diff --git a/src/cg/03-ui-components.cg b/src/cg/03-ui-components.cg
index 5070286..ecb0916 100644
--- a/src/cg/03-ui-components.cg
+++ b/src/cg/03-ui-components.cg
@@ -1,45 +1,45 @@
 centerH = parentW child \
-  childW = (measure child).width;
-  Positioned { x = (parentW - childW) / 2, y = 0, child = child };
+  childW = (ui.measure child).width;
+  ui.positioned { x = (parentW - childW) / 2, y = 0, child = child };
 
 centerV = parentH child \
-  childH = (measure child).height;
-  Positioned { y = (parentH - childH) / 2, x = 0, child = child };
+  childH = (ui.measure child).height;
+  ui.positioned { y = (parentH - childH) / 2, x = 0, child = child };
 
 center = parentW parentH child \
-  childSize = measure child;
-  Positioned { x = (parentW - childSize.width) / 2, y = (parentH - childSize.height) / 2, child = child };
+  childSize = ui.measure child;
+  ui.positioned { x = (parentW - childSize.width) / 2, y = (parentH - childSize.height) / 2, child = child };
 
-# button : Record -> UI
+# button : Record -> ui
 button = config \
-  Clickable {
+  ui.clickable {
     event = config.event,
-    child = Stack {
+    child = ui.stack {
       children = [
-        Rect { w = 100, h = 40, color = "#eee" },
-        Text { content = config.label, x = 10, y = 25, color = "#222" }
+        ui.rect { w = 100, h = 40, color = "#eee" },
+        ui.text { content = config.label, x = 10, y = 25, color = "#222" }
       ]
     }
   };
 
-box = config \ Stack {
+box = config \ ui.stack {
   children = [
     # background
-    Rect { w = config.w, h = config.h, color = config.color },
+    ui.rect { w = config.w, h = config.h, color = config.color },
     # top border
-    Rect { w = config.w, h = config.borderTop, color = config.borderColor },
+    ui.rect { w = config.w, h = config.borderTop, color = config.borderColor },
     # bottom border
-    Positioned { x = 0, y = config.h - config.borderBottom, child =
-      Rect { w = config.w, h = config.borderBottom, color = config.borderColor }
+    ui.positioned { x = 0, y = config.h - config.borderBottom, child =
+      ui.rect { w = config.w, h = config.borderBottom, color = config.borderColor }
     },
     # left border
-    Rect { w = config.borderLeft, h = config.h, color = config.borderColor },
+    ui.rect { w = config.borderLeft, h = config.h, color = config.borderColor },
     # right border
-    Positioned { x = config.w - config.borderRight, y = 0, child =
-      Rect { w = config.borderRight, h = config.h, color = config.borderColor }
+    ui.positioned { x = config.w - config.borderRight, y = 0, child =
+      ui.rect { w = config.borderRight, h = config.h, color = config.borderColor }
     },
     # content
-    Positioned { x = config.paddingLeft, y = config.paddingTop, child = config.child }
+    ui.positioned { x = config.paddingLeft, y = config.paddingTop, child = config.child }
   ]};
 
 insertChar = text pos char \
@@ -57,7 +57,7 @@ deleteChar = text pos \
 
 calcScrollOffset = text cursorPos scrollOffset inputWidth \
   textBeforeCursor = slice text 0 cursorPos;
-  cursorX = measureText textBeforeCursor;
+  cursorX = ui.measureText textBeforeCursor;
   (cursorX < scrollOffset
   | True \ max 0 (cursorX - 20)
   | False \
@@ -69,8 +69,8 @@ findPosHelper = text targetX index \
   (index >= len text)
   | True \ len text
   | False \ (
-    widthSoFar = measureText (slice text 0 index);
-    widthNext = measureText (slice text 0 (index + 1));
+    widthSoFar = ui.measureText (slice text 0 index);
+    widthNext = ui.measureText (slice text 0 (index + 1));
     midpoint = (widthSoFar + widthNext) / 2;
     (targetX < midpoint
     | True \ index
@@ -81,7 +81,7 @@ findCursorPos = text clickX scrollOffset inputPadding \
   adjustedX = clickX + scrollOffset - inputPadding;
   findPosHelper text adjustedX 0;
 
