3 ms·

Thank you, I was wrong. What I initially wanted to say (now that I understand that STM is "CPU concurrency") is that STM is about pure computations. Haskell's S

by k_bx 13y ago

Thank you, I was wrong. What I initially wanted to say (now that I understand that STM is "CPU concurrency") is that STM is about pure computations. Haskell's STM doesn't let you do any kind of IO inside of it. I think PyPy guys had some crazy ideas of connecting STM transactions to SQL transactions, but I have no idea how that will work with network connectivity issues etc.

masklinn 13y ago
> STM is about pure computations. Yes, side-effects (not just I/O, altering non-transactional mutable bindings or objects is also broken) within transactions is fraught with peril as they may be retried time and time again until they succeed. You can still do transactions in languages unable to segregate side-effects, it's just (much) riskier (Clojure/Clojurescript has CAS-based semantics on atoms — usually performed through the higher-level `swap!` operation. It works quite well, but the language will not save you from the footgun of side-effects within a transaction and it will potentially retry hundreds of times if there's a lot of contention on the atom)