Macro session_protocol 

session_protocol!() { /* proc-macro */ }

Generates typestate-encoded session types from a protocol DSL.

The macro takes a protocol specification and generates a module containing message structs, paired session type aliases (initiator + responder), and constructor functions. The responder type is the dual of the initiator: Send↔Recv, Select↔Offer.

Syntax

session_protocol! {
    module_name<T> for ObligationVariant {
        msg MessageName;
        msg MessageWithFields { field: Type };

        send MessageName => select {
            send T => end,
            send OtherMsg => end,
        }
    }
}

Body Actions

• send Type => body — send a value, then continue
• recv Type => body — receive a value, then continue
• select { a, b } — local choice (becomes Offer for responder)
• offer { a, b } — remote choice (becomes Select for responder)
• loop { body } — recursion point (generates renew_loop constructor)
• continue — jump back to enclosing loop
• end — protocol termination

Generated Items

• pub mod <name> containing:
  • Message structs with Debug, Clone (+ Copy for unit structs)
  • InitiatorSession type alias
  • ResponderSession type alias
  • new_session(channel_id) -> (Chan<Initiator, ...>, Chan<Responder, ...>)
  • (if loop used) InitiatorLoop, ResponderLoop type aliases
  • (if loop used) renew_loop(channel_id) constructor

Example

session_protocol! {
    lease for Lease {
        msg AcquireMsg;
        msg RenewMsg;
        msg ReleaseMsg;

        send AcquireMsg => loop {
            select {
                send RenewMsg => continue,
                send ReleaseMsg => end,
            }
        }
    }
}