diff --git a/docs/examples/baconjs/index.js b/docs/examples/baconjs/index.js
new file mode 100644
index 0000000..0b84f10
--- /dev/null
+++ b/docs/examples/baconjs/index.js
@@ -0,0 +1,24 @@
+// external
+import {} from 'https://unpkg.com/jquery'
+// external
+import {fromEvent} from 'https://unpkg.com/baconjs?module'
+
+const upEl = globalThis.document.createElement('button')
+const downEl = globalThis.document.createElement('button')
+const counterEl = globalThis.document.createElement('div')
+
+globalThis.document.body.appendChild(upEl)
+globalThis.document.body.appendChild(downEl)
+globalThis.document.body.appendChild(counterEl)
+
+const up = fromEvent(upEl, 'click');
+const down = fromEvent(downEl, 'click');
+
+const counter =
+  // map up to 1, down to -1
+  up.map(1).merge(down.map(-1))
+  // accumulate sum
+    .scan(0, (x,y) => x + y);
+
+// assign observable value to jQuery property text
+counter.onValue(text => Object.assign(counterEl, {innerText: text}));
diff --git a/src/editor/value_explorer.js b/src/editor/value_explorer.js
index 732b4e5..0bc684b 100644
--- a/src/editor/value_explorer.js
+++ b/src/editor/value_explorer.js
@@ -6,6 +6,10 @@
 
 import {el, stringify, scrollIntoViewIfNeeded} from './domutils.js'
 
+
+// TODO only test for globalThis.<GlobalObject> because we only eval code in
+// another window
+
 const has_custom_toString = object =>
   object.toString != globalThis.run_window.Object.prototype.toString
   &&
@@ -16,6 +20,11 @@ const isError = object =>
   ||
   object instanceof globalThis.run_window.Error
 
+const isPromise = object =>
+  object instanceof Promise
+  ||
+  object instanceof globalThis.run_window.Promise
+
 const displayed_entries = object => {
   if(Array.isArray(object)) {
     return object.map((v, i) => [i, v])
@@ -39,6 +48,8 @@ export const stringify_for_header = v => {
   } else if(type == 'function') {
     // TODO clickable link, 'fn', cursive
     return 'fn ' + v.name
+  } else if (isPromise(v)) {
+    return 'Promise<>'
   } else if(isError(v)) {
     return v.toString()
   } else if(type == 'object') {
@@ -70,7 +81,9 @@ export const header = object => {
   } else if(object == null) {
     return 'null'
   } else if(typeof(object) == 'object') {
-    if(isError(object)) {
+    if(isPromise(object)) {
+      return 'Promise<>'
+    } else if(isError(object)) {
       return object.toString()
     } else if(Array.isArray(object)) {
       return '['
diff --git a/src/effects.js b/src/effects.js
index 991cf9b..df25651 100644
--- a/src/effects.js
+++ b/src/effects.js
@@ -8,6 +8,7 @@ import {
 import {current_cursor_position} from './calltree.js'
 import {FLAGS} from './feature_flags.js'
 import {exec, FILES_ROOT} from './index.js'
+import {unwrap_settled_promises} from './unwrap_promises.js'
 
 // Imports in the context of `run_window`, so global variables in loaded
 // modules refer to that window's context 
@@ -128,7 +129,7 @@ export const render_initial_state = (ui, state) => {
   ui.editor.switch_session(state.current_module)
 }
 
-export const render_common_side_effects = (prev, next, command, ui) => {
+export const render_common_side_effects = async (prev, next, command, ui) => {
   if(
     prev.project_dir != next.project_dir 
     || 
@@ -187,6 +188,8 @@ export const render_common_side_effects = (prev, next, command, ui) => {
 
   } else {
 
+    await unwrap_settled_promises(next.calltree)
+
     if(
       prev.calltree == null
       ||
diff --git a/src/eval.js b/src/eval.js
index 1028ac9..bed1b17 100644
--- a/src/eval.js
+++ b/src/eval.js
@@ -73,7 +73,7 @@ const codegen_function_expr = (node, cxt) => {
 
   const args = node.function_args.children.map(do_codegen).join(',')
 
