On 10/27/05, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote:
Tomasz Zielonka wrote:
Speaking about casts, I was playing with using GADTs to create a
non-extensible version of Data.Typeable and Data.Dynamic.
I wonder if it's possible to write such a thing without GADTs (and
unsafeCoerce,
Yeah, I was also thinking of impredicative types and that they would
make this problem go away. First of all, we may need to wait a while for
such types to become available in Haskell, but Daan has good stuff at
avail.
Also, for clarity, let me just point out that this is really about an
Udo Stenzel wrote:
That raises the question: Should combining functions on containers be
provided in a strict variant? Should strict application be the default?
With the exception of lists, I generally tend to want strict behavior
for collections. Combined with the principle of least
Scherrer, Chad wrote:
Sorry to drag this thread out, but here's one more thing you might
try...
(This is the café, isn't it? :-)
Another option is perhaps to pack both char and count in one Int and use
some kind of Set.
This should save some space, and possibly time as well (presuming
Actually, I think I was just hitting the top range of FD_SETSIZE,
about 8000 on that machine.
Does FD_SETSIZE get hardcoded into ghc-built binaries? That is if I
increase the available descriptors per process with uname -n, will it
be taken into account?
Thanks, Joel
On Oct 26,
I believe it does.
On Oct 26, 2005, at 1:32 AM, Donald Bruce Stewart wrote:
Does the code work when you compile it, instead of running it inside
ghci?
--
http://wagerlabs.com/
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Folks,
Does anyone have QuickCheck examples they could send me?
Also, how can I check Word32, Word64, etc. properties? It looks like
the built-in random generator only works with Int values and for the
life of me I cannot figure out how to extend it.
Last but not least, I'm trying to
On 10/27/05, Joel Reymont [EMAIL PROTECTED] wrote:
Folks,
Does anyone have QuickCheck examples they could send me?
Also, how can I check Word32, Word64, etc. properties? It looks like
the built-in random generator only works with Int values and for the
life of me I cannot figure out how to
Joel Reymont [EMAIL PROTECTED] writes:
Does anyone have QuickCheck examples they could send me?
There's a minimal introduction to QuickCheck and HUnit in the most recent issue
of The Monad.Reader: http://www.haskell.org/tmrwiki/IssueFive
Also, how can I check Word32, Word64, etc. properties?
Tom Hawkins wrote:
In a pure language, is it possible to detect cycles in recursive data
structures? For example, is it possible to determine that cyclic has
a loop? ...
data Expr = Constant Int | Addition Expr Expr
cyclic :: Expr
cyclic = Addition (Constant 1) cyclic
Or phased
Folks,
With lots of help from #haskell and haskell-cafe I came up with the
following setup. It's working fine but requires quite a bit of
boilerplate code. Could you please help me simplify it?
I apologize for the very long message and will describe any parts
that are unclear. Please ask
Would it cover the range between minBound :: Word32 and maxBound ::
Word32? I cannot figure out how to do this since maxBound :: Int32 is
less that that of Word32.
Also, I get the following error with ghci -fglasgow-exts
foo.hs:7:52: parse error on input `.'
--
module Foo where
import
Is this gonna be in the next version of QuickCheck? Or can it be
implemented now?
On Oct 27, 2005, at 3:47 PM, Shae Matijs Erisson wrote:
You can do that with the model based checking from the QuickCheckST
paper.
You could either generate actions and results and test separately,
or you
Hi,
so I'm a newbie getting used to Haskell. I'm writing some
simple things like genetic algorithms in it for practice,
and I keep coming across something that really bugs me:
are there any standard libraries that allow you to
do imperative style for or while loops using monads to keep
On Oct 27, 2005, at 11:01 AM, Joel Reymont wrote:Folks,With lots of help from #haskell and haskell-cafe I came up with the following setup. It's working fine but requires quite a bit of boilerplate code. Could you please help me simplify it?I apologize for the very long message and will describe
Creighton Hogg wrote:
Hi,
so I'm a newbie getting used to Haskell. I'm writing some
simple things like genetic algorithms in it for practice,
and I keep coming across something that really bugs me:
are there any standard libraries that allow you to
do imperative style for or while loops
Try this:
This line is before the loop
sequence_ $ replicate 10 $ do
line 1
line 2
...
last line
This line is after the loop
Now you can use shorthand via
loopN n block = sequence_ $ replicate n block
So that you can write:
This line is before the loop
loopN 10 $ do
line 1
line 2
Robert,
On Oct 27, 2005, at 4:59 PM, Robert Dockins wrote:
You could consider creating a monad for the unstuff part of the
operation that would hide dealing with the FastString, the tupling
and the case analysis on Maybe.
