On 19 May 2009, at 09:06, Ryan Ingram wrote:
This is a common problem with trying to use do-notation; there are
some cases where you can't make the object an instance of Monad. The
same problem holds for Data.Set; you'd can write
setBind :: Ord b = Set a - (a - Set b) - Set b
setBind m f =
I'm writing a paper as a replacement for writing exam and decided to write
a simple compiler (got a little experience with it). However, I got trouble
in parsing expression.
The grammar:
expression = get | [ + | - ] term { ( + | - ) term }
term = factor { ( * | / ) factor }
factor =
2009/05/18 Miguel Mitrofanov miguelim...@yandex.ru:
On 19 May 2009, at 09:06, Ryan Ingram wrote:
This is a common problem with trying to use do-notation; there are
some cases where you can't make the object an instance of Monad. The
same problem holds for Data.Set; you'd can write
setBind
On Mon, May 18, 2009 at 10:06 PM, Ryan Ingram ryani.s...@gmail.com wrote:
On Mon, May 18, 2009 at 3:05 PM, Taral tar...@gmail.com wrote:
Will this do?
(=) :: (NFData sa, NFData b) = LI sa - (sa - LI b) - LI b
No, the problem is that = on monads has no constraints, it must have the
type
LI
On May 19, 2009, at 01:42 , Jason Dagit wrote:
I've often seen this bit of scary code in VB:
Dim i as Integer = 5
If i = 5 Then
' Do something, because 5 = 5
End If
Sure, that works in Perl too. But the equivalent case here would be
chr$(5), not 5.
--
brandon s. allbery
On May 18, 2009, at 15:28 , Claus Reinke wrote:
My current best try uses the uvector package, has two 'vectors' of
type
(UArr Double) as input, and relies on the sumU and zipWithU
functions
which use streaming to compute the result:
dist_fast :: UArr Double - UArr Double - Double
On May 18, 2009, at 20:54 , Claus Reinke wrote:
As I said, I don't get the fusion if I just add the function above
to the original Dist.hs, export it and compile the module with '-c
-O2 -ddump-simpl':
I can't reproduce this.
Interesting. I'm using ghc 6.11.20090320 (windows),
On Mon, 18 May 2009, Nicolas Pouillard wrote:
Excerpts from Jason Dusek's message of Sun May 17 15:45:25 +0200 2009:
From the documentation:
LI could be a strict monad and a strict applicative functor.
However it is not a lazy monad nor a lazy applicative
functor as required
The grammar:
expression = get | [ + | - ] term { ( + | - ) term }
term = factor { ( * | / ) factor }
factor = IDENTIFIER | VALUE | ( expression )
I can't make term parse, for instance 1 * 2 / 3
Indeed, the grammar does not admit 1*2/3 as a sentence of that
language although it
Could either of those approaches (FRP / Delimited Continuations) be a
solution for implementing complex GUI code?
I think the answer is generally yes; I have tried writing a user
interface which has a form with several controls; a change in one
control may affect all other controls on the form
Excerpts from Taral's message of Tue May 19 00:05:39 +0200 2009:
On Mon, May 18, 2009 at 10:30 AM, Nicolas Pouillard
nicolas.pouill...@gmail.com wrote:
The type I would need for bind is this one:
(=) :: NFData sa = LI sa - (sa - LI b) - LI b
Will this do?
(=) :: (NFData sa, NFData
Indeed, the grammar does not admit 1*2/3 as a sentence ...
Huh? Why not? 1 * 2 / 3 should match factor * factor / factor.
Remember that { } is repetition, so it should be able to handle such term.
expression ::= term | term + expression
term ::= factor | factor * term
factor ::= constant |
To be fair, you can do this with some extensions; I first saw this in
a paper on Oleg's site [1]. Here's some sample code:
{-# LANGUAGE NoImplicitPrelude, TypeFamilies, MultiParamTypeClasses #-}
module SetMonad where
import qualified Data.Set as S
import qualified Prelude as P (Monad, (=), (),
I've posted it once or twice.
newtype C m r a = C ((a - m r) - m r)
It's a monad, regardless of whether m is one or not. If you have something like return and bind, but not exactly the same, you can make
casting functions
m a - C m r a
and backwards.
Jason Dusek wrote on 19.05.2009 10:23:
Excerpts from Ryan Ingram's message of Tue May 19 10:23:01 +0200 2009:
To be fair, you can do this with some extensions; I first saw this in
a paper on Oleg's site [1]. Here's some sample code:
This seems like the same trick as the rmonad package:
Minor addition, optimize
(I couldn't help myself!)
-- ryan
instance Ord b = ConstrainedBind (S.Set a) (S.Set b) where
type BindElem (S.Set a) = a
m = f = S.unions $ map f $ S.toList m
m n = if S.null m then S.empty else n
___
Why is Symbol = (String, Token)? A more sensible token type would
include values in the Value constructor and string identifiers in the
Identifier constructor; the strings in everything else seem redundant.
