Example	Level	Demonstrates
`counter_simple`	Introductory	Basic host-driven polling via `HostHandle` + `PollOnce`
`counter_effects`	Introductory	Sans-IO effect protocol with `EffectSlot` + `EffectHandle`
`key_value_store`	Intermediate	Per-future `Arc<EffectSlot>`, concurrent operations, multi-step futures

Progression #

Start with counter_simple to understand the basic polling loop, then counter_effects to see how futures request capabilities from the host, then key_value_store for concurrent operations with independent effect channels.

counter_simple       counter_effects       key_value_store
──────────────>  ───────────────────>  ─────────────────────>
  poll_once()      EffectSlot             Arc<EffectSlot>
  HostHandle       EffectHandle           per-future slots
  blind poll       effect dispatch        concurrent futures

Running #

Each example has a run_test.sh that builds the Rust cdylib and runs all host implementations. Foreign toolchains (Go, Java, Python) are available via nix develop .#ffi:

nix develop .#ffi

./future_form_ffi/examples/counter_simple/run_test.sh
./future_form_ffi/examples/counter_effects/run_test.sh
./future_form_ffi/examples/key_value_store/run_test.sh

The counter_simple tokio host needs only Rust:

cargo run --manifest-path future_form_ffi/examples/counter_simple/tokio_host/Cargo.toml