-textInput = config \ Stateful {
+textInput = config \ ui.stateful {
   key = config.key,
   focusable = True,
 
@@ -133,29 +133,29 @@ textInput = config \ Stateful {
 
   view = state \
     textBeforeCursor = slice state.text 0 state.cursorPos;
-    cursorX = measureText textBeforeCursor;
+    cursorX = ui.measureText textBeforeCursor;
     padding = 8;
 
-    Clip {
+    ui.clip {
       w = config.w,
       h = config.h,
-      child = Stack {
+      child = ui.stack {
         children = [
-          Rect { w = config.w, h = config.h, color = config.backgroundColor, radius = 0 },
+          ui.rect { w = config.w, h = config.h, color = config.backgroundColor, radius = 0 },
 
-          Positioned {
+          ui.positioned {
             x = 8 - state.scrollOffset,
             y = 0,
-            child = Positioned { x = 0, y = 12, child = Text { content = state.text, color = config.color } }
+            child = ui.positioned { x = 0, y = 12, child = ui.text { content = state.text, color = config.color } }
           },
 
           (state.focused
-          | True \ Positioned {
+          | True \ ui.positioned {
             x = 8 + cursorX - state.scrollOffset,
             y = 8,
-            child = Rect { w = 2, h = 24, color = config.color }
+            child = ui.rect { w = 2, h = 24, color = config.color }
           }
-          | _ \ Rect { w = 0, h = 0, color = "transparent" })
+          | _ \ ui.rect { w = 0, h = 0, color = "transparent" })
         ]
       }
     }
diff --git a/src/cg/05-palette.cg b/src/cg/05-palette.cg
index b5d1b80..d21a390 100644
--- a/src/cg/05-palette.cg
+++ b/src/cg/05-palette.cg
@@ -5,42 +5,42 @@ palette = config \
 
   results = take 10 (config.search config.state.query);
 
-  padding = 0;
+  dialogPadding = 0;
 
   textInputHeight = 40;
-  contentWidth = windowWidth - (padding * 2);
-  contentHeight = windowHeight - (padding * 2);
+  contentWidth = windowWidth - (dialogPadding * 2);
+  contentHeight = windowHeight - (dialogPadding * 2);
   listHeight = contentHeight - 40;
 
   paletteRow = config \
     color = (config.selected | True \ "rgba(255,255,255,0.2)" | False \ "transparent");
 
-    Clickable {
+    ui.clickable {
       event = config.onClick,
-      child = Stack {
+      child = ui.stack {
         children = [
-          Rect { w = config.w, h = config.h, color = color },
+          ui.rect { w = config.w, h = config.h, color = color },
           centerV config.h (
-            Positioned {
+            ui.positioned {
               x = 10,
               y = 10,
-              child = Text { content = config.child, color = "white" }
+              child = ui.text { content = config.child, color = "white" }
             }
           )
         ]
       }
     };
 
-  Positioned {
+  ui.positioned {
     x = (config.viewport.width - windowWidth) / 2,
     y = (config.viewport.height - windowHeight) / 2,
 
