More Codex feedback

[cknitt]

Hi @brnrdog, here is some output from another Codex review run:

Findings

• High: Observers leak on initial compute/effect errors. If compute() or the initial effect run throws, the observer stays in Scheduler.observers and keeps any deps it already captured; there is no cleanup or rollback. This can leave stale deps and memory leaks. src/signals/Signals__Computed.res:23, src/signals/Signals__Computed.res:32, src/signals/Signals__Effects.res:23, src/signals/Signals__Effects.res:35.
• Medium: Computeds propagate invalidations even when their derived value doesn’t change. The dirty flag triggers notify(backingSignalId) before recompute, and recompute doesn’t check equality. This causes downstream effects to re-run even if the computed value is effectively unchanged, unlike many signal libs that short-circuit. src/signals/Signals__Scheduler.res:266, src/signals/Signals__Computed.res:14, src/signals/Signals__Signal.res:43.
• Low: No ownership/auto‑disposal model; computed and effect observers persist until manually disposed. This is a common trade‑off but deviates from Solid/Vue patterns where effects are tied to scopes and auto‑cleaned on teardown. src/signals/Signals__Computed.res:55, src/signals/Signals__Effects.res:52.

Comparison to common signal implementations

• Similarities: Uses a global “current observer” for dependency tracking and a dependency graph keyed by signal IDs, like SolidJS and Vue’s effect system. Supports batch and untrack, which mirror typical APIs.
• Differences: Computeds are lazy (only recomputed on read via ensureComputedFresh) and invalidations propagate immediately to dependents; Preact Signals and Solid memos typically use versioning/equality to avoid downstream work when values are unchanged.
• Scheduling: Updates flush synchronously in the same call stack unless batch is used. Many libraries (Preact Signals, Vue) queue microtasks to avoid deep synchronous cascades and improve interleaving.
• Lifecycle: Manual disposal is required for both computeds and effects, while Solid/Vue usually provide ownership scopes and automatic teardown.

[brnrdog]

Hi @cknitt. I’ve recently released several performance-focused updates that involved significant changes to internal structures. Please feel free to run another Codex review against the latest version.

I also benchmarked rescript-signals using the js-reactivity-benchmark, and it is now performing close to the top-performing libraries. I'll attach the results when I get some time.