diff --git a/.gitignore b/.gitignore
index c27d6a7..2379caa 100644
--- a/.gitignore
+++ b/.gitignore
@@ -28,3 +28,4 @@ node_modules/
 .shadow-cljs
 .cljs_node_repl/
 .helix/
+target/repl-port
diff --git a/src/ludus/base.cljc b/src/ludus/base.cljc
index 0c5fa64..dbe7021 100644
--- a/src/ludus/base.cljc
+++ b/src/ludus/base.cljc
@@ -73,12 +73,11 @@
 
 (defn- stringify-args [arglist]
   (apply str (interpose " " (into [] (map print-show) (rest arglist)))))
-
-(def panic! {:name "panic!"
-             ::data/type ::data/clj
-             :body (fn panic-inner
-                     ([] (panic-inner [::data/list])) 
-                     ([args] (throw (ex-info (stringify-args args) {}))))})
+; (def panic! {:name "panic!"
+;              ::data/type ::data/clj
+;              :body (fn panic-inner
+;                      ([] (panic-inner [::data/list])) 
+;                      ([args] (throw (ex-info (stringify-args args) {}))))})
 
 (def print- {:name "print"
              ::data/type ::data/clj
@@ -410,7 +409,7 @@
            :to_vec to_vec
            :fold fold
            :map map
-           :panic! panic!
+           ; :panic! panic!
            :prn prn-
            :concat concat-
            :str str-
diff --git a/src/ludus/error.cljc b/src/ludus/error.cljc
index 22f2cf4..2fc5ec9 100644
--- a/src/ludus/error.cljc
+++ b/src/ludus/error.cljc
@@ -1,7 +1,7 @@
 (ns ludus.error
  	(:require [clojure.string :as string]))
 
-(defn get-line [source {:keys [line]}]
+(defn get-line [source line]
  	(let [lines (string/split-lines source)
      			the_line (nth lines (dec line))]
  			the_line))
@@ -21,22 +21,26 @@
 
 (defn scan-error [] :TODO)
 
-(defn parse-error [source {:keys [trace token]}]
- 	(let [line (get-line source token)
+(defn parse-error [{:keys [trace token]}]
+ 	(let [source (:source token)
+     			input (:input token)
+     			line-num (:line token)
+     			line (get-line source line-num)
       		line-num (:line token)
       		prefix (str line-num ": ")
       		underline (get-underline source token (count prefix))
       		expected (first trace)
       		got (:type token)
-      		message (str "Ludus found a parsing error on line " line-num ".\nExpected: " expected "\nGot: " got "\n")
+      		message (str "Ludus found a parsing error on line " line-num " in " input ".\nExpected: " expected "\nGot: " got "\n")
       		]
   		(str message "\n" prefix line "\n" underline)
   		)
  	)
 
-(defn run-error [source {:keys [line message]}]
- 	(if line
-  		(str "Ludus panicked on line " line ":\n" (get-line source {:line line}) "\n" message)
-  		(str "Ludus panicked!\n" message)
-  		))
+(defn run-error [{:keys [message token line]}]
+ 	(let [source (:source token) input (:input token)]
+   	(if line
+    		(str "Ludus panicked!: " message "\nOn line " line " in " input "\n" (get-line source line))
+    		(str "Ludus panicked!\n" message)
+    		)))
 
diff --git a/src/ludus/grammar.cljc b/src/ludus/grammar.cljc
index 2290430..47e0978 100644
--- a/src/ludus/grammar.cljc
+++ b/src/ludus/grammar.cljc
@@ -234,7 +234,9 @@
 (defp collection flat choice [;struct-literal 
                               dict list-literal set-literal tuple])
 
-(defp simple flat choice [literal collection synthetic recur-call lambda])
+(defp panic group order-1 [(quiet :panic) expression])
+
+(defp simple flat choice [literal collection synthetic recur-call lambda panic])
 
 (defp compound flat choice [match loop-expr if-expr when-expr do-expr block repeat-expr])
 
@@ -268,3 +270,4 @@
 (defp script order-0 [nls?
                       (one+ script-line)
                       (quiet :eof)])
+
diff --git a/src/ludus/interpreter.cljc b/src/ludus/interpreter.cljc
index 6b8b470..7d8fa28 100644
--- a/src/ludus/interpreter.cljc
+++ b/src/ludus/interpreter.cljc
@@ -817,11 +817,18 @@
 
 (defn- interpret-literal [ast] (-> ast :data first))
 
+(defn- interpret-panic [ast ctx]
+  (let [msg-value (interpret-ast (-> ast :data first) ctx)
+        msg-string (show/show msg-value)]
+    (throw (ex-info msg-string {:ast ast}))))
+
 (defn interpret-ast [ast ctx]
   (case (:type ast)
 
     (:nil :true :false :number :string :keyword) (interpret-literal ast)
 
+    :panic (interpret-panic ast ctx)
+
     :let-expr (interpret-let ast ctx)
 
