diff --git a/README.md b/README.md
index 57d766f..4bc0dab 100644
--- a/README.md
+++ b/README.md
@@ -119,11 +119,11 @@ served from service workers).
 
 ## IO
 
-To provide interactive experience, Leporello.js caches calls to IO functions
-made by your app and can later replay them from cache, allowing to program by
+To provide interactive experience, Leporello.js traces calls to IO functions
+made by your app and can later replay them from trace, allowing to program by
 making small iterations on your code and instantly getting feedback.
 
-Current list of builtin functions which calls are cached is:
+Current list of builtin functions which calls are traced is:
 - `Date`
 - `Math.random()`
 - `fetch`
@@ -136,18 +136,18 @@ Current list of builtin functions which calls are cached is:
 - `setTimeout`
 - `clearTimeout`
 
-Leporello.js caches all IO calls when the code is run for the first time. Then,
+Leporello.js traces all IO calls when the code is run for the first time. Then,
 every time you edit your code, Leporello.js tries to execute it, taking results
-of IO calls from cache (it is called replay). Cached calls are stored in array.
+of IO calls from the trace (it is called replay). Traced calls are stored in array.
 While replay, when IO call is made, Leporello.js takes next call from the
 array, and checks if function and arguments are the same for current call and
-cached call. If they are the same, then Leporello.js returns cached result. To
+traced call. If they are the same, then Leporello.js returns result from the trace. To
 compare arguments for equality, Leporello.js uses deep equality comparison with
-`JSON.stringify`. Otherwise, the cache gets discarded, and Leporello.js
-executes code again, this time without cache, so the new cache array is
+`JSON.stringify`. Otherwise, the trace gets discarded, and Leporello.js
+executes code again, this time without the trace, so the new trace array is
 populated.
 
-If you want to bust cache manually, there is a button and a hotkey for this.
+If you want to discard trace manually, there is a button and a hotkey for this.
 
 ## Hotkeys
 
diff --git a/index.html b/index.html
index 4f98574..56f108d 100644
--- a/index.html
+++ b/index.html
@@ -145,7 +145,7 @@
         overflow: auto;
       }
 
-      .logs, .io_cache {
+      .logs, .io_trace {
         padding-left: 1em;
       }
 
diff --git a/src/cmd.js b/src/cmd.js
index c3659e8..fa71584 100644
--- a/src/cmd.js
+++ b/src/cmd.js
@@ -51,11 +51,11 @@ const apply_eval_result = (state, eval_result) => {
       log_position: null
     },
     modules: eval_result.modules,
-    io_cache: 
-      (eval_result.io_cache == null || eval_result.io_cache.length == 0)
-        // If new cache is empty, reuse previous cache
-        ? state.io_cache
-        : eval_result.io_cache
+    io_trace: 
+      (eval_result.io_trace == null || eval_result.io_trace.length == 0)
+        // If new trace is empty, reuse previous trace
+        ? state.io_trace
+        : eval_result.io_trace
   }
 }
 
@@ -201,7 +201,7 @@ const external_imports_loaded = (
       external_imports,
       state.on_deferred_call,
       state.calltree_changed_token,
-      state.io_cache,
+      state.io_trace,
     )
     toplevel = true
   } else {
@@ -210,7 +210,7 @@ const external_imports_loaded = (
       external_imports,
       state.on_deferred_call,
       state.calltree_changed_token,
-      state.io_cache,
+      state.io_trace,
       {index: node.index, module: state.current_module},
     )
     toplevel = false
@@ -804,8 +804,8 @@ const on_deferred_call = (state, call, calltree_changed_token, logs) => {
   }
 }
 