Could you elaborate on this a bit please? How would I write and use
Joel Reymont [EMAIL PROTECTED] writes:
I would very much like to see QuickCheckM extended to handle IO directly.
I've wanted to use QuickCheck to test TCP/IP stacks for unhandled cases.
Think of the entertainment value :-)
Is this gonna be in the next version of QuickCheck? Or can it be
Something else just occurred to me... How would I represent no
command using the Unstuff monad? I'm returning Maybe Command right
now, would this change?
On Oct 27, 2005, at 4:59 PM, Robert Dockins wrote:
You could consider creating a monad for the unstuff part of the
operation that would
On Oct 27, 2005, at 11:54 AM, Creighton Hogg wrote:
Hi,
so I'm a newbie getting used to Haskell. I'm writing some
simple things like genetic algorithms in it for practice,
and I keep coming across something that really bugs me:
are there any standard libraries that allow you to
do imperative
On 27/10/05, Joel Reymont [EMAIL PROTECTED] wrote:
On Oct 27, 2005, at 4:59 PM, Robert Dockins wrote:
[snip]
As a side note, I see you are doing a bunch of operations on lists
of properties. If performance is an issue, you might want to
consider using Data.Map or similar. If your
Lennart Augustsson wrote:
Tom Hawkins wrote:
In a pure language, is it possible to detect cycles in recursive data
structures? For example, is it possible to determine that cyclic
has a loop? ...
data Expr = Constant Int | Addition Expr Expr
cyclic :: Expr
cyclic = Addition (Constant 1)
Creighton Hogg wrote:
Hi,
so I'm a newbie getting used to Haskell. I'm writing some
simple things like genetic algorithms in it for practice,
and I keep coming across something that really bugs me:
are there any standard libraries that allow you to
do imperative style for or while loops
On 10/27/05, Joel Reymont [EMAIL PROTECTED] wrote:
Would it cover the range between minBound :: Word32 and maxBound ::
Word32? I cannot figure out how to do this since maxBound :: Int32 is
less that that of Word32.
Also, I get the following error with ghci -fglasgow-exts
foo.hs:7:52: parse
On 10/27/05, Sebastian Sylvan [EMAIL PROTECTED] wrote:
On 10/27/05, Joel Reymont [EMAIL PROTECTED] wrote:
Would it cover the range between minBound :: Word32 and maxBound ::
Word32? I cannot figure out how to do this since maxBound :: Int32 is
less that that of Word32.
Also, I get the
How is this supposed to work? Does anyone have a simple explanation?
I could not understand how to define this for arbitraries of my
choosing and Shae seems to have defined coarbitrary = error Not
implemented :-).
Thanks, Joel
--
http://wagerlabs.com/
Tom Hawkins wrote:
Lennart Augustsson wrote:
Tom Hawkins wrote:
In a pure language, is it possible to detect cycles in recursive data
structures? For example, is it possible to determine that cyclic
has a loop? ...
data Expr = Constant Int | Addition Expr Expr
cyclic :: Expr
cyclic =
I came up with this but can it be done better? I'm wishing for
default class methods :-).
instance Arbitrary Word16 where
arbitrary = arbitraryBound
coarbitrary a = error Not implemented
instance Arbitrary Word32 where
arbitrary = arbitraryBound
coarbitrary a = error Not
Hello,
On 10/27/05, Tom Hawkins [EMAIL PROTECTED] wrote:
...
data Expr = Constant Int | Addition Expr Expr
cyclic :: Expr
cyclic = Addition (Constant 1) cyclic
...
And there is nothing that says that your definition of cyclic
will actually have a cycle in the implementation.
How about this?
class ArbitraryDefault a where {}
instance (Integral a, Bounded a, ArbitraryDefault a) = Arbitrary a where
arbitrary = arbitraryBound
coarbitrary a = error Not implemented
instance ArbitraryDefault Word16
instance ArbitraryDefault Word32
instance ArbitraryDefault
This requires
{-# OPTIONS_GHC -fallow-undecidable-instances #-}
but since I'm using -fglasgow-exts in a lot of places I'm wondering
if adding undecidable instances would be a bad habit. I guess not...
not until I shoot myself in the foot :-).
