Memo

A memo is a derived value — it computes a result from other signals and caches it. Memos are lazy: they only recompute when their dependencies change and their value is actually requested. This makes them efficient for expensive computations.

Creating a Memo

let (a, set_a) = @reactive.create_signal(1)
let (b, set_b) = @reactive.create_signal(2)

let sum = @reactive.Memo::new(fn(_prev) {
  a.get() + b.get()
})

sum now tracks a and b as dependencies. Reading sum.get() returns the cached value or triggers recomputation if a or b changed.

When to Use Memos

Use memos when:

• A value is derived from multiple signals and used in several places
• The computation is expensive (filtering, formatting, transforming data)
• You want to avoid redundant work

Without a memo, the computation runs every time a component re-renders. With a memo, it runs once and caches.

Glitch-Free Propagation

Aitne’s reactive system handles diamond dependencies correctly. If A and B depend on Source, and C depends on both A and B, then C only recomputes once when Source changes, always seeing consistent values for A and B.