     :if-expr (interpret-if ast ctx)
@@ -886,7 +893,7 @@
     ; :struct-literal
     ; (interpret-struct ast ctx)
 
-    (throw (ex-info (str "Unknown AST node type " (get ast :type :err) " on line " (get-in ast [:token :line])) {:ast ast}))))
+    (throw (ex-info (str "Unknown AST node type " (get ast :type :none) " on line " (get-in ast [:token :line])) {:ast ast}))))
 
 (defn get-line [source line]
   (if line
@@ -908,11 +915,11 @@
   (into {} (map-keys kw->str) ns))
 
 (def ludus-prelude 
-  (let [scanned (scanner/scan prelude/prelude)
+  (let [scanned (scanner/scan prelude/prelude "prelude")
         parsed (p/apply-parser g/script (:tokens scanned))
         ; _ (println "Parse status: " (:status parsed))
         ; _ (if (= :err (:status parsed))
-        ;     (throw (ex-info (error/parse-error prelude/prelude parsed) {})))
+        ;     (throw (ex-info (error/parse-error parsed) {})))
         base-ctx (volatile! {::parent (volatile! {"base" base/base})})
         interpreted (interpret-ast parsed base-ctx)
         namespace (dissoc interpreted ::data/type ::data/name ::data/struct)
@@ -973,28 +980,41 @@
         ;(pp/pprint (ex-data e))
         ;(throw e)
         {::data/error true 
+         :token (get-in (ex-data e) [:ast :token])
          :line (get-in (ex-data e) [:ast :token :line])
          :message (ex-message e)}
         ))))
 
+; No prelude; helps when there are errors in the prelude
+(defn interpret-bare [source parsed ctx]
+  (let [base-ctx (volatile! {::parent (volatile! ctx)})]
+    (try
+      (interpret-ast parsed base-ctx)
+      (catch #?(:clj Throwable :cljs js/Object) e
+        {::data/error true
+         :token (get-in (ex-data e) [:ast :token])
+         :line (get-in (ex-data e) [:ast :token :line])
+         :message (ex-message e)}))))
+
 
 ;; repl
 (comment
-   
+ 
   (println "***********")
 
   (def source "
-    let times = 1.3
-    repeat times { print! (:foo) }
+    panic! (:oh, :no)
 ")
 
-  (def tokens (-> source scanner/scan :tokens))
+  (def tokens (-> source (scanner/scan "test input") :tokens))
 
   (def ast (p/apply-parser g/script tokens))
 
-  (def result (interpret-safe source ast {}))
+  (def result (interpret-bare source ast {}))
 
-  ;(-> ast prettify-ast println)
+  (println tokens)
+
+  (-> ast prettify-ast println)
 
   (println result)  
 
diff --git a/src/ludus/node.cljc b/src/ludus/node.cljc
index a1708b3..d63f27a 100644
--- a/src/ludus/node.cljc
+++ b/src/ludus/node.cljc
@@ -31,14 +31,12 @@
  	#?(:clj value :cljs (clj->js value)))
 
 (defn run [source]
- 	(let [user_scanned (s/scan source)
+ 	(let [user_scanned (s/scan source "user input")
       		user_tokens (:tokens user_scanned)
-        _ (println "Tokens: " user_tokens)
       		user_parsed (p/apply-parser g/script user_tokens)
-        _ (println "Ast: " (i/prettify-ast user_parsed))
       		user_result (i/interpret-safe source user_parsed {})
       		result_str (show/show user_result)
-      		post_scanned (s/scan pre/postlude)
+      		post_scanned (s/scan pre/postlude "postlude")
       		post_tokens (:tokens post_scanned)
       		post_parsed (p/apply-parser g/script post_tokens)
       		post_result (i/interpret-safe source post_parsed {})
@@ -50,13 +48,24 @@
      	(clean-out {:errors (:errors user_tokens)})
 
      	(= :err (:status user_parsed))
-     	(clean-out {:errors [(error/parse-error source user_parsed)]})
+     	(clean-out {:errors [(error/parse-error user_parsed)]})
 
      	(::data/error user_result)
-     	(clean-out (assoc (ld->clj post_result) :errors [(error/run-error source user_result)]))
+     	(clean-out (assoc (ld->clj post_result) :errors [(error/run-error user_result)]))
 
      	:else
      	(clean-out clj_result)
      	)
    	))
 
+(comment
+  (def source "
+
+    a b c
+
+    ")
+
+  (-> source run :errors println)
+  )
+
+
diff --git a/src/ludus/prelude.ld b/src/ludus/prelude.ld
index e3e62f9..5afd761 100644
--- a/src/ludus/prelude.ld
+++ b/src/ludus/prelude.ld
@@ -276,19 +276,6 @@ fn report! {
 	}
 }
 
