Hi Bulat!
On Aug 24, 2006, at 1:07 PM, Bulat Ziganshin wrote:
Hello Brian,
Thursday, August 24, 2006, 4:16:41 PM, you wrote:
I would make all the fields strict here, to be sure that no
lazyness can
creep about unseen eg:
data Tag s = Tag {
tagID :: !Int,
state ::
Hello Gregory,
Thursday, August 24, 2006, 4:43:57 PM, you wrote:
> I agree this should be a FAQ.
we already have something like this on performance/strictness
wikipage. although adding your example of misusing $! may be helpful -
peoples are always better learned on (good and bad) examples rathe
Hello Brian,
Thursday, August 24, 2006, 4:16:41 PM, you wrote:
> I would make all the fields strict here, to be sure that no lazyness can
> creep about unseen eg:
> data Tag s = Tag {
> tagID :: !Int,
> state :: !(STRef s TagState),
> count :: !(STRef s Integer)
>
Hi Udo,
On Aug 24, 2006, at 7:22 AM, Udo Stenzel wrote:
Hi Gregory,
Gregory Wright wrote:
step :: Tag s -> ST s (Maybe Integer)
step t = do
c <- readSTRef (count t)
s <- readSTRef (state t)
writeSTRef (count t) (c - 1)
writeSTRef (state t) (nextState s)
Hi Gregory,
Gregory Wright wrote:
> step :: Tag s -> ST s (Maybe Integer)
> step t = do
> c <- readSTRef (count t)
> s <- readSTRef (state t)
> writeSTRef (count t) (c - 1)
> writeSTRef (state t) (nextState s)
> if (c <= 0) then return Nothing else return (J
Hi Bulat,
On Aug 24, 2006, at 7:52 AM, Bulat Ziganshin wrote:
Hello Gregory,
Thursday, August 24, 2006, 2:29:15 PM, you wrote:
step t = do
c <- readSTRef (count t)
s <- readSTRef (state t)
writeSTRef (count t) (c - 1)
writeSTRef (state t) (nextState s)
Gregory Wright wrote:
-- A structure with internal state:
--
data Tag s = Tag {
tagID :: Int,
state :: STRef s TagState,
count :: STRef s Integer
}
data FrozenTag = FrozenTag {
ft_tagID :: Int,
ft_state :: TagState,
ft_count :: Integer
} deriving
Hello Gregory,
Thursday, August 24, 2006, 2:29:15 PM, you wrote:
> step t = do
> c <- readSTRef (count t)
> s <- readSTRef (state t)
> writeSTRef (count t) (c - 1)
> writeSTRef (state t) (nextState s)
> if (c <= 0) then return Nothing else return (Just
The write*Ref functions, like many "write into data structure" have the common
problem of being much lazier than you want. The nextState calls form a lazy
thunk. In fact it tries form 10^6 nested thunks to call nextState. So you have
to use something like seq to reduce the laziness:
step
Hi,
I have a program, abstracted from a larger application that I am
writing for a customer, that persistently overflows its stack. The
program is a simulation of the communication protocol of a
sensor tag. The code is below.
The program mimics a hardware state machine. In the example
below,
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