.clj
+++ b/test/jcpsantiago/bulgogi_test.clj
@@ -1,9 +1,125 @@
 (ns jcpsantiago.bulgogi-test
+  {:jcpsantiago.bulgogi/features true
+   :jcpsantiago.bulgogi/coeffects true}
   (:require
-    [clojure.test :refer :all]
-    [jcpsantiago.bulgogi :refer :all]))
+   [clojure.string :as s]
+   [clojure.test :refer :all]
+   [clojure.set]
+   [jcpsantiago.features]
+   [jcpsantiago.bulgogi :as SUT]))
 
 
-(deftest a-test
-  (testing "will be gone soon :D"
-    (is (= 1 1))))
+(defn boolean->int
+  "Cast a boolean to 1/0 integer indicator"
+  [b]
+  (when boolean? b
+        (if (true? b) 1 0)))
+
+
+(defn email-name
+  "Lower-cased name of an email address (the bit before @)"
+  [email]
+  (-> email
+      s/lower-case
+      (s/replace-first #"@.*" "")))
+
+
+(defn n-digits-in-email-name
+  "Number of digits in the email name"
+  [{email :email}]
+  (->> (email-name email)
+       (re-seq #"\d")
+       count))
+
+
+(defn n-chars-in-email-name
+  "Number of characters in the email name i.e. length of the email name"
+  [{email :email}]
+  (-> (email-name email)
+      count))
+
+
+(defn diff-eur-previous-order
+  "Difference in euros between the current order and the previous one."
+  [{current-amount :current-amount previous-amount :previous-amount}]
+  (- current-amount previous-amount))
+
+
+(defn risky-item?
+  "Boolean depending on whether an item is risky or not"
+  [{brand :brand}]
+  (->> brand
+       s/lower-case
+       (re-seq #"baz corp")
+       some?
+       boolean->int))
+
+
+(defn contains-risky-item
+  "Indicator 1/0 depending on whether a risky item is present in the cart"
+  [{items :items}]
+  (->> items
+       (map #(risky-item? %))
+       (some #(= 1 %))
+       boolean->int))
+
+
+(defn ^{:bulgogi/coeffect ::added} needs-coeffect
+  [{data ::added}]
+  data)
+
+
+(defn added
+  [_]
+  {::added "some data"})
+
+
+(defn email-name-as-coeffect
+  [{email :email}]
+  {::email-name-as-coeffect (-> email
+                                s/lower-case
+                                (s/replace-first #"@.*" ""))})
+
+
+(defn ^{:bulgogi/coeffect ::email-name-as-coeffect} n-chars-in-email-name-w-coeffect
+  [{email-name-as-coeffect ::email-name-as-coeffect}]
+  (count email-name-as-coeffect))
+
+
+(def test-input
+  {:current-amount 700
+   :previous-amount 400
+   :email "squadron42@starfleet.ufp"
+   :items [{:brand "Foo Industries" :value 1234}
+           {:brand "Baz Corp" :value 35345}]})
+
+
+(deftest preprocessed
+  (testing "basics"
+    (is (= {:contains-risky-item 1
+            :diff-eur-previous-order 300
+            :n-digits-in-email-name 2}
+           (SUT/preprocessed {:input-data test-input
+                              :features ["n-digits-in-email-name"
+                                         "contains-risky-item"
+                                         "diff-eur-previous-order"]}
+                             ))))
+  (testing "coeffect"
+    (is (= {:needs-coeffect "some data"}
+           (SUT/preprocessed {:input-data test-input
+                              :features ["needs-coeffect"]}
+                             ))))
+  (testing "coeffect complex feature"
+    (is (= {:n-chars-in-email-name-w-coeffect 10}
+           (SUT/preprocessed {:input-data test-input
+                              :features ["n-chars-in-email-name-w-coeffect"]}
+                             )))))
+
+(deftest all-features
+  (testing "finds features in marked ns"
+    (is (clojure.set/subset? #{'distinct-feature1 'feature1}
+                             (set (keys (SUT/all-features))))))
+  (testing "throws on conflict"
+    (require '[jcpsantiago.features2])
+    (is (thrown-with-msg? Exception #"^Conflict" (SUT/all-features)))))
+
diff --git a/test/jcpsantiago/features.clj b/test/jcpsantiago/features.clj
new file mode 100644
index 0000000..8cf20c2
--- /dev/null
+++ b/test/jcpsantiago/features.clj
@@ -0,0 +1,8 @@
+(ns jcpsantiago.features
+  {:jcpsantiago.bulgogi/features true})
+
+(defn feature1 [_]
+  (inc 1))
+
+(defn distinct-feature1 []
+  "some")
\ No newline at end of file
diff --git a/test/jcpsantiago/features2.clj b/test/jcpsantiago/features2.clj
new file mode 100644
index 0000000..e53f43d
--- /dev/null
+++ b/test/jcpsantiago/features2.clj
@@ -0,0 +1,8 @@
+(ns jcpsantiago.features2
+  {:jcpsantiago.bulgogi/features true})
+
+(defn feature1 [_]
+  (inc 1))
+
+(defn distinct-feature2 []
+  "some")
\ No newline at end of file