Clojure has a commute operator whose semantics seem appropriate to your
concerns:
http://clojure.org/refs
http://richhickey.github.com/clojure/clojure.core-api.html#clojure.core/commute
Commute in haskell would be roughly :: TVar a - (a - a) - STM a.
The TVar touched by commute does not get
Hi Tom,
You wrote that you are interested in the programming experience with relaxed
atomicity. What you are asking for are the ideas behind Twilight STM, written
in these papers:
http://proglang.informatik.uni-freiburg.de/projects/syncstm/techreport2010twilight.pdf
(brief summary of the
Has anyone in the STM community considered the ability to read a TVar,
such that it would allow the transaction to complete even if the TVar
was modified by another transaction? (I am assuming this is not how
STM works by default.) For example:
looselyReadTVar :: TVar a - STM a
Atom [1] has
On 28 September 2010 15:35, Tom Hawkins tomahawk...@gmail.com wrote:
Has anyone in the STM community considered the ability to read a TVar,
such that it would allow the transaction to complete even if the TVar
was modified by another transaction?
Maybe something like this:
(Pasted from
Hi Tom,
you can do this with Twilight STM. I recently uploaded the first version
on hackage[1].
The next version including a better algorithm and examples is about to
be released in a few days.
Twilight STM features include tagging of variables and fine-grained
conflict detection, flexible
On Tue, Sep 28, 2010 at 10:41 AM, Peter Robinson thaldy...@gmail.com wrote:
readTVarIO :: TVar a - IO a
One needs to know if it is ok to wrap this IO action into an STM
action. For example,
data I a = I a
looselyReadTVar :: TVar a - STM a
looselyReadTVar tvar =
let v = unsafePerformIO
On Tue, Sep 28, 2010 at 8:54 AM, Felipe Lessa felipe.le...@gmail.com wrote:
On Tue, Sep 28, 2010 at 10:41 AM, Peter Robinson thaldy...@gmail.com wrote:
readTVarIO :: TVar a - IO a
One needs to know if it is ok to wrap this IO action into an STM
action. For example,
data I a = I a
On Tue, Sep 28, 2010 at 11:01 AM, Antoine Latter aslat...@gmail.com wrote:
Isn't there an 'unsafeIOToSTM' function somewhere? Something like:
unsafeIOToSTM (IO k) = STM k
Then you might not need the case statement.
I thought there was, but I couldn't find it in the 'stm' package [1],
using
On Tue, Sep 28, 2010 at 9:05 AM, Felipe Lessa felipe.le...@gmail.com wrote:
On Tue, Sep 28, 2010 at 11:01 AM, Antoine Latter aslat...@gmail.com wrote:
Isn't there an 'unsafeIOToSTM' function somewhere? Something like:
unsafeIOToSTM (IO k) = STM k
Then you might not need the case statement.
Thanks for the responses, but I think I should explain a bit more.
I'm not interested in being able to read the live value of a TVar at
any arbitrary time (via. unsafeIOToSTM). But rather I would like
looslyReadTVar to have exactly the same semantics as readTVar, except
that the STM runtime would
2010/9/29 Tom Hawkins tomahawk...@gmail.com:
In the embedded domain, this could be a fault monitor that
reads a bunch of constantly changing sensors.
I think that sensor reading belongs to IO, not STM.
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On Tue, Sep 28, 2010 at 6:44 PM, Serguey Zefirov sergu...@gmail.com wrote:
2010/9/29 Tom Hawkins tomahawk...@gmail.com:
In the embedded domain, this could be a fault monitor that
reads a bunch of constantly changing sensors.
I think that sensor reading belongs to IO, not STM.
Sensors would
On Sep 28, 2010, at 6:36 PM, Tom Hawkins tomahawk...@gmail.com wrote:
Thanks for the responses, but I think I should explain a bit more.
I'm not interested in being able to read the live value of a TVar at
any arbitrary time (via. unsafeIOToSTM). But rather I would like
looslyReadTVar to have
On Tue, Sep 28, 2010 at 9:19 PM, Brandon Moore
brandon_m_mo...@yahoo.com wrote:
On Sep 28, 2010, at 6:36 PM, Tom Hawkins tomahawk...@gmail.com wrote:
Thanks for the responses, but I think I should explain a bit more.
I'm not interested in being able to read the live value of a TVar at
any
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