-  const call = `(${args}) => ` + (
+  const call = (node.is_async ? 'async ' : '') + `(${args}) => ` + (
     (node.body.type == 'do')
     ? '{' + do_codegen(node.body) + '}'
     : '(' + do_codegen(node.body) + ')'
@@ -384,7 +384,17 @@ export const eval_modules = (
         try {
           value = fn(...args)
           ok = true
-          return value
+          return value instanceof Promise.Original 
+            ? value
+                .then(v => {
+                  value.status = {ok: true, value: v}
+                  return v
+                })
+                .catch(e => {
+                  value.status = {ok: false, error: e}
+                  throw e
+                })
+            : value
         } catch(_error) {
           ok = false
           error = _error
@@ -917,6 +927,10 @@ const do_eval_frame_expr = (node, scope, callsleft) => {
         value = typeof(expr.result.value)
       } else if(node.operator == '-') {
         value = - expr.result.value
+      } else if(node.operator == 'await') {
+        log('expr', expr.result.value.status)
+        value = expr.result.value
+        //throw new Error('not implemented')
       } else {
         throw new Error('unknown op')
       }
diff --git a/src/find_definitions.js b/src/find_definitions.js
index 86f9521..5ce41d1 100644
--- a/src/find_definitions.js
+++ b/src/find_definitions.js
@@ -243,6 +243,7 @@ code analysis:
 - cannot import names that are not exported from modules
 - module can be imported either as external or regular
 - cannot return from modules (even inside toplevel if statements)
+- await only in async fns
 */
 export const analyze = (node, is_toplevel = true) => {
   // TODO remove
diff --git a/src/parse_js.js b/src/parse_js.js
index 4bc78c3..59d8b83 100644
--- a/src/parse_js.js
+++ b/src/parse_js.js
@@ -908,6 +908,8 @@ const object_literal =
 const function_expr =
   if_ok(
     seq([
+      optional(literal('async')),
+
       either(
         // arguments inside braces
         list_destructuring(['(', ')'], 'function_args'),
@@ -934,7 +936,7 @@ const function_expr =
     ]),
 
     ({value, ...node}) => {
-      const [args, _, body] = value
+      const [is_async, args, _, body] = value
       const function_args = args.type == 'identifier'
         ? {
             ...args, 
@@ -950,6 +952,7 @@ const function_expr =
       return {
         ...node,
         type: 'function_expr',
+        is_async: is_async != null,
         body,
         children: [function_args, body]
       }
@@ -1029,6 +1032,7 @@ const expr =
     unary('!'),
     unary('-'),
     unary('typeof'),
+    unary('await'),
     binary(['**']),
     binary(['*','/','%']),
     binary(['+','-']),
diff --git a/src/patch_promise.js b/src/patch_promise.js
new file mode 100644
index 0000000..1c1a4b6
--- /dev/null
+++ b/src/patch_promise.js
@@ -0,0 +1,40 @@
+export const patch_promise = window => {
+
+  // TODO check that it is not already patched
+  if(window.Promise.Original != null) {
+    throw new Error('already patched')
+  }
+
+  class PromiseWithStatus extends Promise {
+    constructor(fn) {
+      let status 
+      let is_constructor_finished = false
+      super(
+        (resolve, reject) => {
+          fn(
+            (value) => {
+              status = {ok: true, value}
+              if(is_constructor_finished) {
+                this.status = status
+              }
+              resolve(value)
+            },
+            (error) => {
+              status = {ok: false, error}
+              if(is_constructor_finished) {
+                this.status = status
+              }
+              reject(error)
+            },
+          )
+        }
+      )
+      is_constructor_finished = true
+      this.status = status
+    }
+  }
+
+  PromiseWithStatus.Original = Promise
+
+  window.Promise = PromiseWithStatus
+}
diff --git a/src/unwrap_promises.js b/src/unwrap_promises.js
new file mode 100644
index 0000000..3f140aa
--- /dev/null
+++ b/src/unwrap_promises.js
@@ -0,0 +1,59 @@
+export const unwrap_settled_promises = calltree => {
+  let is_finished = false
+
+  const unwrap = call => {
+    // TODO use run_window.Promise
+
+    if(!call.ok) {
+      return
+    }
+
+    if(call.value instanceof Promise) {
+      call.value
+        .then(value => {
+          if(is_finished) {
+            return
+          }
+          call.unwrapped_value = {ok: true, value}
+        })
+        .catch(error => {
+          if(is_finished) {
+            return
+          }
+          call.unwrapped_value = {ok: false, error}
+        })
+    }
+  }
+
+  const unwrap_tree = call => {
+    unwrap(call)
+    if(call.children != null) {
+      for(let c of call.children) {
+        unwrap(c)
+      }
+    }
+  }
+
+  unwrap_tree(calltree)
+
+  return Promise.resolve().then(() => {
+    is_finished = true
+    return calltree
+  })
+}
+
+/*
+const delay = new Promise(resolve => setTimeout(() => resolve('123'), 1000))
+
+const tree = {
+  value: Promise.resolve('resolved'),
+  ok: true,
+  children: [
+    {value: delay, ok: true}
+  ]
+}
+
+await unwrap_settled_promises(tree)
+console.log('tree', tree)
+*/
+
diff --git a/test/test.js b/test/test.js
index d873518..afaf7d0 100644
--- a/test/test.js
+++ b/test/test.js
@@ -2588,4 +2588,16 @@ const y = x()`
     // must be discarded
     assert_equal(get_deferred_calls(result), null)
   }),
+
+  test_only('async/await', () => {
+    const code = `
+      const x = async () => 123
+      const y = async () => await x()
+      y()
+    `
+    const s = test_initial_state(code)
+    const move = COMMANDS.move_cursor(s, code.indexOf('await x()')).state
+    log('m', root_calltree_node(move).children[0].children[0].value)
+    //log(s.parse_result.modules[''])
+  }),
 ]
diff --git a/test/utils.js b/test/utils.js
index 78c2d77..796e5d9 100644
--- a/test/utils.js
+++ b/test/utils.js
@@ -2,6 +2,11 @@ import {parse, print_debug_node, load_modules} from '../src/parse_js.js'
 import {eval_tree, eval_frame} from '../src/eval.js'
 import {COMMANDS} from '../src/cmd.js'
 