A more pure/monadic parser would have a type like this:
data Result a = Error String |
Nicolas Pouillard wrote:
Excerpts from Ryan Ingram's message of Tue May 19 10:23:01 +0200 2009:
To be fair, you can do this with some extensions; I first saw this in
a paper on Oleg's site [1]. Here's some sample code:
This seems like the same trick as the rmonad package:
Why is Symbol = (String, Token)? A more sensible token type would
include values in the Value constructor and string identifiers in the
Identifier constructor; the strings in everything else seem redundant.
Surely you didn't read my original post, do you? I have a very limited
knowledge of
On Tue, May 19, 2009 at 12:54 AM, Miguel Mitrofanov
miguelim...@yandex.ru wrote:
I've posted it once or twice.
newtype C m r a = C ((a - m r) - m r)
It's a monad, regardless of whether m is one or not. If you have something
like return and bind, but not exactly the same, you can make casting
Am Samstag, 16. Mai 2009 16:18 schrieb Günther Schmidt:
Hi all,
In my app, there is one part which has a rather complicated GUI logic,
it involves n drop downs with n choices each.
Whenever the current selection in one of the drop downs changes by user
interaction, the other (n-1) drop
These QuickCheck properties don't really test your sort function.
The `a' type variable will be instantiated to ().
So you will test with lists of units, like so:
ghci quickCheck (\xs - isSorted (reverse xs))
OK, passed 100 tests.
This can be simply solved by added a more specific type
Surely you didn't read my original post, do you? I have a very limited
knowledge of Monad and I try to find a solution using my current skills
because the due date is within two weeks. Therefore, I don't think I can
create a Monadic parser for this.
I think you're giving up way too easily.
I hope you're right. 7 pages... 1-2 nights should be enough. Thanks for all.
--
View this message in context:
http://www.nabble.com/Expression-parsing-problem-tp23610457p23614011.html
Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.
Hello!
On Monday 18 May 2009 14:37:51 Kenneth Hoste wrote:
I'm mostly interested in the range 10D to 100D
is the dimension known at compile-time? Then you could consider Template
Haskell. I wrote up some code for generating the vector types and vector
subtraction/inner product below, HTH. One
I understand from your later post that is was in fact specialized, but
how do I make sure it _is_ specialized?
-ddump-tc seems to give the generalized type, so it seems you'd need
to look at the -ddump-simpl output if you want to know whether a
local function is specialized.
Hi,
meh, I just realised that there is no sensible way to actually
introduce/eliminate the generated types. I'm attaching a revised version with
fromList/toList functions. Maybe the vector type should be polymorphic and be
an instance of Functor, Monad and Foldable? But then we really depend
Hello,
2009/5/19 leledumbo leledumbo_c...@yahoo.co.id:
expression ::= term | term + expression
term ::= factor | factor * term
factor ::= constant | variable | ( expression )
Oh, left recursion. Well, it should be easy to transform:
expression ::= term | moreTerm
term ::= factor |
On May 19, 2009, at 13:24 , Daniel Schüssler wrote:
Hello!
On Monday 18 May 2009 14:37:51 Kenneth Hoste wrote:
I'm mostly interested in the range 10D to 100D
is the dimension known at compile-time? Then you could consider
Template
Haskell.
In general, no. :-)
It will be known for
Thanks.
I had put together something similar to your first suggestion but tried to use
PutStrLn(Show...). I'd also thought of your second suggestion about a dummy
show for functions.
A little further along in The Little MLer the ints function is replaced by
other functions like primes and
Cool!
Is there *anything* Haskell *can't* do?
Michael
--- On Mon, 5/18/09, David Menendez d...@zednenem.com wrote:
From: David Menendez d...@zednenem.com
Subject: Re: [Haskell-cafe] showing a user defined type
To: Ryan Ingram ryani.s...@gmail.com
Cc: haskell-cafe@haskell.org
Date: Monday, May
On Tue, May 19, 2009 at 8:46 AM, Brandon S. Allbery KF8NH
allb...@ece.cmu.edu wrote:
On May 19, 2009, at 01:42 , Jason Dagit wrote:
I've often seen this bit of scary code in VB:
Dim i as Integer = 5
If i = 5 Then
' Do something, because 5 = 5
End If
Sure, that works in Perl too.
That's
Hi Justin,
I updated my changes to apply against that repo, thanks for
the pointer. Cool to see new changes to haskelldb, especially
all the new unit tests!
You can find my updated repo at:
http://patch-tag.com/r/haskelldb-hlist
Re-reading your email now, I see you asked for a patch, but
michael rice wrote on 19.05.2009 18:16:
Cool!
Is there *anything* Haskell *can't* do?
Well, I haven't found a way to emulate polymorphics kinds yet, and I feel like
I need them. Other than than - probably no.
Michael
--- On *Mon, 5/18/09, David Menendez /d...@zednenem.com/* wrote:
main = interact (unlines . lines)
This *appears* to somewhat reliably get me functionality that looks like
take a line of input, and print it out.
