Show a bool as true or false, and make the examples' flags bools

aup and Pure now have a bool (Pure 016): a view or column may be one.
vega_text writes it as true or false, as a string's interpolation does, so
every surface shows the same words: the CLI, the TUI's cells, speech and
the web surface's JSON (a value's text) and page. An app that wants other
words picks them with a conditional (if t.done { "done" } else { "" }).

The flags of the examples are bools: todo's done and urgent, today's done,
the stopwatch's running. vega.when takes the bool as it took the number.

bools checks a bool field and a bool column on the CLI, the TUI, speech
and the web surface: true and false, never 1 and 0.

6 files changed, 65 insertions, 11 deletions

diff --git a/docs/design/001-first-component.md b/docs/design/001-first-component.md
index d3ba7e6..9e1ef80 100644
--- a/docs/design/001-first-component.md
+++ b/docs/design/001-first-component.md
@@ -62,6 +62,9 @@ Tab이 키 모드로 바꾸면 글자·숫자·Space가 `KeyA`·`Digit0`·`Space
 **값이 보이는 방식.** 값은 제 자리 안에서 제 글자로 보인다. 화면에 작용할 글자만 예외다(Pure
 `docs/design/015-boundary-meaning.md`가 정한 값의 뜻의 화면 쪽이다).
 
+- 수는 Pure의 가장 짧은 글자로, bool은 `true`나 `false`로 보인다. 보간(`"{done}"`)과 같은 글자다. 다르게 보이고
+  싶은 앱은 조건식으로 글을 고른다(`if t.done { "완료" } else { "" }`).
+
 - 제어 문자(C0)와 DEL은 제어 그림(␀…␟, ␡)으로, C1 제어는 �로, 줄과 문단의 구분자(U+2028, U+2029)는 ␤로 보인다
   (`vega_visible`). CLI, TUI, 픽셀, 웹 페이지가 모두 같다. 값은 제 줄을 끊지 못한다.
 - 터미널의 칸(TUI, CLI)에서는 뒤따르는 글줄을 뒤집을 제어(방향 임베딩·오버라이드·격리, U+202A–202E, U+2066–2069)도
diff --git a/examples/stopwatch.aup b/examples/stopwatch.aup
index cd075b0..d5408a0 100644
--- a/examples/stopwatch.aup
+++ b/examples/stopwatch.aup
@@ -6,7 +6,7 @@ record Lap {
   at = 0
 }
 
-state running = 0
+state running = false
 state started = 0
 state elapsed = 0
 state laps: list of Lap
diff --git a/examples/today.aup b/examples/today.aup
index e5db53b..65e533f 100644
--- a/examples/today.aup
+++ b/examples/today.aup
@@ -5,7 +5,7 @@ use vega
 
 record Task {
   title: text
-  done = 0
+  done = false
 }
 
 state tasks: list of Task
diff --git a/examples/todo.aup b/examples/todo.aup
index f1e3825..57c6954 100644
--- a/examples/todo.aup
+++ b/examples/todo.aup
@@ -4,8 +4,8 @@ use vega
 
 record Task {
   title: text
-  done = 0
-  urgent = 0
+  done = false
+  urgent = false
 }
 