-fn panic! {
-	"Causes Ludus to panic, outputting any arguments as messages."
-	() -> {
-		add_msg! ("Ludus panicked!")
-		base :panic! ()
-	}
-	(...args) -> {
-		add_msg! ("Ludus panicked!")
-		add_msg! (args)
-		base :panic! (args)
-	}
-}
-
 fn doc! {
 	"Prints the documentation of a function to the console."
 	(f as :fn) -> do f > base :doc > print!
@@ -396,7 +383,7 @@ fn mult {
 fn div {
 	"Divides numbers. Panics on division by zero."
 	(x as :number) -> x
-	(_, 0) -> panic! ("Division by zero.")
+	(_, 0) -> panic! "Division by zero."
 	(x as :number, y as :number) -> base :div (x, y)
 	(x, y, ...zs) -> {
 		let divisor = fold (mult, zs, y)
@@ -898,8 +885,8 @@ fn err? {
 fn unwrap! {
 	"Takes a result tuple. If it's :ok, then returns the value. If it's not :ok, then it panics. If it's not a result tuple, it also panics."
 	((:ok, value)) -> value
-	((:err, msg)) -> panic! ("Unwrapped :err", msg)
-	(_) -> panic! ("Cannot unwrap something that's not an error tuple.")
+	((:err, msg)) -> panic! string ("Unwrapped :err! ", msg)
+	(_) -> panic! "Cannot unwrap something that's not an error tuple."
 }
 
 fn unwrap_or {
@@ -910,10 +897,10 @@ fn unwrap_or {
 
 fn assert! {
 	"Asserts a condition: returns the value if the value is truthy, panics if the value is falsy. Takes an optional message."
-	(value) -> if value then value else panic! ("Assert failed", value)
-	(value, message) -> if value 
+	(value) -> if value then value else panic! string ("Assert failed:", value)
+	(msg, value) -> if value 
 		then value 
-		else panic! ("Assert failed:", message, value)
+		else panic! string ("Assert failed: ", msg, " with ", value)
 }
 
 &&& Turtle & other graphics
@@ -1217,7 +1204,6 @@ ns prelude {
 	show
 	prn!
 	report!
-	panic!
 	doc!
 	concat
 	ref?
diff --git a/src/ludus/scanner.cljc b/src/ludus/scanner.cljc
index b0a9fde..f55531a 100644
--- a/src/ludus/scanner.cljc
+++ b/src/ludus/scanner.cljc
@@ -20,7 +20,7 @@
    "match" :match ;; impl
    "nil" :nil ;; impl -> literal word
    "ns" :ns ;; impl
-   ;; "panic!" :panic ;; impl (should be a function)
+   "panic!" :panic ;; impl (should _not_ be a function)
    "recur" :recur ;; impl
    "ref" :ref ;; impl
    "then" :then ;; impl
@@ -51,8 +51,9 @@
 
 (defn- new-scanner
   "Creates a new scanner."
-  [source]
+  [source input]
   {:source source
+   :input input
    :length (count source)
    :errors []
    :start 0
@@ -135,7 +136,9 @@
        (current-lexeme scanner)
        literal
        (:line scanner)
-       (:start scanner)))))
+       (:start scanner)
+       (:source scanner)
+       (:input scanner)))))
 
 ;; TODO: errors should also be in the vector of tokens
 ;; The goal is to be able to be able to hand this to an LSP?
@@ -146,7 +149,9 @@
                 (current-lexeme scanner)
                 nil
                 (:line scanner)
-                (:start scanner))
+                (:start scanner)
+                (:source scanner)
+                (:input scanner))
         err-token (assoc token :message msg)]
     (-> scanner
       (update :errors conj err-token)
@@ -240,7 +245,7 @@
          comm (str char)]
     (let [char (current-char scanner)]
       (if (= \newline char)
-        (update scanner :line inc)
+        scanner
         (recur (advance scanner) (str comm char))))))
 
 (defn- scan-token [scanner]
@@ -322,11 +327,10 @@
 (defn- next-token [scanner]
   (assoc scanner :start (:current scanner)))
 
-(defn scan [source]
-  (loop [scanner (new-scanner source)]
+(defn scan [source input]
+  (loop [scanner (new-scanner source input)]
     (if (at-end? scanner)
       (let [scanner (add-token (add-token scanner :break) :eof)]
         {:tokens (:tokens scanner)
          :errors (:errors scanner)})
       (recur (-> scanner (scan-token) (next-token))))))
-
diff --git a/src/ludus/token.cljc b/src/ludus/token.cljc
index 5188fbd..6638bc0 100644
--- a/src/ludus/token.cljc
+++ b/src/ludus/token.cljc
@@ -1,9 +1,11 @@
 (ns ludus.token)
 
 (defn token
-  [type text literal line start]
+  [type text literal line start source input]
   {:type type
    :lexeme text
    :literal literal
    :line line
+   :source source
+   :input input
    :start start})
diff --git a/target/repl-port b/target/repl-port
deleted file mode 100644
index 8dbb69f..0000000
--- a/target/repl-port
+++ /dev/null
@@ -1 +0,0 @@
-51500
\ No newline at end of file