Is this behavior something I can rely on working?
I like the idea that lines can pull lines lazily from getContents which
lazily consume the input.
2009/05/19 David Leimbach leim...@gmail.com:
...I'm concerned that relying on a pure function like
unlines . lines to sequence IO is a bit too implicit in nature.
You aren't relying on `unlines . lines` to do the sequencing;
you're relying on them to process a string. That the
characters
On Tue, May 19, 2009 at 7:07 AM, michael rice nowg...@yahoo.com wrote:
A little further along in The Little MLer the ints function is replaced by
other functions like primes and fibs, which also return Links:
fun primes(n)
= if is_prime(n+1)
then Link(n+1,primes)
else primes(n+1)
fun
David Leimbach leim...@gmail.com wrote:
main = interact (unlines . lines)
This *appears* to somewhat reliably get me functionality that looks like
take a line of input, and print it out.
Is this behavior something I can rely on working?
I like the idea that lines can pull lines lazily from
Hi,
I have ghc 6.10.1 and gtk2hs 0.10.0 installed on my windows vista
computer. Both were installed using the installer on the webpages.
I am able to use gtk, glade etc but not sourceview or cairo. If I
compile the examples in the gtk2hs example folder, I get not in
scope error messages for
Hi Kenneth,
I wrote a benchmark similar to yours using the haskell blas library I
wrote (latest version is on github at http://github.com/patperry/blas/tree/master
, an older version is on hackage).
The pure Haskell implementation is not very good, and the problem
seems to be repeated
From: Eugene Kirpichov ekirpic...@gmail.com
Date: Sun, 17 May 2009 23:10:12 +0400
Is there any research on applying free theorems / parametricity to
type systems more complex than System F; namely, Fomega, or calculus
of constructions and alike?
You may be interested in this:
The Theory of
Hi Ryan,
I'm afraid you've lost me. Maybe if you showed how this would be used in ML I
would get the picture.
Michael
--- On Tue, 5/19/09, Ryan Ingram ryani.s...@gmail.com wrote:
From: Ryan Ingram ryani.s...@gmail.com
Subject: Re: [Haskell-cafe] showing a user defined type
To: michael rice
Anybody else around here?
Best,
Maurício
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Hi, friends
rollDice :: Word8 - IO Word8
rollDice n = do
bracket (openFile /dev/random ReadMode) (hClose)
(\hd - do v - fmap B.unpack (B.hGet hd 1)
let v1 = Data.List.head v
return $ (v1 `mod` n) + 1)
.
blueIdx - rollDice $ length [1..33]
On Wed, May 20, 2009 at 08:40:15AM +0800, z_a...@163.com wrote:
I know length [1..33] is Int not Word8, but Word8 is enough here.
Just saying '33' is enough here. :)
--
Felipe.
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Not exactly São Carlos: São Paulo - SP.
On Tue, May 19, 2009 at 09:28:55PM -0300, Maurício wrote:
Anybody else around here?
Best,
Maurício
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2009/5/20 z_a...@163.com z_a...@163.com:
Hi, friends
rollDice :: Word8 - IO Word8
rollDice n = do
bracket (openFile /dev/random ReadMode) (hClose)
(\hd - do v - fmap B.unpack (B.hGet hd 1)
let v1 = Data.List.head v
return $ (v1 `mod` n) + 1)
On May 19, 2009, at 10:20 , Chaddaï Fouché wrote:
On Tue, May 19, 2009 at 8:46 AM, Brandon S. Allbery KF8NH
allb...@ece.cmu.edu wrote:
On May 19, 2009, at 01:42 , Jason Dagit wrote:
I've often seen this bit of scary code in VB:
Dim i as Integer = 5
If i = 5 Then
' Do something, because 5 = 5
On Wed, May 20, 2009 at 3:40 AM, z_a...@163.com z_a...@163.com wrote:
Hi, friends
rollDice :: Word8 - IO Word8
rollDice n = do
bracket (openFile /dev/random ReadMode) (hClose)
(\hd - do v - fmap B.unpack (B.hGet hd 1)
let v1 = Data.List.head v
2009/5/20 Bernie Pope florbit...@gmail.com:
Oh right. I didn't see your proposal (did it get sent to the list?).
Yes, I just push the Replay button, not the
Sorry for the confusion.
It's my fault, sorry.
lee
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I've opened a ticket for this
(http://hackage.haskell.org/trac/ghc/ticket/3245), but someone else
will have to do the investigation into the problem.
Michael D. Adams
On Thu, May 14, 2009 at 10:59 AM, Simon Peyton-Jones
simo...@microsoft.com wrote:
Interesting. Would anyone care to make a Trac
Hi,
I've been writing some code to calculate the stretch factor of a tree
of points. What it means is that for every node in a tree (lets call
it 'pivot'), I have to traverse the same tree (lets call each node
'current') and sum d_t(pivot, current) / d(pivot, current) for each
node,
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