 state tasks: list of Task
diff --git a/surfaces/screen.c b/surfaces/screen.c
index f079bd5..51181a5 100644
--- a/surfaces/screen.c
+++ b/surfaces/screen.c
@@ -163,10 +163,13 @@ bool vega_text(PureApp *app, uint32_t view, size_t row, char out[VEGA_TEXT], siz
     ++evaluations;
     *length = 0;
     out[0] = 0;
-    if (m->view_type[view] == PURE_VIEW_NUM) {
+    if (m->view_type[view] == PURE_VIEW_NUM || m->view_type[view] == PURE_VIEW_BOOL) {
         double value;
         if (!(column ? pure_app_cell(app, view, row, &value) : pure_app_view(app, view, &value))) return false;
-        *length = pure_format_number(value, out);
+        if (m->view_type[view] == PURE_VIEW_BOOL) { /* a bool is written true or false, as a string shows it */
+            *length = value ? 4 : 5;
+            memcpy(out, value ? "true" : "false", *length);
+        } else *length = pure_format_number(value, out);
         out[*length] = 0;
         return true;
     }
diff --git a/tests/check.py b/tests/check.py
index 4f87d20..5b37646 100644
--- a/tests/check.py
+++ b/tests/check.py
@@ -95,7 +95,7 @@ class Todo:
             self.at = text
             return True
         if name == 'add':
-            self.tasks.append({'title': text, 'done': 0, 'urgent': 0})
+            self.tasks.append({'title': text, 'done': False, 'urgent': False})
             self.at = len(self.tasks) - 1
             return True
         last = max(len(self.tasks) - 1, 0)
@@ -103,8 +103,8 @@ class Todo:
             return False
         if name == 'up': self.at = max(self.at - 1, 0)
         elif name == 'down': self.at = min(self.at + 1, last)
-        elif name == 'toggle': self.tasks[self.at]['done'] = int(not self.tasks[self.at]['done'])
-        elif name == 'urgent': self.tasks[self.at]['urgent'] = int(not self.tasks[self.at]['urgent'])
+        elif name == 'toggle': self.tasks[self.at]['done'] = not self.tasks[self.at]['done']
+        elif name == 'urgent': self.tasks[self.at]['urgent'] = not self.tasks[self.at]['urgent']
         elif name == 'drop':
             del self.tasks[self.at]
             self.at = min(self.at, max(len(self.tasks) - 1, 0))
@@ -527,7 +527,7 @@ def split(vega, module, work, seeds, steps=200):
             if roll < 0.3:
                 word = rng.choice(WORDS)
                 script.append('text ' + (word.encode().hex() or '-'))
-                tasks.append({'title': word, 'done': 0})
+                tasks.append({'title': word, 'done': False})
                 at = len(tasks) - 1
             elif roll < 0.5:
                 name, rows = rng.choice([('open', opened), ('done', closed)])
@@ -539,7 +539,7 @@ def split(vega, module, work, seeds, steps=200):
                 script.append(f'key {key}')
                 if key == 'ArrowUp': at = max(at - 1, 0)
                 elif key == 'ArrowDown': at = min(at + 1, max(len(tasks) - 1, 0))
-                elif tasks: tasks[at]['done'] = int(not tasks[at]['done'])
+                elif tasks: tasks[at]['done'] = not tasks[at]['done']
             if rng.random() < 0.3:
                 script.append('show')
                 opened = [i for i, t in enumerate(tasks) if not t['done']]
@@ -1898,6 +1898,53 @@ def screen_meaning(vega, aup, work):
     return {'values': len(SCREEN_TEXTS), 'surfaces': 4}
 
 
+BOOL_APP = """use vega
+record Row {
+  n = 0
+}
+state lit = false
+state rows: list of Row
+input flip = key Space
+input add = text
+on flip.down { lit = !lit }
+on add { rows.append(Row { n: add.chars }) }
+view shown = lit
+view sizes = each r in rows {
+  n = r.n
+  over = r.n > 2
+}
+"""
+
+
+def bools(vega, aup, work):
+    """A bool shows as true or false on every surface (the CLI, the TUI's
+    cells, speech and the web surface's JSON), as a string shows it: never
+    as 1 or 0."""
+    source, module = work / 'bools.aup', work / 'bools.pmod'
+    source.write_text(BOOL_APP)
+    built = run(aup, 'build', source, '-o', module, env=dict(os.environ, AUP_PATH=str(ROOT / 'lib')))
+    assert built.returncode == 0, built.stderr
+    script = 'show\nkey Space\ntext 61\ntext 61626364\nshow\n'  # a has one character, abcd four
+    out = run(vega, 'cli', module, stdin=script).stdout.splitlines()
+    assert out == ['shown: false', 'sizes (0)', '  n  over', 'shown: true', 'sizes (2)', '  n  over', '> 1  false',
+                   '  4  true'], out
+    dump = run(vega, 'tui', module, '--dump', '30x8', stdin=script).stdout.splitlines()
+    assert all(line in dump for line in ['|shown  false\tmuted', '|shown  true\tmuted', '>> 1  false', '|  4  true']), dump
+    said = run(vega, 'say', module, stdin=script).stdout.splitlines()
+    assert all(line in said for line in ['shown: false.', 'shown: true.', 'Item 1 of 2: n 1, over false.']), said
+    surface = WebSurface(vega, module)
+    try:
+        surface.call('POST', '/key', 'Space')
+        for text in ('a', 'abcd'): surface.call('POST', '/text', text)
+        screen = json.loads(surface.call('GET', '/screen?rows=5')[1])
+    finally:
+        surface.stop()
+    assert screen['fields'] == [{'name': 'shown', 'text': 'true'}], screen['fields']
+    table = screen['parts'][0]
+    assert table['columns'] == ['n', 'over'] and [item['cells'] for item in table['items']] == [['1', 'false'], ['4', 'true']], table
+    return len(out) + len(dump) + len(said)
+
+
 def main():
     parser = argparse.ArgumentParser()
     parser.add_argument('--vega', type=Path, required=True)
@@ -1928,6 +1975,7 @@ def main():
         report['board_rows_across_hosts'] = hosts(vega, args.serve.resolve(), modules['board'], work)
         report['hot_swap_lines'] = hot_swap(vega, aup, work)
         report['split_list_lines'] = split(vega, modules['today'], work, range(args.seeds))
+        report['bool_lines'] = bools(vega, aup, work)
         report['painted_frames'], report['first_paint_bytes'], report['later_paint_bytes'] = \
             painting(vega, modules['todo'], range(args.seeds), [(40, 12), (24, 9), (80, 30)])
         report['web_screens'] = web(vega, modules['todo'], work, range(args.seeds))