On Fri, 2007-05-04 at 20:02 +0400, Bulat Ziganshin wrote:
don't understand what this monad thingy is all about.
the whole monadic business was introduced with the sole goal to let
haskellers believe that they are smarter than other programmers :)
Or perhaps to ensure that they are?
-k
Andrew Coppin wrote:
[snip]
Fact #1: I don't *know* of any other numerical integration algorithm.
(I've heard of RK4, but it's too complicated for me to understand.)
higher-order runge-kutta algorithms typically have high integration
accuracy, but may require multiple energy/force evaluations
| The source code has explicit monomorphic types all over it; I would
| expect GHC to be able to optimise out any method calls. (OTOH, I'm not a
| GHC expert... Simon? Don?)
Full monomorphisation is a whole-program optimisation and GHC isn't (yet) a
whole-program compiler. Overloaded functions
| Type classes and GADTs are broken in all versions prior to HEAD (at
| which point Simon made a heroic effort to do something I don't quite
| understand to the type checker).
Well, not that heroic, but certainly long-postponed :-)
Simon
___
As someone mentioned, don't worry about being new to Haskell, but DO send your
messages to haskell-cafe@haskell.org, not the main Haskell list. I'm
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Simon
| -Original Message-
| From: [EMAIL PROTECTED]
This email is a .lhs.
{-# OPTIONS -fglasgow-exts #-}
{-# OPTIONS -fallow-undecidable-instances #-}
{-# OPTIONS -fallow-overlapping-instances #-}
Let's implement the Kleene * in the type system. First some phantom
types:
data At n
data Bt n
data Ct n
data Endt
Now a chain to hold it
Apologies for sending this twice. Mutt obviously outsmarted mailman and
put a useful mime type header in. Not so this one!
This email is a .lhs.
{-# OPTIONS -fglasgow-exts #-}
{-# OPTIONS -fallow-undecidable-instances #-}
{-# OPTIONS -fallow-overlapping-instances #-}
Let's implement the
Simon Peyton-Jones wrote:
| The source code has explicit monomorphic types all over it; I would
| expect GHC to be able to optimise out any method calls. (OTOH, I'm not a
| GHC expert... Simon? Don?)
Full monomorphisation is a whole-program optimisation and GHC isn't (yet) a
whole-program
On 06/05/07, Duncan Coutts [EMAIL PROTECTED] wrote:
Try the latest darcs version of c2hs, it has a new C parser which should
fix issues like this. We should have a new tarball release soon.
Works great. Thanks very much.
--
-David House, [EMAIL PROTECTED]
Call for Copy
The Monad.Reader - Issue 8
I would like to welcome articles for the next issue of The Monad.Reader.
* The Monad.Reader *
The Monad.Reader is a electronic magazine about all things Haskell.
It is less-formal than journal,
| What I'm trying to say is, I would have expected, say,
|
| resultant :: [Vector2] - Vector2
| resultant = sum
|
| to run faster than
|
| resultant = sum
|
| In the latter case, we have resultant :: (Num n) = [n] - n. I'm no
| expert, but I would expect that this requires a method lookup
| In the latter case, we have resultant :: (Num n) = [n] - n. I'm no
| expert, but I would expect that this requires a method lookup on each
| call, whereas with the more restrictive type I would expect the compiler
| to be able to just link directly to the correct method implementation.
| Am I
| Presumably changing it to resultant = foldl' (+) wouldn't help much either?
I think not.
| Seems to me there's always a tradeoff to be made between CPU time, RAM
| usage, and code size - if not other factors too. :-S But Haskell seems
| to be fairly unique in that (it looks like) it's possible
Hello Adrian,
Sunday, May 6, 2007, 12:24:27 PM, you wrote:
Are there any good books about intermediate to advanced Haskell? The
perhaps, Purely Functional Data Structures by Okasaki?
also, Applications of Functional Programming may be interesting
--
Best regards,
Bulat
Simon Peyton-Jones wrote:
| I guess I was assuming that a function like sum is simple enough to
| get inlined at the call site - and hence possibly optimised at that
| site. Apparently not.
