Hi,
How do I include type families (used as associated
types) in a module export list? E.g.:
class MyClass a where
type T a :: *
coolFunction :: Ta - a
(...)
If I just include MyClass and its functions in the
list, instances in other modules complain they don't
know T, but I wasn't
wren ng thornton wrote:
(Though it doesn't necessarily generalize to cover similar messages like:
Prelude :t (\x - x) :: a - b
interactive:1:7:
Couldn't match expected type `b' against inferred type `a'
`b' is a rigid type variable bound by
the polymorphic
I find this slightly more complicated case quite confusing with the
current wording:
Prelude :t (\x - x) :: (a - b) - (a - a)
interactive:1:7:
Couldn't match expected type `a' against inferred type `b'
`a' is a rigid type variable bound by
an expression type
On Saturday 30 May 2009 03:10:11 Bryan O'Sullivan wrote:
On Fri, May 29, 2009 at 5:04 PM, Bartosz Wójcik bar...@sudety.it wrote:
I don't undersdand what is being missed.
Brevity.
liftM f m1 = do { x1 - m1; return (f x1) }
so
liftM fromIntegral integer
will result the
Try http://sites.google.com/site/haskell/notes/connecting-to-mysql-with-haskell
that I wrote up. An important thing that I don't think was documented
anywhere is that the trailing ';' is required.
On Fri, May 29, 2009 at 11:01 PM, Michael P Mossey
m...@alumni.caltech.edu wrote:
I'm trying to use
On Sat, May 30, 2009 at 7:35 PM, Maurício briqueabra...@yahoo.com wrote:
Hi,
How do I include type families (used as associated
types) in a module export list? E.g.:
class MyClass a where
type T a :: *
coolFunction :: Ta - a
(...)
If I just include MyClass and its functions in
2009/05/30 Bartosz Wójcik bar...@sudety.it:
...reading RWH I could not memorize what those liftM funtions
meant.
The basic one, `liftM`, means `fmap`, though specialized for
functors that are monads.
Prelude Control.Monad :t liftM
liftM :: forall a b (m :: * - *). (Monad m) = (a -
On Sat, May 30, 2009 at 1:12 PM, Jason Dusek jason.du...@gmail.com wrote:
2009/05/30 Bartosz Wójcik bar...@sudety.it:
...reading RWH I could not memorize what those liftM funtions
meant.
The basic one, `liftM`, means `fmap`, though specialized for
functors that are monads.
Prelude
Hi how could one implement a function in concurrent haskell that either
returns 'a' successfully or due timeout 'b'?
timed :: Int → IO a → b → IO (Either a b)
timed max act def = do
Best Regards,
Cetin Sert
___
Haskell-Cafe mailing list
The following code is from Section 8.4.2, pgs. 111-112 (PDF paging) of YAHT.
It compiles fine, but upon trying it I get the following error message.
It seems to be trying to 'Show' the Computation class but I'm not sure where to
put the 'Deriving'.
Michael
Loading package
2009/5/30 Cetin Sert cetin.s...@gmail.com
Hi how could one implement a function in concurrent haskell that either
returns 'a' successfully or due timeout 'b'?
timed :: Int → IO a → b → IO (Either a b)
timed max act def = do
Something like (warning, untested code - no compiler atm).
timed
Thank you for your reply, I'd come up with the following:
timed :: Int → IO a → b → IO (Either b a)
timed max act def = do
r ← new
t ← forkIO $ do
a ← act
r ≔ Right a
s ← forkIO $ do
wait max
e ← em r
case e of
True → do
kill t
r ≔ Left def
On Sat, May 30, 2009 at 10:32 PM, Cetin Sert cetin.s...@gmail.com wrote:
Thank you for your reply, I'd come up with the following:
timed :: Int → IO a → b → IO (Either b a)
timed max act def = do
r ← new
t ← forkIO $ do
a ← act
r ≔ Right a
s ← forkIO $ do
wait max
It's trying to 'Show' the 'c [Int]' type, but doesn't know which 'c'
to use; so it's trying to find a generic instance, which doesn't
exist. You can't fix this with 'deriving' or anything like this;
instead, provide the type annotation like this:
*Main searchAll g 1 3 :: Maybe [Int]
On 31
michael rice nowg...@yahoo.com writes:
The following code is from Section 8.4.2, pgs. 111-112 (PDF paging) of YAHT.
