diff --git a/deps.edn b/deps.edn
index 43014bc..dad6c27 100644
--- a/deps.edn
+++ b/deps.edn
@@ -1,6 +1,7 @@
 {:deps
  {org.clojure/clojurescript {:mvn/version "1.11.121"}
   thheller/shadow-cljs {:mvn/version "2.26.0"}
+  babashka/fs {:mvn/version "0.4.19"}
  }
 
  :aliases
diff --git a/project.clj b/project.clj
index 00f5f78..43d9e8d 100644
--- a/project.clj
+++ b/project.clj
@@ -4,7 +4,7 @@
   :license {:name "EPL-2.0 OR GPL-2.0-or-later WITH Classpath-exception-2.0"
             :url "https://www.eclipse.org/legal/epl-2.0/"}
   :dependencies [[org.clojure/clojure "1.11.1"]
-                 ;[babashka/fs "0.1.6"]
+                 [babashka/fs "0.1.6"]
                  ;[quil "4.0.0-SNAPSHOT"]
                  ]
   :plugins [[lein-cljfmt "0.8.0"]]
diff --git a/src/ludus/grammar.cljc b/src/ludus/grammar.cljc
index 2fa5909..f927ffd 100644
--- a/src/ludus/grammar.cljc
+++ b/src/ludus/grammar.cljc
@@ -249,7 +249,7 @@
                             	(zero+ struct-entry)
                             	(quiet :rbrace)])
 
-(defp use-expr group order-1 [(quiet :use :word)])
+(defp use-expr group order-1 [:use :word])
 
 (defp toplevel flat choice [import-expr
                             ns-expr
diff --git a/src/ludus/interpreter.cljc b/src/ludus/interpreter.cljc
index 3a39a70..19a100b 100644
--- a/src/ludus/interpreter.cljc
+++ b/src/ludus/interpreter.cljc
@@ -769,7 +769,7 @@
 
     :match (interpret-match ast ctx)
 
-    :cond-expr (interpret-cond ast ctx)
+    :when-expr (interpret-cond ast ctx)
 
     :fn-expr (interpret-fn ast ctx)
 
@@ -783,7 +783,7 @@
 
     :ref-expr (interpret-ref ast ctx)
 
-    :when-expr (interpret-ast (-> ast :data first) ctx)
+    ;:when-expr (interpret-ast (-> ast :data first) ctx)
 
     :recur-call
     {::data/recur true :args (interpret-ast (-> ast :data first) ctx)}
@@ -859,5 +859,29 @@
        (println ">>> " (get-line source (get-in (ex-data e) [:ast :token :line])))
        (println (ex-message e))
        (pp/pprint (ex-data e)
-         ;;(System/exit 67)
-         )))))
\ No newline at end of file
+         #?(:clj (System/exit 67))
+         )))))
+
+;; TODO: update this to use new parser pipeline & new AST representation
+(defn interpret-file [source path parsed]
+  (try 
+    (let [base-ctx (volatile! {::parent (volatile! prelude/prelude) :file path})]
+      (interpret-ast parsed base-ctx))
+    (catch clojure.lang.ExceptionInfo e
+      (println "Ludus panicked in" path)
+      (println "On line" (get-in (ex-data e) [:ast :token :line]))
+      (println ">>> " (get-line source (get-in (ex-data e) [:ast :token :line])))
+      (println (ex-message e))
+      (System/exit 67))))
+
+;; TODO: update this to use new parser pipeline & new AST representation
+(defn interpret-repl
+  ([parsed ctx]
+   (let [orig-ctx @ctx]
+     (try
+       (let [result (interpret-ast parsed ctx)]
+         {:result result :ctx ctx})
+       (catch clojure.lang.ExceptionInfo e
+         (println "Ludus panicked!")
+         (println (ex-message e))
+         {:result :error :ctx (volatile! orig-ctx)})))))
diff --git a/src/ludus/repl.clj b/src/ludus/repl.clj
index 6455f48..7069344 100644
--- a/src/ludus/repl.clj
+++ b/src/ludus/repl.clj
@@ -1,8 +1,7 @@
 (ns ludus.repl
   (:require
     [ludus.scanner :as scanner]
-    ;[ludus.parser :as parser]
-    [ludus.parser-new :as p]
+    [ludus.parser :as p]
     [ludus.grammar :as g]
     [ludus.interpreter :as interpreter]
     [ludus.prelude :as prelude]
@@ -83,8 +82,7 @@
 (defn repl-loop []
   (let [session-atom @current-session
         session @session-atom
-        orig-ctx (:ctx session)
-        pid (:pid session)]
+        orig-ctx (:ctx session)]
     (print (str (:name session) prompt))
     (flush)
     (let [input (read-line)]
@@ -102,18 +100,14 @@
             (do
               (println (p/err-msg parsed))
               (recur))
-            (let [{result :result ctx :ctx pid- :pid}
-                  (if pid
-                    (interpreter/interpret-repl parsed orig-ctx pid)
-                    (interpreter/interpret-repl parsed orig-ctx))]
+            (let [{result :result ctx :ctx}
+                  (interpreter/interpret-repl parsed orig-ctx)]
               (if (= result :error)
                 (recur)
                 (do
                   (println (show/show result))
                   (when (not (= @ctx @orig-ctx))
                     (swap! session-atom #(assoc % :ctx ctx)))
-                  (when (not (= pid pid-))
-                    (swap! session-atom #(assoc % :pid pid-)))
                   (recur))))))))))
 
 (defn launch []