Any explanation of undecidable instances, the
On Thu, 27 Oct 2005, Creighton Hogg wrote:
On Thu, 27 Oct 2005, Robert Dockins wrote:
On Oct 27, 2005, at 11:54 AM, Creighton Hogg wrote:
Hi,
so I'm a newbie getting used to Haskell. I'm writing some
simple things like genetic algorithms in it for practice,
and I keep
I've not had any problems with them, though of course your mileage may
vary. Have a look at section 7.4.4.3 in
http://www.haskell.org/ghc/docs/latest/html/users_guide/type-extensions.html#multi-param-type-classes
for an explanation. Basically, if you have a cyclic class dependency
graph, the
On Thu, 27 Oct 2005, Shae Matijs Erisson [EMAIL PROTECTED] wrote:
Joel Reymont [EMAIL PROTECTED] writes:
I could not understand how to define this for arbitraries of my
choosing and Shae seems to have defined coarbitrary = error Not
implemented :-).
Coarbitrary is for generator
On Thu, 27 Oct 2005, Sebastian Sylvan [EMAIL PROTECTED] wrote:
instance Arbitrary Word32 where
arbitrary = do c - arbitrary :: Gen Integer
return (fromIntegral c)
This definition will usually only generate very small or very large
Word32 values. The reason is the wrapping
Why is it that everything that OO steals from the functional
paradigm is always marketed as something new that will revolution the
way we program? Can't they at least give some credit where credit is
due? :-p
Because mentioning FP is the kiss of death?
-- Lennart
PS. I can see Eric Meijer's shadow behind this. ;)
Niklas Broberg wrote:
Why is it that everything that OO steals from the functional
paradigm is always marketed as something new that will revolution the
way we program? Can't
On Thu, 27 Oct 2005, Lennart Augustsson [EMAIL PROTECTED] wrote:
Tom Hawkins wrote:
Or phased differently, is it possible to make Expr an instance of
Eq such that cyclic == cyclic is smart enough to avoid a recursive
decent?
No. And there is nothing that says that your definition of
Hello Tom,
Thursday, October 27, 2005, 6:46:41 PM, you wrote:
TH In a pure language, is it possible to detect cycles in recursive data
TH structures?
no, but it is possible in GHC. Einar Karttunen in his SerTH - Binary
Serialization library for Haskell used makeStableName and
unsafeCoerce# to
Hello Creighton,
Thursday, October 27, 2005, 7:54:22 PM, you wrote:
CH Haskell seems to me to be a very powerful language, and it
CH looks like it should be possible to define control
CH structures such as for loops using monads.
it's my own lib:
-- |Conditional execution
whenM cond action =
On Thursday 27 October 2005 10:29, Ketil Malde wrote:
Scherrer, Chad wrote:
Sorry to drag this thread out, but here's one more thing you might
try...
(This is the café, isn't it? :-)
Another option is perhaps to pack both char and count in one Int and
use some kind of Set.
This should
Hi,
Hugs leaves an odd context when showing the type of the following
expression. Is this a bug or just a harmless flaw?
Christian
Hugs.Base :t toRational 1 / 2
toRational 1 / 2 :: Real a = Ratio Integer
ghci yields:
Prelude :t toRational 1 / 2
interactive:1:0:
Warning: Defaulting the
Just one more question...
data Prop = forall a b. (Eq a, Eq b, Show a, Packet b, Convertible a b)
= Attr a b := a
deriving (Typeable)
data Attr a b = Attr String
(a - Dynamic, Dynamic - Maybe a)
(a - b, b - a)
makeAttr :: (Typeable a, Convertible a b) = String - Attr a b
On Thu, Oct 27, 2005 at 11:02:48PM +0200, Christian Maeder wrote:
Hugs.Base :t toRational 1 / 2
toRational 1 / 2 :: Real a = Ratio Integer
ghci yields:
Prelude :t toRational 1 / 2
interactive:1:0:
Warning: Defaulting the following constraint(s) to type `Integer'
`Real
This compiles:
instance (Typeable a, Arbitrary a, Typeable b, Arbitrary b,
Convertible a b) = Arbitrary (Attr a b) where
arbitrary = makeAttr `fmap` arbitrary
coarbitrary a = error Not implemented
arbitraryProp :: forall a b.(Eq a, Packet b, Show a, Convertible a b,
Arbitrary a,
On Thu, Oct 27, 2005 at 07:06:12PM +0100, Joel Reymont wrote:
This requires
{-# OPTIONS_GHC -fallow-undecidable-instances #-}
but since I'm using -fglasgow-exts in a lot of places I'm wondering
if adding undecidable instances would be a bad habit. I guess not...
not until I shoot
On Thu, Oct 27, 2005 at 09:31:51PM +0200, Lennart Augustsson wrote:
Because mentioning FP is the kiss of death?
eh, no worse than mentioning cold fusion. :)
John
--
John Meacham - ⑆repetae.net⑆john⑈
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