diff --git a/src/cg/06-inspector.cg b/src/cg/06-inspector.cg
index 82bd87b..c88b2a1 100644
--- a/src/cg/06-inspector.cg
+++ b/src/cg/06-inspector.cg
@@ -1,5 +1,5 @@
 inspector = config \
-  val = eval config.name;
+  val = eval! config.name;
 
   reflected = val
     | Value v \ reflect v
diff --git a/src/cg/06-tree.cg b/src/cg/06-tree.cg
index c327f85..504a059 100644
--- a/src/cg/06-tree.cg
+++ b/src/cg/06-tree.cg
@@ -75,7 +75,7 @@ treeNode = config \
   isExp = contains config.path config.expanded;
 
   onSubmit = text \ (
-    (eval text)
+    (eval! text)
     | Value v \ batch [rebindAt config.path v, config.onDoneEditing {}]
     | _ \ config.onDoneEditing {});
 
@@ -204,7 +204,7 @@ tree = config \
     view = state emit \
       onToggle = path \ emit (Toggle path);
       onEditLeaf = path \
-        _ = debug "onEditLeaf" path;
+        _ = debug! "onEditLeaf" path;
         emit (EditLeaf path);
       onDoneEditing = _ \ emit DoneEditing;
       totalH = treeNodeHeight config.value config.path state.expanded;
diff --git a/src/cg/10-os.cg b/src/cg/10-os.cg
index 228bc62..ff43086 100644
--- a/src/cg/10-os.cg
+++ b/src/cg/10-os.cg
@@ -174,14 +174,14 @@ os =
     | None \ openWindow title content;
 
   onSelect = input \
-    result = eval input;
+    result = eval! input;
     result
     | Defined name \ openOrFocus name (size \ inspector { name = name, w = size.w, h = size.h })
 
     | Value v \ (getSource input == ""
       | True \ openOrFocus input (_ \ ui.text { content = show v, color = "white" })
       | False \ openOrFocus input (size \ inspector { name = input, w = size.w, h = size.h }))
-    | Err msg \ (_ = debug "Error" msg; noOp);
+    | Err msg \ (_ = debug! "Error" msg; noOp);
 
   handleFocusLeftEvent = state \
     newIndex = max 0 (osState.wm.focusedIndex - 1);
diff --git a/src/runtime-js.ts b/src/runtime-js.ts
index 1a77e67..e7e96b1 100644
--- a/src/runtime-js.ts
+++ b/src/runtime-js.ts
@@ -82,7 +82,7 @@ export const _rt = {
     join: (delim: string) => (xs: string[]) => xs.join(delim),
     split: (delim: string) => (xs: string) => xs.split(delim),
     slice: (s: string | any[]) => (start: number) => (end: number) => s.slice(start, end),
-    debug: (label: string) => (value: any) => { console.log(label, value); return value; },
+    "debug!": (label: string) => (value: any) => { console.log(label, value); return value; },
     fuzzyMatch: (query: string) => (target: string) => {
         const q = query.toLowerCase();
         const t = target.toLowerCase();
@@ -101,7 +101,7 @@ export const _rt = {
         const printed = prettyPrint(ast);
         return printed;
     },
-    saveImage: () => {
+    "saveImage!": () => {
         const saved: Record<string, string> = {};
         for (const [name, ast] of definitions) {
             const source = prettyPrint({ kind: 'definition', name, body: ast });
@@ -137,7 +137,7 @@ export const _rt = {
 
         return { _tag: 'Rebind', _0: name, _1: path, _2: value };
     },
-    undefine: (name: string) => {
+    "undefine": (name: string) => {
         delete store[name];
         definitions.delete(name);
         dependencies.delete(name);
@@ -171,7 +171,7 @@ export const _rt = {
         return { _tag: 'NoneValue' };
     },
 
-    eval: (code: string) => {
+    "eval!": (code: string) => {
         const trimmed = code.trim();
 
         // is it a definition