-const clear_io_cache = state => {
-  return run_code({...state, io_cache: null})
+const clear_io_trace = state => {
+  return run_code({...state, io_trace: null})
 }
 
 const do_load_dir = (state, dir) => {
@@ -902,6 +902,6 @@ export const COMMANDS = {
   external_imports_loaded,
   eval_modules_finished,
   on_deferred_call,
-  clear_io_cache,
+  clear_io_trace,
   calltree: calltree_commands,
 }
diff --git a/src/editor/io_cache.js b/src/editor/io_trace.js
similarity index 88%
rename from src/editor/io_cache.js
rename to src/editor/io_trace.js
index 56081af..01b97ea 100644
--- a/src/editor/io_cache.js
+++ b/src/editor/io_trace.js
@@ -2,7 +2,7 @@ import {header, stringify_for_header} from './value_explorer.js'
 import {el} from './domutils.js'
 import {has_error} from '../calltree.js'
 
-export class IO_Cache {
+export class IO_Trace {
   constructor(ui, el) {
     this.el = el
     this.ui = ui
@@ -25,7 +25,7 @@ export class IO_Cache {
     this.is_rendered = false
   }
 
-  render_io_cache(state, force) {
+  render_io_trace(state, force) {
     if(force) {
       this.is_rendered = false
     }
@@ -38,9 +38,9 @@ export class IO_Cache {
 
     this.el.innerHTML = ''
 
-    const items = state.io_cache ?? []
+    const items = state.io_trace ?? []
     // Number of items that were used during execution
-    const used_count = state.eval_cxt.io_cache_index ?? items.length
+    const used_count = state.eval_cxt.io_trace_index ?? items.length
 
     for(let i = 0; i < items.length; i++) {
       const item = items[i]
diff --git a/src/editor/ui.js b/src/editor/ui.js
index ed0fa96..56a99c3 100644
--- a/src/editor/ui.js
+++ b/src/editor/ui.js
@@ -3,7 +3,7 @@ import {Editor} from './editor.js'
 import {Files} from './files.js'
 import {CallTree} from './calltree.js'
 import {Logs} from './logs.js'
-import {IO_Cache} from './io_cache.js'
+import {IO_Trace} from './io_trace.js'
 import {el} from './domutils.js'
 
 export class UI {
@@ -36,11 +36,11 @@ export class UI {
                     href: 'javascript: void(0)',
                   }, 'Logs (F3)')
                 ),
-                this.tabs.io_cache = el('div', 'tab', 
+                this.tabs.io_trace = el('div', 'tab', 
                   el('a', {
-                    click: () => this.set_active_tab('io_cache'),
+                    click: () => this.set_active_tab('io_trace'),
                     href: 'javascript: void(0)',
-                  }, 'IO cache (F4)')
+                  }, 'IO trace (F4)')
                 ),
                 this.entrypoint_select = el('div', 'entrypoint_select')
               ),
@@ -52,8 +52,8 @@ export class UI {
                 'class': 'tab_content logs', 
                 tabindex: 0,
               }),
-              this.debugger.io_cache = el('div', {
-                'class': 'tab_content io_cache', 
+              this.debugger.io_trace = el('div', {
+                'class': 'tab_content io_trace', 
                 tabindex: 0,
               }),
             ),
@@ -87,9 +87,9 @@ export class UI {
           el('a', {
             'class': 'statusbar_action first',
             href: 'javascript: void(0)',
-            click: () => exec('clear_io_cache')
+            click: () => exec('clear_io_trace')
           },
-            'Clear IO cache (F6)'
+            'Clear IO trace (F6)'
           ),
 
           el('a', {
@@ -157,11 +157,11 @@ export class UI {
       }
 
       if(e.key == 'F4'){
-        this.set_active_tab('io_cache')
+        this.set_active_tab('io_trace')
       }
 
       if(e.key == 'F6'){
-        exec('clear_io_cache')
+        exec('clear_io_trace')
       }
 
       if(e.key == 'F7'){
@@ -177,7 +177,7 @@ export class UI {
 
     this.calltree = new CallTree(this, this.debugger.calltree)
     this.logs = new Logs(this, this.debugger.logs)
-    this.io_cache = new IO_Cache(this, this.debugger.io_cache)
+    this.io_trace = new IO_Trace(this, this.debugger.io_trace)
 
     // TODO jump to another module
     // TODO use exec
@@ -207,8 +207,8 @@ export class UI {
     Object.values(this.debugger).forEach(el => el.style.display = 'none')
     this.debugger[tab_id].style.display = 'block'
 
