Erlang Meets Dependent Types

Talk given at EdLambda, in July 2015.

Dissertation Link: http://lenary.co.uk/publications/dissertation/

Transcript

1. Erlang Meets Dependent Types Sam Elliott edλ, 14 July 2015
2. Erlang Dependent Types Compiler Concurrency OTP Conclusion Erlang • Actor-based Concurrent Programming Language • !, receive, and spawn • Mailbox per Isolated Process Sam Elliott Erlang Meets Dependent Types
3. Erlang Dependent Types Compiler Concurrency OTP Conclusion Erlang Advanced Features • Dynamically Typed • dialyzer • OTP: Behaviours Sam Elliott Erlang Meets Dependent Types
4. Erlang Dependent Types Compiler Concurrency OTP Conclusion Dependently-Typed Languages • Idris • Agda • Coq Sam Elliott Erlang Meets Dependent Types
5. Erlang Dependent Types Compiler Concurrency OTP Conclusion Idris • Dependently-typed Pure Programming Language • Types are Values • Values are Types • Programs and Proofs Sam Elliott Erlang Meets Dependent Types
6. Erlang Dependent Types Compiler Concurrency OTP Conclusion Idris IRs “Cross-platform Compilers for Functional Languages” • Idris • TT • TTcase • IRcase • IRlift • IRdefunc • IRANF • Idris Bytecode Sam Elliott Erlang Meets Dependent Types
7. Erlang Dependent Types Compiler Concurrency OTP Conclusion IRdefunc Sam Elliott Erlang Meets Dependent Types
8. Erlang Dependent Types Compiler Concurrency OTP Conclusion Actors data Actor : Type → Type → Type proc : Actor l () Sam Elliott Erlang Meets Dependent Types
9. Erlang Dependent Types Compiler Concurrency OTP Conclusion Actors data Actor : Type → Type → Type proc : Actor l () recieve : Actor l l Sam Elliott Erlang Meets Dependent Types
10. Erlang Dependent Types Compiler Concurrency OTP Conclusion Actors data Actor : Type → Type → Type proc : Actor l () recieve : Actor l l spawn : (Actor l’ a) → Actor l (ActorID l’) data ActorID : Type → Type pid : ActorID l Sam Elliott Erlang Meets Dependent Types
11. Erlang Dependent Types Compiler Concurrency OTP Conclusion Actors data Actor : Type → Type → Type proc : Actor l () recieve : Actor l l spawn : (Actor l’ a) → Actor l (ActorID l’) data ActorID : Type → Type pid : ActorID l send : ActorID l’ → l’ → Actor l () Sam Elliott Erlang Meets Dependent Types
12. Erlang Dependent Types Compiler Concurrency OTP Conclusion RPC data RPCLang : (r : Type) → (r → Type) → Type Sam Elliott Erlang Meets Dependent Types
13. Erlang Dependent Types Compiler Concurrency OTP Conclusion RPC data RPCLang : (r : Type) → (r → Type) → Type data LockReq = Lock | Unlock data LockLockResp = Grant | Wait total LockResp : LockReq → Type LockResp Lock = LockLockResp LockResp Unlock = Unit LockLang : RPCLang LockReq LockResp Sam Elliott Erlang Meets Dependent Types
14. Erlang Dependent Types Compiler Concurrency OTP Conclusion RPC II data RPCRef : RPCLang rq rs → Type rpc : {l : RPCLang rq rs} → RPCRef l → (m : rq) → EIO (rs m) Sam Elliott Erlang Meets Dependent Types
15. Erlang Dependent Types Compiler Concurrency OTP Conclusion RPC II data RPCRef : RPCLang rq rs → Type rpc : {l : RPCLang rq rs} → RPCRef l → (m : rq) → EIO (rs m) pid : RPCRef LockLang rpc pid Lock : LockLockResp rpc pid Unlock : Unit Sam Elliott Erlang Meets Dependent Types
16. Erlang Dependent Types Compiler Concurrency OTP Conclusion RPC III spawn : {l : RPCLang rq rs} → (r : rq → rs r) → EIO (RPCRef l) Sam Elliott Erlang Meets Dependent Types
17. Erlang Dependent Types Compiler Concurrency OTP Conclusion RPC III spawn : {l : RPCLang rq rs} → (r : rq → rs r) → EIO (RPCRef l) total lock : (m : LockReq) → LockResp m lock Lock = Grant -- Oh Crap! lock Unlock = () Sam Elliott Erlang Meets Dependent Types
18. Erlang Dependent Types Compiler Concurrency OTP Conclusion RPC III spawn : {l : RPCLang rq rs} → (r : rq → rs r) → EIO (RPCRef l) total lock : (m : LockReq) → LockResp m lock Lock = Grant -- Oh Crap! lock Unlock = () State? Side Effects? Sam Elliott Erlang Meets Dependent Types
19. Erlang Dependent Types Compiler Concurrency OTP Conclusion OTP • “Open Telecoms Platform” • Lots of great defaults • Generic Behaviours! • Supervisors! Sam Elliott Erlang Meets Dependent Types
20. Erlang Dependent Types Compiler Concurrency OTP Conclusion Generic Behaviours • gen server • gen fsm • gen event Sam Elliott Erlang Meets Dependent Types
21. Erlang Dependent Types Compiler Concurrency OTP Conclusion gen server data GSL : (cl : Type) → (cl → Type) → Type → Type data GSRef : GSL cl cr ct → Type Sam Elliott Erlang Meets Dependent Types
22. Erlang Dependent Types Compiler Concurrency OTP Conclusion gen server data GSL : (cl : Type) → (cl → Type) → Type → Type data GSRef : GSL cl cr ct → Type call : {l : GSL cl cr ct} → GSRef l → (m : cl) → EIO (cr m) cast : {l : GSL cl cr ct} → GSRef l → ct → EIO Unit Sam Elliott Erlang Meets Dependent Types
23. Erlang Dependent Types Compiler Concurrency OTP Conclusion gen server data GS : (GSL cl cr ct) → Type → Type → Type spawn : (GS l st i) → i → EIO (GSRef i) Sam Elliott Erlang Meets Dependent Types
24. Erlang Dependent Types Compiler Concurrency OTP Conclusion Conclusion • We can produce verified concurrent programs in Idris • We can compile these programs to work with Erlang • We can run verified programs in Erlang Sam Elliott Erlang Meets Dependent Types
25. Erlang Dependent Types Compiler Concurrency OTP Conclusion Read More Sam Elliott Erlang Meets Dependent Types
26. Erlang Dependent Types Compiler Concurrency OTP Conclusion Thanks To Edwin Brady Rob Stewart Skyscanner & Mike Moran Sam Elliott Erlang Meets Dependent Types
27. Erlang Dependent Types Compiler Concurrency OTP Conclusion Any Questions? Sam Elliott Erlang Meets Dependent Types