Re: [Caml-list] STM support in OCaml

[Michael Hicks <mwh@cs.umd.edu>]

There's a longer answer, but one short answer is: check out AtomCaml  
at http://www.cs.washington.edu/homes/miker/atomcaml/

-Mike

On Mar 7, 2006, at 11:50 AM, Sebastian Egner wrote:

>
> > Are there any plans to add STM to OCaml?  And I'm talking highly  
> integrated
> > into the language, not just some bolt-on library.
>
> I implemented 'some bolt-on library' as you call it for
> myself (for understanding the details of STM) but did
> not release it. The main lesseons I learned, however, are
>
> a) A library will be nearly as good as something 'highly
> integrated into the language'. The main difference is
> that you cannot annotate fields to be transactional,
> and define transactional record types; you need to
> work with explicit transactional reference boxes and arrays.
> This appears tolerable, and it is a lot simpler, both in
> terms of implementation and in terms of using it.
>
> b) The version of STM as designed for Haskell makes essential
> use of laziness for composing transactions in a very clean
> way. You can construct more and more complex transactions
> by not yet enclosing them into 'atomic'. This is probably
> the most important benefit of STMs at all. Unfortunately,
> this property is essentially impossible in OCaml: No matter
> how highly integrated STMs are in the language, it will
> always be easy to write a program that uses ordinary (non-STM)
> state to keep a record of something it shouldn't---messing
> up semantics of course.
>
> Sorry, I know this is bad news, but that is what I found.
> I invite everybody to verify this for him- or herself,
> or prove me wrong.
>
> Sebastian.
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