Thomas,
let x = ... in ...
is only equal
do x - ...; ...
in the Identity monad. Also, why would do be more primitive than
let. That way you would have to use monads everywhere. Also,
let is treated specially by the type checker (IIRC) and there are
many, many other reasons not
Thomas, Stefan,
Thanks for a most edifying exchange! i will reflect on this.
Best wishes,
--greg
On 6/28/07, Stefan Holdermans [EMAIL PROTECTED] wrote:
Thomas,
let x = ... in ...
is only equal
do x - ...; ...
in the Identity monad. Also, why would do be more primitive than
clawsie:
i have written a small haskell program to solve a problem many users
of freebsd may have - knowing what ports have been updated after a
daily/weekly etc cvsup. this is a trivial bit of coding hardly worth
attention, but if it might be of use to you, you can find it here:
Dave Bayer wrote:
[...] In the Haskell do expression, every line is equally special,
and type information is used to combine the lines, inserting implied
combinators.[...]
Desugaring do-notation is a syntactic transformation, requiring no type
information. (In practice, the parts may be
What is the advantage of using Haskell in this case?
bryan is correct! i hesitated to even bother the cafe list with this,
considering it is so trivial, but i just wanted to learn a bit more
about haskell's file and directory functionality, and this bit of code
may be something others can look
On Fri, 29 Jun 2007, Dave Bayer wrote:
One is immediately led back to the same idea as Haskell do expressions:
Two pieces of program, juxtaposed next to each other, silently
multiply to combine into a larger program, with type rules guiding the
multiplication process.
They don't,
I wrote a combination reader/writer monad (a la the RWS monad in the
mtl) and I find myself wanting to use multiple instances of it in the
same stack of transformers. The functional dependencies prevent this
from working out. The class is called MonadRW and the transformer is
called RWT.
I find
On 29 jun 2007, at 16.26, Dave Bayer wrote:
That way you would have to use monads everywhere.
As you already hinted at in a later message, this has to do with
let-bindings being potentially polymorphic and monadic bindings
being necessarily monomorphic:
Are there papers that prove this
A while back I saw a toy tcl interpreter in 550 lines of C called
'picol'. I was looking for a simple language to implement in haskell,
so I made my own toy tcl interpreter. It was surprisingly easy to
make, thanks to the magic of Haskell and Bytestrings. :) It handles a
few things incorrectly,
Hello Nicolas,
Friday, June 29, 2007, 9:07:38 PM, you wrote:
I'm rather unfamiliar with Template Haskell, but it sounds like it
might fit the bill. Although, if I recall correctly, instances and
type declarations splicing are yet to be implemented in GHC?
instances - definitely not. i've
I vaguely remember to have read that HGL is (currently) not supported on
Windows, but I can't find this information any more.
Is this correct? It seems not to be included in GHC 6.6
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Andrew Coppin wrote,
If this was Java, you would write all these compression and
decompression stages as stream wrappers. So you wrap the raw input
stream with an RLE decoder, have the function read the Huffman table,
and then take off the RLE decoder and process the rest of the stream.
Andrew Coppin [EMAIL PROTECTED] writes:
(snip)
Woah... Let me sit down and grok that for an hour or two. o_o
The Haskell learning curve - including the wonderful range of useful
generic stuff you can do with it - extends way higher than for many
other languages, I think, though you can write
Stefan O'Rear wrote:
On Fri, Jun 29, 2007 at 07:18:00PM +0100, Andrew Coppin wrote:
Well, let me show you the code - somebody will probably recognise this
stuff...
convert1 :: Expression - Expression
convert1 S = S
convert1 K = K
convert1 I = I
convert1 (Var v) = Var v
convert1 (x :@: y) =
On Fri, Jun 29, 2007 at 07:39:28PM +0100, Andrew Coppin wrote:
Now I have a problem. It's easy enough to pass the entire data stream
through an RLE decoder and feed that to the Huffman table deserialize
function, and it will give be back the table. But I now have *no clue*
where the table
Andrew Coppin writes:
I wonder what the layout for that is... something like this?
case foo of
patter1
| guard1 - ...
| guard2 - ...
pattern2
| guard3 - ...
| guard4 - ...