There is no reason in principle why not. It's just that GHC doesn't do it at
the moment.
On one
On May 7, 2007, at 8:50 , Andrew Coppin wrote:
recognisable expression involving GHC.Prim.+##. (Anybody know what
the difference between GHC.Prim.Double# and GHC.Float.Double is?)
This in spite of the fact that the definition is actually
Double# is an unboxed (raw) double; Double is
| Ah well, I doubt I'm going to come up with any new ideas for how to make
| my code go faster, but it's mildly entertaining wading through over 200
| KB of textual output trying to guess what it means.
Ha ha. You did say that you wanted to know what GHC *really* does :-)
Seriously, there is
Hello Haskellers,
I have a problem where GHC will hang after compiling a file. The problem
seems to occur with my computer, but not with everyone else's. I hope that
someone my be able to diagnose my problem.
My computer is an Acer Aspire 5670, which runs on an Intel Core Duo T2300
and runs
Simon Peyton-Jones wrote:
| Ah well, I doubt I'm going to come up with any new ideas for how to make
| my code go faster, but it's mildly entertaining wading through over 200
| KB of textual output trying to guess what it means.
Ha ha. You did say that you wanted to know what GHC *really* does
| I wonder... is there a high-level document anywhere which explains what
| GHC actually does with your code when you compile it?
A lot, actually:
http://hackage.haskell.org/trac/ghc/wiki/Commentary
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Hi
Do you mind tell what is mean by the symbol $ in this piece of code? Thanks
a lot.
mcompile :: Prog - State Int Code
mcompile (Assign n e) = return $ compileExpr e ++ [POP n]
mcompile (If e p1 p2) = do cur - fresh
pp1 - mcompile p1
hi
I am a newbee to haskell so please forgive me if the question is not
appropreate.
I am trying to get the idea of using Monad and have to understand the
following code.
Can you please tell me is how different Monad and Monad transformer is?
And what is mean by
newtype State s a = State {
Maverick,
Do you mind tell what is mean by the symbol $ in this piece of
code? Thanks
a lot.
It denotes function application:
infixr 1 $
($) :: (a - b) - a - b
f $ x = f x
Note how its precedence and associativity is the opposite of that of
'regular' function application. The
Maverick,
Can you please tell me is how different Monad and Monad transformer
is?
Perhaps this is of interest to you:
http://www.haskell.org/all_about_monads/html/
HTH,
Stefan
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Sorry, my mail client fooled me, too, so here it is again:
Andrew Coppin:
What I'm trying to say is, I would have expected, say,
resultant :: [Vector2] - Vector2
resultant = sum
to run faster than
resultant = sum
In the latter case, we have resultant :: (Num n) = [n] - n.
So... if I'm not actually using lazyness for anything, would it do
any harm to change Double to Double# in the Haskell source code? Or
is there some reason why this would be undesirable? (The source is
carefully constructed
Well, you'd need -fglasgow-exts for it to even compile. Other than
Simon Peyton-Jones wrote:
| I wonder... is there a high-level document anywhere which explains what
| GHC actually does with your code when you compile it?
A lot, actually:
http://hackage.haskell.org/trac/ghc/wiki/Commentary
Ooo... candy!
(By the way... I'm loving the whole concept of
---
Haskell Weekly News
http://sequence.complete.org/hwn/20070507
Issue 62 - May 07, 2007
---
Chaos. Andrew Coppin [29]announced chaos, a fun
Thanks a lot for your help
I got the idea of this symbol now.