-    child = Stack {
+    child = ui.stack {
       children = [
-        Rect { w = windowWidth, h = windowHeight, color = "#063351", radius = 0, strokeWidth = 1, strokeColor = "#1A5F80" },
-        Padding {
-          amount = padding,
-          child = Column {
+        ui.rect { w = windowWidth, h = windowHeight, color = "#063351", radius = 0, strokeWidth = 1, strokeColor = "#1A5F80" },
+        ui.padding {
+          amount = dialogPadding,
+          child = ui.column {
             gap = 0,
             children = [
               textInput {
@@ -51,17 +51,17 @@ palette = config \
                 backgroundColor = "rgba(0,0,0,0.2)",
                 w = contentWidth,
                 h = textInputHeight,
-                onChange = text \ Batch [config.state.query := text, config.state.focusedIndex := 0],
+                onChange = text \ batch [config.state.query := text, config.state.focusedIndex := 0],
                 onKeyDown = key \ key
                   | ArrowUp \ config.state.focusedIndex := max 0 (config.state.focusedIndex - 1)
                   | ArrowDown \ config.state.focusedIndex := (config.state.focusedIndex + 1)
                   | Enter \ (\ config.onSelect (unwrapOr "" (nth config.state.focusedIndex results)))
-                  | _ \ NoOp
+                  | _ \ noOp
               },
-              Clip {
+              ui.clip {
                 w = contentWidth,
                 h = listHeight,
-                child = Column {
+                child = ui.column {
                   gap = 1,
                   children = mapWithIndex (t i \ paletteRow {
                     child = t,
diff --git a/src/cg/10-os.cg b/src/cg/10-os.cg
index 1fbe5e8..c77991d 100644
--- a/src/cg/10-os.cg
+++ b/src/cg/10-os.cg
@@ -1,5 +1,6 @@
 osState = {
   palette = {
+    visible = True,
     query = "",
     focusedIndex = 0,
   },
@@ -11,15 +12,17 @@ update = state event \ event
   | _ \ state;
 
 view = state viewport \
-  Stack {
+  ui.stack {
     children = [
-      Rect { w = viewport.width, h = viewport.height, color = "#012" },
-      palette {
-        state = osState.palette,
-        search = storeSearch,
-        onSelect = item \ (debug "selected" item),
-        viewport = viewport,
-      }
+      ui.rect { w = viewport.width, h = viewport.height, color = "#012" },
+      osState.palette.visible
+      | True \ palette {
+          state = osState.palette,
+          search = storeSearch,
+          onSelect = item \ (debug "selected" item),
+          viewport = viewport,
+        }
+      | False \ text { content = "" }
     ]
   };
 
diff --git a/src/compiler.ts b/src/compiler.ts
index 143869f..68f20b0 100644
--- a/src/compiler.ts
+++ b/src/compiler.ts
@@ -18,7 +18,7 @@ export function compile(ast: AST): string {
             return sanitize(ast.name);
 
         case 'lambda':
-            const params = ast.params.map(sanitize).join(') => (');
+            const params = ast.params.map(sanitizeName).join(') => (');
             return `Object.assign((${params}) => ${compile(ast.body)}, { _ast: (${JSON.stringify(ast)}) })`;
 
         case 'apply':
@@ -36,7 +36,7 @@ export function compile(ast: AST): string {
 
         case 'record': {
             const fields = Object.entries(ast.fields)
-                .map(([k, v]) => `${sanitize(k)}: ${compile(v)}`);
+                .map(([k, v]) => `${sanitizeName(k)}: ${compile(v)}`);
             return `({${fields.join(', ')}})`;
         }
 
@@ -48,15 +48,15 @@ export function compile(ast: AST): string {
         }
 
         case 'record-access':
-            return `${compile(ast.record)}.${sanitize(ast.field)}`;
+            return `${compile(ast.record)}.${sanitizeName(ast.field)}`;
 
         case 'record-update':
             const updates = Object.entries(ast.updates)
-                .map(([k, v]) => `${sanitize(k)}: ${compile(v)}`);
+                .map(([k, v]) => `${sanitizeName(k)}: ${compile(v)}`);
             return `({...${compile(ast.record)}, ${updates.join(', ')}})`;
 
         case 'let':
-            return `((${sanitize(ast.name)}) =>
+            return `((${sanitizeName(ast.name)}) =>
                      ${compile(ast.body)})(${compile(ast.value)})`;
 
         case 'match':
@@ -98,9 +98,13 @@ function sanitize(name: string): string {
 
     if (ops[name]) return ops[name];
 
-    const natives = ['measure', 'measureText', 'storeSearch', 'getSource', 'debug', 'len', 'slice', 'str', 'redefine'];
+    const natives = ['measure', 'measureText', 'storeSearch', 'getSource', 'debug', 'len', 'slice', 'str', 'redefine', 'stateful', 'batch', 'noOp', 'rerender', 'focus', 'ui'];
     if (natives.includes(name)) return `_rt.${name}`;
 