-    if(tab_id == 'io_cache') {
-      this.io_cache.render_io_cache(get_state(), false)
+    if(tab_id == 'io_trace') {
+      this.io_trace.render_io_trace(get_state(), false)
     }
 
     if(!skip_focus) {
@@ -306,13 +306,13 @@ export class UI {
     this.logs.render_logs(null, state.logs)
   }
 
-  render_io_cache(state) {
+  render_io_trace(state) {
     // render lazily, only if selected
-    if(this.active_tab == 'io_cache') {
-      this.io_cache.render_io_cache(state, true)
+    if(this.active_tab == 'io_trace') {
+      this.io_trace.render_io_trace(state, true)
     } else {
       // Do not render until user switch to the tab
-      this.io_cache.clear()
+      this.io_trace.clear()
     }
   }
 
@@ -367,8 +367,8 @@ export class UI {
       ['Focus console logs', 'F3'],
       ['Navigate console logs', '↑ ↓ or jk'],
       ['Leave console logs', 'F3 or Esc'],
-      ['Focus IO cache', 'F4'],
-      ['Leave IO cache', 'F4 or Esc'],
+      ['Focus IO trace', 'F4'],
+      ['Leave IO trace', 'F4 or Esc'],
       ['Jump to definition', 'F5', 'gd'],
       ['Expand selection to eval expression', 'Ctrl-↓ or Ctrl-j'],
       ['Collapse selection', 'Ctrl-↑ or Ctrl-k'],
@@ -376,7 +376,7 @@ export class UI {
       ['Step out of call', 'Ctrl-o', '\\o'],
       ['When in call tree view, jump to return statement', 'Enter'],
       ['When in call tree view, jump to function arguments', 'a'],
-      ['Clear IO cache', 'F6'],
+      ['Clear IO trace', 'F6'],
       ['(Re)open run window (F7)', 'F7'],
       ['Expand/collapse editor to fullscreen', 'F8'],
     ]
diff --git a/src/effects.js b/src/effects.js
index 466bcc3..64d8e20 100644
--- a/src/effects.js
+++ b/src/effects.js
@@ -225,11 +225,11 @@ export const apply_side_effects = (prev, next, command, ui) => {
         ui.logs.rerender_logs(next.logs)
 
         if(
-          prev.io_cache != next.io_cache 
+          prev.io_trace != next.io_trace 
           || 
-          prev.eval_cxt?.io_cache_index != next.eval_cxt.io_cache_index
+          prev.eval_cxt?.io_trace_index != next.eval_cxt.io_trace_index
         ) {
-          ui.render_io_cache(next)
+          ui.render_io_trace(next)
         }
       }
 
diff --git a/src/eval.js b/src/eval.js
index 28df1b3..4721c4d 100644
--- a/src/eval.js
+++ b/src/eval.js
@@ -294,7 +294,7 @@ export const eval_modules = (
   external_imports, 
   on_deferred_call,
   calltree_changed_token,
-  io_cache,
+  io_trace,
   location
 ) => {
   // TODO gensym __cxt, __trace, __trace_call
@@ -350,7 +350,7 @@ export const eval_modules = (
     window: globalThis.run_window,
   }
 
-  const result = run(module_fns, cxt, io_cache)
+  const result = run(module_fns, cxt, io_trace)
 
   const make_result = result => {
     const calltree = assign_code(parse_result.modules, result.calltree)
@@ -363,7 +363,7 @@ export const eval_modules = (
       eval_cxt: result.eval_cxt,
       calltree,
       call,
-      io_cache: result.eval_cxt.io_cache,
+      io_trace: result.eval_cxt.io_trace,
     }
   }
 
diff --git a/src/record_io.js b/src/record_io.js
index 6ae5700..483a912 100644
--- a/src/record_io.js
+++ b/src/record_io.js
@@ -32,7 +32,7 @@ const io_patch = (path, use_context = false) => {
 
