Concurrency

Under construction

The concurrency chapter is being rewritten alongside the reactor and effects work. The shape that exists today (tasks: scopes, spawn / spawn_blocking / join, parallel_for_chunks) is stable, but the direct-style async I/O extension (effects in signatures, no async / await) is in progress.

This page will land in detail once that work is merged.

For now, the canonical references are:

• docs/concurrency_engine.md in the repository: current structured concurrency design (tasks, work-stealing scheduler, blocking pool).
• docs/direct_style_concurrency.md: design notes for the in-progress effects + reactor extension.

Once the implementation lands, this page will cover:

• tasks: scopes: opening a structured scope where children can’t outlive the parent.
• spawn, spawn_blocking, join: starting CPU and blocking work; consuming task handles.
• parallel_for_chunks: statement-only data-parallel helper for slice workloads.
• Effects in signatures: how suspends, blocking, and offloads_blocking are declared and checked.
• Reactor model: how I/O readiness wakes tasks without splitting the language into async and sync variants.