+    return sanitizeName(name);
+}
+
+function sanitizeName(name: string): string {
     const reserved = [
         'default','class','function','return','const','let','var',
         'if','else','switch','case','for','while','do','break',
@@ -138,7 +142,7 @@ function compilePattern(pattern: Pattern, expr: string): { condition: string, bi
             return { condition: 'true', bindings: [] };
 
         case 'var':
-            return { condition: 'true', bindings: [`${sanitize(pattern.name)} = ${expr}`] };
+            return { condition: 'true', bindings: [`${sanitizeName(pattern.name)} = ${expr}`] };
 
         case 'literal':
             return { condition: `${expr} === ${JSON.stringify(pattern.value)}`, bindings: [] };
diff --git a/src/runtime-js.ts b/src/runtime-js.ts
index 6c3e3a1..531583e 100644
--- a/src/runtime-js.ts
+++ b/src/runtime-js.ts
@@ -22,19 +22,39 @@ export const _rt = {
     gte: (a: any) => (b: any) => ({ _tag: a >= b ? 'True' : 'False' }),
     lte: (a: any) => (b: any) => ({ _tag: a <= b ? 'True' : 'False' }),
 
+    ui: {
+        rect: (config: any) => ({ _kind: 'rect', ...config }),
+        text: (config: any) => ({ _kind: 'text', ...config }),
+        stack: (config: any) => ({ _kind: 'stack', ...config }),
+        row: (config: any) => ({ _kind: 'row', ...config }),
+        column: (config: any) => ({ _kind: 'column', ...config }),
+        padding: (config: any) => ({ _kind: 'padding', ...config }),
+        positioned: (config: any) => ({ _kind: 'positioned', ...config }),
+        clickable: (config: any) => ({ _kind: 'clickable', ...config }),
+        clip: (config: any) => ({ _kind: 'clip', ...config }),
+        opacity: (config: any) => ({ _kind: 'opacity', ...config }),
+        stateful: (config: any) => ({ _kind: 'stateful', ...config }),
+        measure: (config: any) => ({ _kind: 'measure', ...config }),
+        measureText: (text: string) => {
+            const canvas = document.createElement('canvas');
+            const ctx = canvas.getContext('2d');
+            if (ctx) {
+                ctx.font = '16px "SF Mono", "Monaco", "Menlo", monospace';
+                return Math.floor(ctx.measureText(text).width);
+            }
+            return text.length * 10; // fallback
+        },
+    },
+
+    batch: (events: any[]) => ({ _tag: 'Batch', _0: events }),
+    noOp: { _tag: 'NoOp' },
+    rerender: { _tag: 'Rerender' },
+    focus: (key: string) => ({ _tag: 'Focus', _0: key }),
+
     len: (list: any[]) => list.length,
     str: (x: any) => String(x),
     slice: (s: string | any[]) => (start: number) => (end: number) => s.slice(start, end),
     debug: (label: string) => (value: any) => { console.log(label, value); return value; },
-    measureText: (text: string) => {
-        const canvas = document.createElement('canvas');
-        const ctx = canvas.getContext('2d');
-        if (ctx) {
-            ctx.font = '16px "SF Mono", "Monaco", "Menlo", monospace';
-            return Math.floor(ctx.measureText(text).width);
-        }
-        return text.length * 10; // fallback
-    },
     fuzzyMatch: (query: string) => (target: string) => {
         const q = query.toLowerCase();
         const t = target.toLowerCase();
@@ -69,11 +89,11 @@ export const _rt = {
         }
     },
     measure: (ui: any): { width: number, height: number } => {
-        switch (ui._tag) {
-            case 'Rect': return { width: ui.w, height: ui.h };
-            case 'Text': return { width: ui.content.length * 10, height: 20 }; // TODO
-            case 'Clip': return { width: ui.w, height: ui.h };
-            case 'Row': {
+        switch (ui._kind) {
+            case 'rect': return { width: ui.w, height: ui.h };
+            case 'text': return { width: ui.content.length * 10, height: 20 }; // TODO
+            case 'clip': return { width: ui.w, height: ui.h };
+            case 'row': {
                 let totalWidth = 0;
                 let maxHeight = 0;
                 for (const child of ui.children) {
@@ -85,7 +105,7 @@ export const _rt = {
                 return { width: totalWidth, height: maxHeight };
             }
 
