// Koru Standard Library: the `runcached` part of interpreter — the cached
// fast path. Joined via `~part runcached` in interpreter.kz; merged into
// the interpreter module at load.
//
// `run-cached` reuses a parsed flow for identical source input — the same
// contract as `run`, minus the parse.
~[retain] pub tor run-cached {
    source: string,
    dispatcher: DispatchFn,
    cost_fn: ?CostFn,
    creates_obligations_fn: ?ObligationsArrayFn,
    discharges_obligations_fn: ?ObligationsArrayFn,
    discharge_event_fn: ?DischargeEventFn,
    creates_spec_fn: ?CreatesSpecFn,
    discharges_spec_fn: ?DischargesSpecFn,
    budget: ?u64,
    handle_pool: ?*HandlePool,
    fail_fast: bool,
    scope_name: string,
    auto_discharge: bool,
    defined: ?*DefinedFlows,
    input_fn: ?InputLookupFn,
    lenient: bool,
    host_dispatch: ?HostDispatchFn,
    session_env: ?*Environment,
    session_bind_fn: ?SessionBindFn,
    session_bind_env: ?*Environment,
    session_bind_counter: ?*u64
}
| result { value: Value, used: u64, handles: u32, bound: string, trace: string }
| unhandled-branch { branch: string, payload: string, handles: string }
| exhausted { used: u64, last_event: string, handles: u32 }
| parse-error { message: string, line: u32, column: u32 }
| validation-error string
| dispatch-error { event_name: string, message: string, trace: string }