It will be great if you can help me this time as well, this time is the
symbol @
Here is the code that i got
evalExpr :: Expr - Mem - (Bool,Expr)
evalExpr (Val x) _= (True,Val x)
evalExpr
(False,Var n) else (True,Val (envLookup n env))
evalExpr c@(App op e1 e2) e = let (b1,v1) = (evalExpr e1 e)
(b2,v2) =(evalExpr e2 e)
in if b1 b2 then (True,Val (eval c e)) else (False,App op v1 v2)
Allows you to refer
On Sun, 6 May 2007, Andrew Coppin wrote:
Greetings.
Haskell has arbitrary precision integers, in the form of the Integer
type. Is there a type somewhere that implements arbitrary precision
fractional values?
Whatever you want:
On 07/05/07, Andrew Coppin [EMAIL PROTECTED] wrote:
(Anybody know what the difference between GHC.Prim.Double#
and GHC.Float.Double is?)
It's the difference between unboxed and boxed types. A boxed type's
representation is in fact a pointer to the unboxed type (I think), so
that a Double would
On Mon, 2007-05-07 at 21:50 +0100, David House wrote:
On 07/05/07, Andrew Coppin [EMAIL PROTECTED] wrote:
(Anybody know what the difference between GHC.Prim.Double#
and GHC.Float.Double is?)
It's the difference between unboxed and boxed types. A boxed type's
representation is in fact a
Folks,
Are you using UU.PPrint [1]? Can you tell me how to print stuff like
this?
{
blah
blah
}
I tried the following which sort of works but doesn't return the
closing brace to the indentation level of the first one.
braces x = PP.braces $ linebreak indent 4 x
On 07/05/07, David House [EMAIL PROTECTED] wrote:
represented by a null pointer. So such luck with unboxed types. So
working with unboxed types is quicker and consumes less memory, but
don't use them in any kind of high level because the lack of a _|_
will bite you sooner or later.
I hesitate
i've run ghc 6.6, and other open source software, on a core duo
thinkpad without any problems. building bisect.hs works fine as well.
I am using the winxp professional sp 2.
On 5/7/07, Josiah Manson [EMAIL PROTECTED] wrote:
Hello Haskellers,
I have a problem where GHC will hang after
Looking at the libraries documentation, it seems like parsing a string into
a time and date should be as simple as:
import Data.Time.Format (parseTime)
myDate = parseTime ...
where ... is some string. But these functions don't seem to exist! I can't
find many references to them in the wild,
On Mon, May 07, 2007 at 10:38:19PM +0100, Joel Reymont wrote:
Folks,
Are you using UU.PPrint [1]? Can you tell me how to print stuff like
this?
{
blah
blah
}
I tried the following which sort of works but doesn't return the
closing brace to the indentation level of the
http://www.haskell.org/ghc/dist/6.6.1/ghc-6.6.1-i386-windows-test1.exe
Might be worth trying that to see if there's still a problem.
There is still a problem when I use the version you linked to. At first I
was hopeful, because the first time I tried compiling bisect.hs it worked.
All
When the intermediate files are removed, GHC still hangs. In fact, the
intermediate files do not seem to be corrupt in any way, as the only way to
get a working executable is to run GHC more than once. First to produce the
intermediate files, then to link them into an executable.
On 5/7/07, Cale
On 5/7/07, Josiah Manson [EMAIL PROTECTED] wrote:
When the intermediate files are removed, GHC still hangs. In fact, the
intermediate files do not seem to be corrupt in any way, as the only way to
get a working executable is to run GHC more than once. First to produce the
intermediate files,
In Haskell, is it possible to declare a type constructor with a variable
number of type variables e.g.
data Tuple *
allowing the following declarations:
t: Tuple
u: Tuple Bool
v: Tuple Bool Int
w: Tuple Bool Int Char
Although the data constructor such as the `Tuple' is not
I have generated log files with both filemon and procmon. The procmon output
may be useful. ghc.exe launches gcc.exe which launches as.exe which does
various things, but the last thing as.exe does before all goes silent is
this line:
1655510:24:30.0592945 PMas.exe4364RegOpenKey
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