I read the STM slides you linked and I have a follow up question:

Slide 26 says "STM is aimed at shared memory [applications]..." and slide 31 says "You can't do IO in a memory transaction...", which leads me to ask, what is the point of concurrency that cannot do IO?

The basic premise of concurrency is to overlap communications with computations. You utilise the time spent communicating to do something else useful.

In the case of the example used in the slides, that of a banking system, the instructions for increasing and decreasing an account's total would, in the real world, be coming from external systems--clearing houses, ATM's, check processing in branch work rooms etc.--and any but the smallest bank would have to be using multiple (many) systems to process the volumes of transactions and accounts in real time.

If STM is restricted to dealing only with in-memory concurrency, it seems to be of little real-world application beyond simulations?

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
Lingua non convalesco, consenesco et abolesco.
Rule 1 has a caveat! -- Who broke the cabal?

In reply to Re^7: GHC shuffle more efficient than Perl5. by BrowserUk
in thread Why is the execution order of subexpressions undefined? by BrowserUk

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