# 053: Computed Values
# Derived state that updates automatically

state firstname = "Alex"
state lastname = "Chen"

# Computed value - automatically recalculates when dependencies change
computed fullname = "{firstname} {lastname}"

show fullname  # "Alex Chen"

# Update state
button "Change Name" -> change_name()

change_name():
  firstname = "Jordan"
  lastname = "Lee"
  # fullname automatically becomes "Jordan Lee"

# Shopping cart example
state items = [
  { name: "Apple", price: 1.50, quantity: 3 },
  { name: "Banana", price: 0.75, quantity: 5 }
]

computed total = items.reduce((sum, item) => {
  sum + (item.price * item.quantity)
}, 0)

show "Total: ${total}"  # Automatically updates when items change

button "Add Orange" -> add_item()

add_item():
  items.append({ name: "Orange", price: 2.00, quantity: 2 })
  # total automatically recalculates