✏️ Mutable
🔒 Immutable
▶ Update (x, y)
👓 Read now
↺ Reset
locks needed:
1
· torn reads:
0
🔒 Add a lock
🕳 shallow trap
one shared object · edited in place
versions:
1
· readers blocked:
0
✍️ Writer
idle
press ▶ Update
📦 Shared state
current ▼
Point
v1
x: 1
y: 2
tags [ ]
Point
v2
x: 9
y: 9
tags [ ]
👓 Readers
👓 Reader A
v1
x: 1 · y: 2
reads mid-write
👓 Reader B
v1
x: 1 · y: 2
reads after write
One object, two readers
Press
▶ Update (x, y)
and watch
Reader A
mid-write.
▸
Every bug here needs
shared + mutable
. Remove
mutable
and there is nothing left to lock.