Something like that should work. If the patterns are more indented than
On Thu, Jun 21, 2007 at 05:39:12PM +0300, Bit Connor wrote:
now - getCurrentTime
2007-06-21 13:48:44.298699 UTC
formatTime defaultTimeLocale %s now
1182433724
formatTime defaultTimeLocale %Q now
%q also always gives me an empty string.
It seems to work OK for me with GHC 6.6.1 and
| By the way, using Integer for exponents really shouldn't be less
| efficient -
| but it seems it is.
|
| The code for (^) should be something like this:
|
| {-# INLINE ^ #-}
| n ^ m = case toInteger m of
| S# i - powerInt# n i
| J# a p - powerGmp n a p
I've done something
On Friday 29 June 2007, Andrew Coppin wrote:
...and again today I found myself trying to do something that would be
very easy in an imperative language, but I cannot think of a single good
way of doing it in Haskell. Hopfully somebody can give me some hints.
snip long and helpful explanation
Unfortunately your memory serves you well -- see:
http://hackage.haskell.org/trac/ghc/ticket/742
-Paul
peterv wrote:
I vaguely remember to have read that HGL is
(currently) not
supported on Windows, but I cant find this information any more.
Is this correct? It seems
On Friday 29 June 2007, Jon Cast wrote:
Here's my solution (drawn from a library I'll be posting Real Soon Now):
snip solution
I forgot to point out that this is 75-90% drawn from a library called
Fudgets[1], which is probably the most extended practical meditation to date
on programming with
David Roundy wrote:
On Fri, Jun 29, 2007 at 07:39:28PM +0100, Andrew Coppin wrote:
Now I have a problem. It's easy enough to pass the entire data stream
through an RLE decoder and feed that to the Huffman table deserialize
function, and it will give be back the table. But I now have *no
On Friday 29 June 2007, Andrew Coppin wrote:
Jon Cast wrote:
On Wednesday 27 June 2007, Andrew Coppin wrote:
Wow, wait a sec - case expressions are allowed to have guards too??
Yes. I guess I assumed you knew that, sorry.
The only syntactic (or semantic) difference between function
On Wed, Jun 27, 2007 at 09:42:29PM -0700, Justin Bailey wrote:
Any feedback, let me know. Thanks!
Thanks for looking at this, Justin! Looks fine to me.
Ian
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On Fri, Jun 29, 2007 at 07:26:21AM -0700, Dave Bayer wrote:
On Jun 28, 2007, at 9:49 PM, Stefan Holdermans wrote:
That way you would have to use monads everywhere.
As you already hinted at in a later message, this has to do with
let-bindings being potentially polymorphic and monadic
consalus:
A while back I saw a toy tcl interpreter in 550 lines of C called
'picol'. I was looking for a simple language to implement in haskell,
so I made my own toy tcl interpreter. It was surprisingly easy to
make, thanks to the magic of Haskell and Bytestrings. :) It handles a
few things
On Jun 29, 2007, at 10:07 AM, Nicolas Frisby wrote:
I wrote a combination reader/writer monad (a la the RWS monad in the
mtl) and I find myself wanting to use multiple instances of it in the
same stack of transformers. The functional dependencies prevent this
from working out.
I found myself
Date: Mon, 25 Jun 2007 20:19:50 -0400
To: Jens Fisseler [EMAIL PROTECTED]
From: Dean Herington [EMAIL PROTECTED]
Subject: Re: [Haskell-cafe] avoiding command window with wxHaskell on Windows?
Cc: haskell-cafe@haskell.org, [EMAIL PROTECTED]
At 10:10 PM +0200 6/23/07, Jens Fisseler wrote:
On Sat,
I have a very complex project that has to play nice with a lot of C code
written by other people.
My own code is half Haskell and half C. My build process is rather complex
since I generate about 5 different libraries, some of them export Haskell
routines. A supreme effort was made to try to
SevenThunders wrote:
perhaps what's contained in foo.hi that informs ghc what names to actually
link to.
I'm not so sure if this is correct or not. The truth is I have no .hi files
in the directory I try to link my test code, and yet it's somehow finding
them in the cabal created
First post. I'm a newbie, been using Haskell for about a week and love it.
Anyway, this is something I don't understand. Parsers are monadic. I can see
this if the parser is reading from an input stream but if there's just a block
of text can't you just have the parser call itself
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