diff --git a/justfile b/justfile
index 6aacdfe..063793e 100644
--- a/justfile
+++ b/justfile
@@ -1,3 +1,6 @@
 # start a repl
 repl:
-	clj -X:repl
\ No newline at end of file
+	clj -X:repl
+
+build:
+	shadow-cljs release node
diff --git a/package.json b/package.json
index 41e03a0..095ff81 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@ludus/ludus-js-pure",
-  "version": "0.1.0-alpha.5",
+  "version": "0.1.0-alpha.7.6",
   "description": "A Ludus interpreter in a pure JS function.",
   "main": "target/js/ludus.js",
   "directories": {},
diff --git a/src/ludus/error.cljc b/src/ludus/error.cljc
index 4fddd3b..548087d 100644
--- a/src/ludus/error.cljc
+++ b/src/ludus/error.cljc
@@ -12,7 +12,7 @@
       		line-start (reduce (fn [len line] (+ len (count line))) (count lines-before) lines-before)
       		from-start (- start line-start)
       		underline-length (count lexeme)
-      		padding (string/join (take (+ prefix from-start) (repeat " ")))
+      		padding (string/join (take (+ prefix from-start) (repeat "-")))
       		underline (string/join (take underline-length (repeat "^")))]
   		(apply str padding underline)
   		))
@@ -31,3 +31,9 @@
   		(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)
+  		))
diff --git a/src/ludus/interpreter.cljc b/src/ludus/interpreter.cljc
index 59e24cd..516d69b 100644
--- a/src/ludus/interpreter.cljc
+++ b/src/ludus/interpreter.cljc
@@ -302,7 +302,7 @@
         (if (= match-value value)
           {:success true :ctx {}}
           {:success false
-           :reason (str "No match: Could not match " (show/show-pattern match-value) " with " (show/show value))}))
+           :reason (str "No match: Could not match " (show/show-pattern pattern) " with " (show/show value))}))
 
       :word
       (let [word (-> pattern :data first)]
@@ -965,10 +965,10 @@
       ;(println "Running source: " source)
       (interpret-ast parsed base-ctx)
       (catch #?(:clj Throwable :cljs js/Object) e
-        (println "Ludus panicked!")
-        (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))
+        ;(println "Ludus panicked!")
+        ;(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))
         ;(pp/pprint (ex-data e))
         ;(throw e)
         {::data/error true 
diff --git a/src/ludus/node.cljc b/src/ludus/node.cljc
index f5a8fdd..163e2ef 100644
--- a/src/ludus/node.cljc
+++ b/src/ludus/node.cljc
@@ -51,7 +51,7 @@
      	(clean-out {:errors [(error/parse-error source user_parsed)]})
 
      	(::data/error user_result)
-     	(clean-out {:errors [user_result]})
+     	(clean-out (assoc (ld->clj post_result) :errors [(error/run-error source user_result)]))
 
      	:else
      	(clean-out clj_result)
diff --git a/src/ludus/prelude.ld b/src/ludus/prelude.ld
index 476394e..1c02570 100644
--- a/src/ludus/prelude.ld
+++ b/src/ludus/prelude.ld
@@ -256,7 +256,10 @@ fn string {
 	"Converts a value to a string by using `show`. If it is a string, returns it unharmed. Use this to build up strings of differen kinds of values."
 	(x as :string) -> x
 	(x) -> show (x)
-	(x, ...xs) -> fold (string, xs, x)
+	(x, ...xs) -> loop (x, xs) with {
+		(out, [x]) -> concat (out, show(x))
+		(out, [x, ...xs]) -> recur (concat (out, show (x)), xs)
+	}
 }
 
 fn join {
@@ -887,31 +890,32 @@ fn make_line ((x1, y1), (x2, y2)) -> (:line, x1, y1, x2, y2)
 
 let turtle_radius = 20
 
-let turtle_angle = 0.375
+let turtle_angle = 0.385
 
-let turtle_color = (150, 150, 150, 200)
+let turtle_color = (255, 255, 255, 150)
 
 fn render_turtle! () -> {
 	let state = do turtle_states > deref > last
 	if state :visible?
 		then {
-			add_call! ((:push))	
 			let (r, g, b, a) = turtle_color
 			add_call! ((:fill, r, g, b, a))
-			add_call! ((:noStroke))
 			let #{heading, :position (x, y)} = state
-			add_call! ((:translate, x, y))
-			add_call! ((:rotate, turn/rad (add (heading, 0.25))))
-			add_call! ((:beginShape))
-			let head_unit = heading/vector (heading)
-			let first = mult (head_unit, turtle_radius)
+			let first = mult ((0, 1), turtle_radius)
 			let (x1, y1) = first
 			let (x2, y2) = rotate (first, turtle_angle)
 			let (x3, y3) = rotate (first, neg (turtle_angle))
+			add_call! ((:push))	
+			add_call! ((:translate, x, y))
+			add_call! ((:rotate, turn/rad (heading)))
+			add_call! ((:noStroke))
+			add_call! ((:beginShape))
 			add_call! ((:vertex, x1, y1))
 			add_call! ((:vertex, x2, y2))
 			add_call! ((:vertex, x3, y3))
 			add_call! ((:endShape))
+			add_call! ((:stroke, 0))
+			add_call! ((:line, 0, 0, x1, y1))
 			add_call! ((:pop))
 			:ok
 		}
@@ -1046,8 +1050,8 @@ fn apply_command {
 		(:goto, (x, y)) -> assoc (state, :position, (x, y))
 		(:home) -> assoc (state, :position, (0, 0))
 		(:clear) -> assoc (state, :position, (0, 0))
-		(:right, turns) -> update (state, :heading, sub (_, turns))
-		(:left, turns) -> update (state, :heading, add (_, turns))
+		(:right, turns) -> update (state, :heading, add (_, turns))
+		(:left, turns) -> update (state, :heading, sub (_, turns))
 		(:forward, steps) -> {
 			let #{heading, position} = state
 			let unit = heading/vector (heading)
@@ -1208,6 +1212,7 @@ ns prelude {
 	penup!, pu!
 	pendown!, pd!
 	pencolor!, pc!
+	background!, bg!
 	penwidth!, pw!
 	home!, clear!, goto!,
 	heading, position, pendown?
diff --git a/src/ludus/show.cljc b/src/ludus/show.cljc
index 064fe7c..0ac637a 100644
--- a/src/ludus/show.cljc
+++ b/src/ludus/show.cljc
@@ -1,6 +1,10 @@
 (ns ludus.show
   (:require
     [ludus.data :as data]
+    ; [ludus.scanner :as s]
+    ; [ludus.parser :as p]
+    ; [ludus.grammar :as g]
+    ; [ludus.interpreter :as i]
     [clojure.pprint :as pp]))
 
 (declare show show-linear show-keyed)
@@ -75,7 +79,7 @@
 
     :else "else"
 
-    (:word :number :keyword :true :false :nil :string) (-> pattern :data first)
+    (:word :number :keyword :true :false :nil :string) (-> pattern :data first show)
 
     :typed
     (let [word (-> pattern :data first :data first)
@@ -100,3 +104,11 @@
     :struct-pattern (show-coll-pattern pattern ["@{" "}"])
 
     ))
+
+(comment
+  (def source "let 1 = 0")
+  (def tokens (-> source s/scan :tokens))
+  (def ast (p/apply-parser g/script tokens))
+  (println (i/prettify-ast ast))
+  (println (-> ast :data first :data first show-pattern))
+  )