I've read 4 messages following this, but I'd like to pursue this a little
to test my own understanding...
At 14:12 30/12/03 +, Joe Thornber wrote:
I was wondering if anyone could give me some help with this problem ?
I'm trying to hold some state in a StateMonad whilst I iterate over a
large
On Wed, Dec 31, 2003 at 11:54:27AM +, Graham Klyne wrote:
> My *intuition* here is that the problem is with countLeaves2, in that it
> must build the computation for the given [sub]tree before it can start to
> evaluate it. Maybe this is why other responses talk about changing the
> state m
At 12:36 31/12/03 +, Joe Thornber wrote:
On Wed, Dec 31, 2003 at 11:54:27AM +, Graham Klyne wrote:
> My *intuition* here is that the problem is with countLeaves2, in that it
> must build the computation for the given [sub]tree before it can start to
> evaluate it. Maybe this is why other r
On Wed, Dec 31, 2003 at 02:38:06PM +, Graham Klyne wrote:
> getOrCachePositionValue pos =
> do { mcache <- gets (findPos pos) -- Query cache for position
>; case mcache of
>Just cached -> return (cachedVal cached) -- Return cached value
>Nothing ->
Hi,
Can anyone explain to me how hugs manages to derive that
f x y z = y (y z) x
is of type
f :: a -> ((a -> b) -> a -> b) -> (a -> b) -> b
Many thanks and a happy new year to all!
Lee
_
Stay in touch with absent friends - get M
On 2003-12-31 at 19:27GMT "Lee Dixon" wrote:
> Hi,
>
> Can anyone explain to me how hugs manages to derive that
>
> f x y z = y (y z) x
>
> is of type
>
> f :: a -> ((a -> b) -> a -> b) -> (a -> b) -> b
To begin with, f has three arguments, x y and z, so letting
each of these have types Tx Ty
Omitting the typeclass bit, I'm trying to write something like
(s1 -> s2) -> StateT s1 m () -> StateT s2 m a -> StateT s1 m a
That is, it sequences two StateT computations, providing a way to
translate from the first's state to the second to keep the chain
going.
I can easily write something for
I tried posting this before but, from my point of view, it vanished. My
apologies if it's a duplicate.
In http://www.cs.uu.nl/~daan/download/parsec/parsec.html we read,
> testOr2 = try (string "(a)")
> <|> string "(b)"
>
> or an even better version:
>
> testOr3 = do{ try (string "(a")
Mark,
I'm no expert, but does it help to start from withStateT?
> withStateT :: (s -> s) -> StateT s m a -> StateT s m a
> withStateT f m = StateT $ runStateT m . f
There are some notes about computations and lifting
state transformers in
Modular Denotational Semantics for Compiler Construction
Mark Carroll <[EMAIL PROTECTED]> wrote in article <[EMAIL PROTECTED]> in
gmane.comp.lang.haskell.cafe:
> Omitting the typeclass bit, I'm trying to write something like
> (s1 -> s2) -> StateT s1 m () -> StateT s2 m a -> StateT s1 m a
>
> That is, it sequences two StateT computations, providing a w
On Wed, 31 Dec 2003, Ken Shan wrote:
> Don't you need a (s2 -> s1) function as well, to translate the final
> state back into StateT s1?
Yes, you're right: the thing actually running the stateful computation
presumably expects to start it with a state of type s1 and to be able to
extract from it
11 matches
Mail list logo