 const make_patched_method = (original, name, use_context) => {
   const method = function(...args) {
-    if(cxt.io_cache_is_replay_aborted) {
+    if(cxt.io_trace_is_replay_aborted) {
       // Try to finish fast
       // TODO invoke callback to notify that code must be restarted?
       throw new Error('io replay aborted')
@@ -41,7 +41,7 @@ const make_patched_method = (original, name, use_context) => {
     const has_new_target = new.target != null
 
     if(cxt.is_recording_deferred_calls) {
-      // TODO record cache on deferred calls?
+      // TODO record trace on deferred calls?
       return has_new_target 
         ? new original(...args)
         : original.apply(this, args)
@@ -49,7 +49,7 @@ const make_patched_method = (original, name, use_context) => {
 
     const cxt_copy = cxt
 
-    if(cxt.io_cache_is_recording) {
+    if(cxt.io_trace_is_recording) {
       let ok, value, error
       try {
         // save call, so on expand_call and find_call IO functions would not be
@@ -58,7 +58,7 @@ const make_patched_method = (original, name, use_context) => {
         // lib and async context is lost
         set_record_call(cxt)
 
-        const index = cxt.io_cache.length
+        const index = cxt.io_trace.length
 
         if(name == 'setTimeout') {
           args = args.slice()
@@ -69,11 +69,11 @@ const make_patched_method = (original, name, use_context) => {
               // If code execution was cancelled, then never call callback
               return
             }
-            if(cxt.io_cache_is_replay_aborted) {
+            if(cxt.io_trace_is_replay_aborted) {
               // Non necessary
               return
             }
-            cxt.io_cache.push({type: 'resolution', index})
+            cxt.io_trace.push({type: 'resolution', index})
             cb()
           }, 'name', {value: cb.name})
         }
@@ -89,11 +89,11 @@ const make_patched_method = (original, name, use_context) => {
             if(cxt_copy != cxt) {
               return
             }
-            if(cxt.io_cache_is_replay_aborted) {
+            if(cxt.io_trace_is_replay_aborted) {
               // Non necessary
               return
             }
-            cxt.io_cache.push({type: 'resolution', index})
+            cxt.io_trace.push({type: 'resolution', index})
           })
         }
 
@@ -104,7 +104,7 @@ const make_patched_method = (original, name, use_context) => {
         ok = false
         throw e
       } finally {
-        cxt.io_cache.push({
+        cxt.io_trace.push({
           type: 'call',
           name,
           ok, 
@@ -119,11 +119,11 @@ const make_patched_method = (original, name, use_context) => {
         })
       }
     } else {
-      const call = cxt.io_cache[cxt.io_cache_index]
+      const call = cxt.io_trace[cxt.io_trace_index]
 
       // TODO if call == null or call.type == 'resolution', then do not discard
-      // cache, instead switch to record mode and append new calls to the
-      // cache?
+      // trace, instead switch to record mode and append new calls to the
+      // trace?
       if(
         call == null
         || call.type != 'call'
@@ -140,53 +140,53 @@ const make_patched_method = (original, name, use_context) => {
             )
            )
       ){
-        cxt.io_cache_is_replay_aborted = true
+        cxt.io_trace_is_replay_aborted = true
         // Try to finish fast
         throw new Error('io replay aborted')
       } else {
 
-        const next_resolution = cxt.io_cache.find((e, i) => 
-          e.type == 'resolution' && i > cxt.io_cache_index
+        const next_resolution = cxt.io_trace.find((e, i) => 
+          e.type == 'resolution' && i > cxt.io_trace_index
         )
 
-        if(next_resolution != null && !cxt.io_cache_resolver_is_set) {
+        if(next_resolution != null && !cxt.io_trace_resolver_is_set) {
           const original_setTimeout = cxt.window.setTimeout.__original
-          cxt.io_cache_resolver_is_set = true
+          cxt.io_trace_resolver_is_set = true
 
           original_setTimeout(() => {
             if(cxt_copy != cxt) {
               return
             }
 
-            if(cxt.io_cache_is_replay_aborted) {
+            if(cxt.io_trace_is_replay_aborted) {
               return
             }
 