-            case 'Column': {
+            case 'column': {
                 let totalHeight = 0;
                 let maxWidth = 0;
                 for (const child of ui.children) {
@@ -97,7 +117,7 @@ export const _rt = {
                 return { width: maxWidth, height: totalHeight };
             }
 
-            case 'Padding': {
+            case 'padding': {
                 const childSize = _rt.measure(ui.child);
                 return {
                     width: childSize.width + ui.amount * 2,
@@ -105,7 +125,7 @@ export const _rt = {
                 }
             }
 
-            case 'Stack': {
+            case 'stack': {
                 let maxWidth = 0;
                 let maxHeight = 0;
                 for (const child of ui.children) {
@@ -117,9 +137,9 @@ export const _rt = {
                 return { width: maxWidth, height: maxHeight };
             }
 
-            case 'Clickable':
-            case 'Opacity':
-            case 'Positioned':
+            case 'clickable':
+            case 'opacity':
+            case 'positioned':
                 return _rt.measure(ui.child);
 
             default:
diff --git a/src/valueToUI-compiled.ts b/src/valueToUI-compiled.ts
index 377bfa4..a7965a3 100644
--- a/src/valueToUI-compiled.ts
+++ b/src/valueToUI-compiled.ts
@@ -1,11 +1,11 @@
 // import type { UIValue } from './types'
 
 export function valueToUI(value: any): any {
-    if (!value || !value._tag)
+    if (!value || !value._kind)
         throw new Error(`Expected UI constructor, got: ${JSON.stringify(value)}`);
 
-    switch(value._tag) {
-        case 'Rect':
+    switch(value._kind) {
+        case 'rect':
             return {
                 kind: 'rect',
                 w: value.w,
@@ -16,34 +16,34 @@ export function valueToUI(value: any): any {
                 strokeColor: value.strokeColor,
             };
 
-        case 'Text':
+        case 'text':
             return {
                 kind: 'text',
                 content: value.content,
                 color: value.color,
             };
 
-        case 'Row':
+        case 'row':
             return {
                 kind: 'row',
                 gap: value.gap || 0,
                 children: value.children.map(valueToUI),
             };
 
-        case 'Column':
+        case 'column':
             return {
                 kind: 'column',
                 gap: value.gap || 0,
                 children: value.children.map(valueToUI),
             };
 
-        case 'Stack':
+        case 'stack':
             return {
                 kind: 'stack',
                 children: value.children.map(valueToUI),
             };
 
-        case 'Positioned':
+        case 'positioned':
             return {
                 kind: 'positioned',
                 x: value.x || 0,
@@ -51,21 +51,21 @@ export function valueToUI(value: any): any {
                 child: valueToUI(value.child),
             };
 
-        case 'Padding':
+        case 'padding':
             return {
                 kind: 'padding',
                 amount: value.amount || 0,
                 child: valueToUI(value.child),
             };
 
-        case 'Clickable':
+        case 'clickable':
             return {
                 kind: 'clickable',
                 event: value.event,
                 child: valueToUI(value.child),
             };
 
-        case 'Clip':
+        case 'clip':
             return {
                 kind: 'clip',
                 w: value.w,
@@ -73,14 +73,14 @@ export function valueToUI(value: any): any {
                 child: valueToUI(value.child),
             };
 
-        case 'Opacity':
+        case 'opacity':
             return {
                 kind: 'opacity',
                 opacity: value.opacity,
                 child: valueToUI(value.child),
             };
 
-        case 'Stateful':
+        case 'stateful':
             return {
                 kind: 'stateful',
                 key: value.key,