Section 16: Async Support

Goal: Async/await semantics via capabilities

SPEC: spec/20-capabilities.md § Async Capability DESIGN: design/10-async/index.md

Dependencies: Section 6 (Capabilities — uses Async/uses Suspend capability declarations and propagation)

PREREQUISITE FOR: Section 17 (Concurrency Extended) — select, cancellation, enhanced channels.

NOTE: This section is thin (153 lines) for an entire async support system. Before implementation, expand with: async runtime architecture, task scheduling model, stack/stackless coroutine decision, interaction with ARC memory management, and async-specific error handling details.

Future Enhancements: Approved proposal parallel-concurrency-proposal.md adds:

• Sendable trait for safe cross-task transfer
• Role-based channels (Producer<T>, Consumer<T>)
• Ownership transfer semantics for channel send
• Process isolation primitives See Section 17 for implementation details.

16.1 Async via Capability

• Implement: uses Async declaration — spec/20-capabilities.md § Async Capability, design/10-async/index.md § Async via Capability

  • Rust Tests: ori_types/src/check/capabilities.rs — async capability
  • Ori Tests: tests/spec/async/declaration.ori
  • LLVM Support: LLVM codegen for async capability declaration
  • LLVM Rust Tests: ori_llvm/tests/async_tests.rs — async capability declaration codegen
  • AOT Tests: No AOT coverage yet

• Implement: Sync vs async distinction — spec/20-capabilities.md § Async Capability, design/10-async/index.md § Sync vs Async

  • Rust Tests: ori_types/src/check/capabilities.rs — sync/async distinction
  • Ori Tests: tests/spec/async/sync_async.ori
  • LLVM Support: LLVM codegen for sync/async distinction
  • LLVM Rust Tests: ori_llvm/tests/async_tests.rs — sync/async distinction codegen
  • AOT Tests: No AOT coverage yet

16.2 Structured Concurrency

• Implement: Structured concurrency — design/10-async/index.md § Structured Concurrency

  • Rust Tests: ori_eval/src/interpreter/async.rs — structured concurrency
  • Ori Tests: tests/spec/async/structured.ori
  • LLVM Support: LLVM codegen for structured concurrency
  • LLVM Rust Tests: ori_llvm/tests/async_tests.rs — structured concurrency codegen
  • AOT Tests: No AOT coverage yet

• Implement: No shared mutable state — design/10-async/index.md § No Shared Mutable State

  • Rust Tests: ori_types/src/check/mutability.rs — shared state detection
  • Ori Tests: tests/spec/async/no_shared_state.ori
  • LLVM Support: LLVM codegen for no shared mutable state enforcement
  • LLVM Rust Tests: ori_llvm/tests/async_tests.rs — no shared mutable state codegen
  • AOT Tests: No AOT coverage yet

16.3 Concurrency Patterns

• Implement: parallel pattern — spec/15-patterns.md § parallel, design/02-syntax/04-patterns-reference.md § parallel

  • Rust Tests: ori_patterns/src/parallel.rs — parallel pattern async
  • Ori Tests: tests/spec/async/parallel.ori
  • LLVM Support: LLVM codegen for parallel pattern
  • LLVM Rust Tests: ori_llvm/tests/async_tests.rs — parallel pattern codegen
  • AOT Tests: No AOT coverage yet

• Implement: timeout pattern — spec/15-patterns.md § timeout, design/02-syntax/04-patterns-reference.md § timeout

  • Rust Tests: ori_patterns/src/timeout.rs — timeout pattern async
  • Ori Tests: tests/spec/async/timeout.ori
  • LLVM Support: LLVM codegen for timeout pattern
  • LLVM Rust Tests: ori_llvm/tests/async_tests.rs — timeout pattern codegen
  • AOT Tests: No AOT coverage yet

• Implement: Channels — spec/08-types.md § Channel

  • Rust Tests: ori_eval/src/interpreter/channel.rs — channel implementation
  • Ori Tests: tests/spec/async/channels.ori
  • LLVM Support: LLVM codegen for channels
  • LLVM Rust Tests: ori_llvm/tests/concurrency_tests.rs — channels codegen
  • AOT Tests: No AOT coverage yet

16.4 Async Error Traces

Proposal: proposals/approved/error-trace-async-semantics-proposal.md

Implements error trace preservation across task boundaries in async code.

• Implement: Task boundary marker in traces — spec/17-errors-and-panics.md § Task Boundary Marker

  • Rust Tests: ori_eval/src/interpreter/async.rs — task boundary marker tests
  • Ori Tests: tests/spec/async/trace_boundary.ori
  • LLVM Support: LLVM codegen for task boundary marker
  • LLVM Rust Tests: ori_llvm/tests/async_tests.rs — task boundary marker codegen
  • AOT Tests: No AOT coverage yet

• Implement: Trace preservation across parallel tasks — spec/17-errors-and-panics.md § Trace from Parallel Tasks

  • Rust Tests: ori_eval/src/interpreter/async.rs — parallel trace tests
  • Ori Tests: tests/spec/async/parallel_traces.ori
  • LLVM Support: LLVM codegen for parallel trace preservation
  • LLVM Rust Tests: ori_llvm/tests/async_tests.rs — parallel trace codegen
  • AOT Tests: No AOT coverage yet

• Implement: Trace preservation across nursery tasks — spec/17-errors-and-panics.md § Async Error Traces

  • Rust Tests: ori_eval/src/interpreter/nursery.rs — nursery trace tests
  • Ori Tests: tests/spec/async/nursery_traces.ori
  • LLVM Support: LLVM codegen for nursery trace preservation
  • LLVM Rust Tests: ori_llvm/tests/async_tests.rs — nursery trace codegen
  • AOT Tests: No AOT coverage yet

• Implement: Catch and panic trace interaction — spec/17-errors-and-panics.md § Catch and Panic Traces

  • Rust Tests: ori_eval/src/interpreter/catch.rs — catch trace tests
  • Ori Tests: tests/spec/errors/catch_traces.ori
  • LLVM Support: LLVM codegen for catch trace interaction
  • LLVM Rust Tests: ori_llvm/tests/error_tests.rs — catch trace codegen
  • AOT Tests: No AOT coverage yet

16.5 Section Completion Checklist

• All items above have all checkboxes marked [ ]
• Spec updated: spec/20-capabilities.md async section, spec/15-patterns.md concurrency patterns
• CLAUDE.md updated with async/concurrency syntax
• Re-evaluate against docs/compiler-design/v2/02-design-principles.md
• 80+% test coverage, tests against spec/design
• Run full test suite: ./test-all.sh

Exit Criteria: Async code compiles and runs