-            cxt.io_cache_resolver_is_set = false
+            cxt.io_trace_resolver_is_set = false
 
             // Sanity check
-            if(cxt.io_cache_index >= cxt.io_cache.length) {
+            if(cxt.io_trace_index >= cxt.io_trace.length) {
               throw new Error('illegal state')
             }  
 
-            const next_event = cxt.io_cache[cxt.io_cache_index]
+            const next_event = cxt.io_trace[cxt.io_trace_index]
             if(next_event.type == 'call') {
-              cxt.io_cache_is_replay_aborted = true
+              cxt.io_trace_is_replay_aborted = true
             } else {
               while(
-                cxt.io_cache_index < cxt.io_cache.length 
+                cxt.io_trace_index < cxt.io_trace.length 
                 && 
-                cxt.io_cache[cxt.io_cache_index].type == 'resolution'
+                cxt.io_trace[cxt.io_trace_index].type == 'resolution'
               ) {
-                const resolution = cxt.io_cache[cxt.io_cache_index]
-                const resolver = cxt.io_cache_resolvers.get(resolution.index)
+                const resolution = cxt.io_trace[cxt.io_trace_index]
+                const resolver = cxt.io_trace_resolvers.get(resolution.index)
 
-                cxt.io_cache_index++
+                cxt.io_trace_index++
 
-                if(cxt.io_cache[resolution.index].name == 'setTimeout') {
+                if(cxt.io_trace[resolution.index].name == 'setTimeout') {
                   resolver()
                 } else {
-                  resolver(cxt.io_cache[resolution.index].value)
+                  resolver(cxt.io_trace[resolution.index].value)
                 }
               }
             }
@@ -194,17 +194,17 @@ const make_patched_method = (original, name, use_context) => {
             }, 0)
         }
 
-        cxt.io_cache_index++
+        cxt.io_trace_index++
 
         if(call.ok) {
           if(call.value instanceof cxt.window.Promise) {
             // Always make promise originate from run_window
             return new cxt.window.Promise(resolve => {
-              cxt.io_cache_resolvers.set(cxt.io_cache_index - 1, resolve)
+              cxt.io_trace_resolvers.set(cxt.io_trace_index - 1, resolve)
             })
           } else if(name == 'setTimeout') {
             const timeout_cb = args[0]
-            cxt.io_cache_resolvers.set(cxt.io_cache_index - 1, timeout_cb)
+            cxt.io_trace_resolvers.set(cxt.io_trace_index - 1, timeout_cb)
             return call.value
           } else {
             return call.value
@@ -253,9 +253,9 @@ export const apply_io_patches = () => {
   io_patch(['Math', 'random'])
 
   io_patch(['setTimeout'])
-  // TODO if call setTimeout and then clearTimeout, cache it and remove call of
+  // TODO if call setTimeout and then clearTimeout, trace it and remove call of
   // clearTimeout, and make only setTimeout, then it would never be called when
-  // replaying from cache
+  // replaying from trace
   io_patch(['clearTimeout'])
 
   // TODO patch setInterval to only cleanup all intervals on finish
diff --git a/src/runtime.js b/src/runtime.js
index 752c51e..07072c9 100644
--- a/src/runtime.js
+++ b/src/runtime.js
@@ -29,23 +29,23 @@ const gen_to_promise = gen_fn => {
   }
 }
 
-const do_run = function*(module_fns, cxt, io_cache){
+const do_run = function*(module_fns, cxt, io_trace){
   let calltree
 
-  cxt = (io_cache == null || io_cache.length == 0)
-    // TODO group all io_cache_ properties to single object?
+  cxt = (io_trace == null || io_trace.length == 0)
+    // TODO group all io_trace_ properties to single object?
     ? {...cxt,
-      io_cache_is_recording: true,
-      io_cache: [],
+      io_trace_is_recording: true,
+      io_trace: [],
     }
     : {...cxt,
-      io_cache_is_recording: false,
-      io_cache,
-      io_cache_is_replay_aborted: false,
-      io_cache_resolver_is_set: false,
-      // Map of (index in io_cache) -> resolve
-      io_cache_resolvers: new Map(),
-      io_cache_index: 0,
+      io_trace_is_recording: false,
+      io_trace,
+      io_trace_is_replay_aborted: false,
+      io_trace_resolver_is_set: false,
+      // Map of (index in io_trace) -> resolve
+      io_trace_resolvers: new Map(),
+      io_trace_index: 0,
     }
 
   apply_promise_patch(cxt)
@@ -94,14 +94,14 @@ const do_run = function*(module_fns, cxt, io_cache){
   }
 }
 