+// external
+import {patch_promise} from '../src/patch_promise.js'
+
+patch_promise(globalThis)
+
 Object.assign(globalThis, {log: console.log})
 
 export const parse_modules = (entry, modules) => 
diff --git a/tt.js b/tt.js
new file mode 100644
index 0000000..879eed0
--- /dev/null
+++ b/tt.js
@@ -0,0 +1,63 @@
+const x = async () => 1
+
+const trace = fn => {
+  try {
+    const value = fn()
+    if(value instanceof Promise) {
+      return value
+        .then(v => {
+          value.status = {ok: true, value: v}
+          return v
+        })
+        .catch(e => {
+          value.status = {ok: false, error: e}
+          throw e
+        })
+    } else {
+      return value
+    }
+  } catch(e) {
+
+  } finally {
+  }
+}
+
+//trace(x)
+
+//const c = () => {
+//  return Promise.reject(1)
+//}
+//
+//const b = () => {
+//    return c()
+//      .then(value => {
+//        console.log('v', value)
+//        return value
+//      })
+//      .catch(e => {
+//        console.log('e')
+//        throw e
+//      })
+//}
+//
+//
+//try {
+//  console.log(b()/*.catch(x => 1)*/)
+//} catch(e) {
+//  console.log('error', e)
+//}
+
+const throws_p = () => {throw Promise.reject('err')}
+
+
+try {
+  await throws_p()
+} catch(e) {
+  console.log('e', e)
+  try {
+    await e
+  } catch(e2) {
+
+    console.log('e2', e2)
+  }
+}
diff --git a/x.js b/x.js
new file mode 100644
index 0000000..1088838
--- /dev/null
+++ b/x.js
@@ -0,0 +1,29 @@
+/*
+const delay = new Promise(resolve => {
+  setTimeout(resolve, 1000)
+})
+await delay
+console.log('x')
+export const x = 1
+*/
+
+const p = {then: y => y(3)}
+
+async function test() {
+  return await p
+}
+
+  // TODO remove
+  //const x = new Promise((resolve, reject) => resolve(10))
+  //const x = Promise.reject(10)
+  //const x = Promise.resolve(10)
+  //console.log('x', x.status)
+  //x.catch(e => {
+  //  console.log('x', x.status)
+  //})
+  //const x = new Promise((resolve, reject) => setTimeout(() => resolve(10), 1000))
+  //console.log('x', x.status)
+  //x.then(() => {
+  //  console.log('x', x.status)
+  //})
+console.log(await test())