It compiles fine, but upon trying it I get the following error message.
It seems to be trying to 'Show' the Computation class but I'm not sure where
to put the 'Deriving'.
My
The proper way is just to wrap System.Timeout, which does some rather
clever things with regards to exception semantics. The code for it is
a joy to read, by the way.
--S.
On May 30, 2009, at 5:36 PM, Sebastian Sylvan wrote:
On Sat, May 30, 2009 at 10:32 PM, Cetin Sert
Hi,
I want to move one object to the border of window, then go back to the start
point. Does anyone one have an idea to implement it ? Thank you!
___
好玩贺卡等你发，邮箱贺卡全新上线！
Dear Doaitse,
It is my pleasure to announce that after 5 days of experimenting with
uu-parsinglib I have absolutely no clue, whatsoever, on how to use it.
Period.
I do not even manage to write a parser for even a mere digit or a simple
character. I have read the tutorial from a to a to z
-__- hehe why did I not let Hayoo or Hoogle help me there *sigh*
Thanks!!
2009/5/31 Sterling Clover s.clo...@gmail.com
The proper way is just to wrap System.Timeout, which does some rather
clever things with regards to exception semantics. The code for it is a joy
to read, by the way.
--S.
On Fri, May 29, 2009 at 5:36 AM, Max Rabkin max.rab...@gmail.com wrote:
On Fri, May 29, 2009 at 12:29 PM, Paul Keir pk...@dcs.gla.ac.uk wrote:
f''' = ([]::[()]) == ([]::[()])
(Very pretty.)
So why doesn't ghc have 'default' instances?
It does. I believe Num defaults to Integer and then to
Hello!
Why isn't there an option to control whether HPC, the Haskell
Program Coverage, will consider derived instances coverable.
I'm using it and my top level coverage is 52% while my expression
coverage is at 92%. Looking carefully we see that most
non-tested top level definitions are derived
Hi Miguel,
That works. but it gives just a single solution [1,2,3] when there are supposed
to be two [[1,2,3],[1,4,3]]. Of course the code in YAHT may be in error.
Also, how the heck does Haskell decide which success, failure, augment,
and combine to use in function searchAll, since there are
On Sat, May 30, 2009 at 9:00 PM, michael rice nowg...@yahoo.com wrote:
That works. but it gives just a single solution [1,2,3] when there are
supposed to be two [[1,2,3],[1,4,3]]. Of course the code in YAHT may be in
error.
Works for me.
*Main searchAll g 1 3 :: [[Int]]
[[1,2,3],[1,4,3]]
On Sat, May 30, 2009 at 6:33 PM, David Menendez d...@zednenem.com wrote:
*Main :t searchAll
searchAll :: (Computation c) = Graph t t1 - Int - Int - c [Int]
The way searchAll is written, the choice of which functions to use
depends on the type variable c. That's determined by the calling
I figured out the [[Int]] case for myself, but hadn't considered the Failure
case. Thanks.
In function searchAll, given a calling context Failable [Int], for the line
where search' [] = failure no path
failure would be Fail, a constructor that takes a String. Right?
But using either of
Belay that last question. I just realized that its the const function being
used rather than a constant declaration in const Nothing and const [].
MIchael
--- On Sat, 5/30/09, David Menendez d...@zednenem.com wrote:
From: David Menendez d...@zednenem.com
Subject: Re: [Haskell-cafe] Missing a
Hi Ryan,
Is there something missing or mislabeled in your post, because I don't see any
definition of toDynamic.
Michael
--- On Sun, 5/31/09, Ryan Ingram ryani.s...@gmail.com wrote:
From: Ryan Ingram ryani.s...@gmail.com
Subject: Re: [Haskell-cafe] Missing a Deriving?
To: David Menendez
Oops, it's called toDyn; from Data.Dynamic [1]
toDyn :: Typeable a = a - Dynamic
-- ryan
[1] http://haskell.org/ghc/docs/latest/html/libraries/base/Data-Dynamic.html
On Sat, May 30, 2009 at 10:18 PM, nowg...@yahoo.com wrote:
Hi Ryan,
Is there something missing or mislabeled in your
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