-export const run = gen_to_promise(function*(module_fns, cxt, io_cache) {
-  const result = yield* do_run(module_fns, cxt, io_cache)
+export const run = gen_to_promise(function*(module_fns, cxt, io_trace) {
+  const result = yield* do_run(module_fns, cxt, io_trace)
 
-  if(result.eval_cxt.io_cache_is_replay_aborted) {
+  if(result.eval_cxt.io_trace_is_replay_aborted) {
     // TODO test next line
     result.eval_cxt.is_recording_deferred_calls = false
 
-    // run again without io cache
+    // run again without io trace
     return yield* do_run(module_fns, cxt, null)
   } else {
     return result
diff --git a/test/test.js b/test/test.js
index 5dd5ac6..81505d8 100644
--- a/test/test.js
+++ b/test/test.js
@@ -3172,7 +3172,7 @@ const y = x()`
 
     const next = COMMANDS.input(initial, `const x = Math.random()*2`, 0).state
     assert_equal(next.value_explorer.result.value, 2)
-    assert_equal(next.eval_cxt.io_cache_index, 1)
+    assert_equal(next.eval_cxt.io_trace_index, 1)
 
     // Patch Math.random to return 2. 
     // TODO The first call to Math.random() is cached with value 1, and the
@@ -3192,7 +3192,7 @@ const y = x()`
   }),
 
 
-  test('record io cache discarded if args does not match', async () => {
+  test('record io trace discarded if args does not match', async () => {
     // Patch fetch
     patch_builtin('fetch', async () => 'first')
 
@@ -3318,19 +3318,19 @@ const y = x()`
     patch_builtin('fetch', null)
   }),
 
-  test('record io clear io cache', async () => {
+  test('record io clear io trace', async () => {
     const s1 = test_initial_state(`Math.random()`)
     const rnd = s1.value_explorer.result.value
     const s2 = COMMANDS.input(s1, `Math.random() + 1`, 0).state
     assert_equal(s2.value_explorer.result.value, rnd + 1)
-    const cleared = COMMANDS.clear_io_cache(s2)
+    const cleared = COMMANDS.clear_io_trace(s2)
     assert_equal(
       cleared.value_explorer.result.value == rnd + 1,
       false
     )
   }),
 
-  test('record io no io cache on deferred calls', async () => {
+  test('record io no io trace on deferred calls', async () => {
     const code = `
       const x = Math.random
       export const fn = () => x()
@@ -3344,7 +3344,7 @@ const y = x()`
     const state = on_deferred_call(i)
 
     // Deferred calls should not be record in cache
-    assert_equal(state.eval_cxt.io_cache.length, 0)
+    assert_equal(state.eval_cxt.io_trace.length, 0)
   }),
 
   test('record io discard prev execution', () => {
@@ -3361,19 +3361,19 @@ const y = x()`
 
   test('record io Date', () => {
     assert_equal(
-      test_initial_state('new Date()').io_cache.length,
+      test_initial_state('new Date()').io_trace.length,
       1
     )
     assert_equal(
-      test_initial_state('new Date("2020-01-01")').io_cache,
+      test_initial_state('new Date("2020-01-01")').io_trace,
       undefined,
     )
     assert_equal(
-      typeof(test_initial_state('Date()').io_cache[0].value),
+      typeof(test_initial_state('Date()').io_trace[0].value),
       'string',
     )
     assert_equal(
-      typeof(test_initial_state('new Date()').io_cache[0].value),
+      typeof(test_initial_state('new Date()').io_trace[0].value),
       'object',
     )
   }),