clisper clisper at 163.com writes:
haskell is greate
but i don't know how to start.
Don't!
Learning Haskell will change your world! For worse! Really! Don't do that,
you still have time to go back! Or be damned like all of us here...
Referential transparency will suck up your soul.
Hi,
My program is eating too much memory:
copyfile source.txt dest.txt +RTS -sstderr
Reading file...
Reducing structure...
Writting file...
Done in 20.277s
1,499,778,352 bytes allocated in the heap
2,299,036,932 bytes copied during GC (scavenged)
1,522,112,856 bytes copied during GC (not
Stefan O'Rear stefanor at cox.net writes:
Note that heap profiling is even more a black art than time profiling;
you may need to do a lot of experimentation to find an enlightening
profile.
Black art indeed... I did -hc, looked at the postscript generated from every
angle I could and it
Ketil Malde ketil+haskell at ii.uib.no writes:
Gracjan Polak gracjanpolak at gmail.com writes:
let entries = IntMap.fromList (map (\(a,b,c) - (a,c)) (concat p))
Gut reaction: Map is lazy in its values (but probably not the key,
which are checked for order), so you should force
Ketil Malde ketil+haskell at ii.uib.no writes:
Then you get the memory behavior you ask for. Unevaluated strings are
extremely expensive, something like 12 bytes per char on 32 bit, twice
that on 64 bits, and then you need GC overhead, etc. ByteStrings are
much better, but you then
Don Stewart dons at galois.com writes:
ByteStrings have all the same operations as lists though, so you can
index, compare and take substrings, with the benefit that he underlying
string will be shared, not copied. And only use 1 byte per element.
Is there any parser built directly over
Gracjan Polak gracjanpolak at gmail.com writes:
Don Stewart dons at galois.com writes:
ByteStrings have all the same operations as lists though, so you can
index, compare and take substrings, with the benefit that he underlying
string will be shared, not copied. And only use 1 byte
I'm happy to announce a ReadP style parser for ByteStrings,
Text.ParserCombinators.ReadP.ByteString.
http://hackage.haskell.org/cgi-bin/hackage-scripts/package/bytestringreadp
Text.ParserCombinators.ReadP.ByteString is an adaptation of
Text.ParserCombinators.ReadP to work over Data.ByteString
I'd like to add a warning to this discussion.
You might be affected by this issue:
http://trac.haskell.org/network/ticket/11
TL;DR: It is kind of random if you bind to IPv4 or IPv6 or both. For example
Windows Vista likes to bind to IPv6 only.
Watch your ports and protocols!
--
Gracjan
Hi all,
Tried to use :break today, without success:
guestbook-session-bugghci -DMIN_VERSION_template_haskell(a,b,c)=1
-isrc Main -i../happstack/happstack-ixset/src
GHCi, version 6.12.1: http://www.haskell.org/ghc/ :? for help
...
...
[10 of 13] Compiling Happstack.Data.IxSet (
Recently I started to play with Happstack and I must say I'm amazed how good it
works for me! It has server, string templating, type safe html templating,
persistence (like a database, only more fun), email stuff.
To get a grasp at what goes under Happstack name here is a tutorial:
Alberto G. Corona agocorona at gmail.com writes:
Hope that this cold answer don't end this funny thread ;(
Those concerned with Haskellers to Haskellinas ration can always employ this
technique:
http://www.newton.dep.anl.gov/askasci/bio99/bio99128.htm
Any volunteers? :)
--
Gracjan
Antoine Latter aslatter at gmail.com writes:
Sending off to the maintainer of haxr, although it looks like it might
be in HaXml (from an outside guess).
Without some real example to look at it will be quite tough to proceed.
Alexander, can you send that stream of packets to me?
--
Gracjan
Alexander Kotelnikov sacha at myxomop.com writes:
On Wed, 21 Jul 2010 06:46:26 + (UTC)
GP == Gracjan Polak gracjanpolak at gmail.com wrote:
GP
GP Antoine Latter aslatter at gmail.com writes:
Sending off to the maintainer of haxr, although it looks like it might
be in HaXml (from
Hi all,
A question for hot summer day: Text.ParserCombinators.ReadP.ReadP is
an instance of Monad. Could it be an instance of MonadFix too?
I'm not that sharp in Haskell to write it myself, but it seems I could
make use of such a beast. :) Anybody willing to share?
This will also present the
is a MonadFix instance of P; which is definitely
doable with the current techniques. Anything further would actually make a
nice research paper...
-Levent. (I could provide references to above work if needed; all is
available on the net freely, anyhow.)
On 6/23/06, Gracjan Polak [EMAIL PROTECTED
Hi,
I wanted to setup really simple http server, found Network.CGI.Compat.pwrapper
and decided it suits my needs. Code:
module Main where
import Network.CGI
import Text.XHtml
import Network
doit vars = do
return (body (toHtml (show vars)))
main = withSocketsDo (pwrapper (PortNumber )
Bjorn Bringert bringert at cs.chalmers.se writes:
Another question is: how do I do equivalent functionality without
pwrapper?
You can roll you own web server if you want something very simple. If
you don't want to do that, there is a version of Simon Marlow's
Haskell Web Server
Bjorn Bringert bringert at cs.chalmers.se writes:
Is there a description what is a *CGI* protocol?
Here you go: http://hoohoo.ncsa.uiuc.edu/cgi/interface.html
I should be more clear: what kind of data does pwrapper expect? Somewhere in the
middle it needs two handles: one to write and
My strictness analyser in my brain hurts. Which one (foldl,foldl',foldr) is the
best way?
Prelude Data.Set Data.List let s = fromList [1,2,3,4,5]
Loading package array-0.1.0.0 ... linking ... done.
Loading package containers-0.1.0.0 ... linking ... done.
Prelude Data.Set Data.List foldl (.) id
Duncan Coutts duncan.coutts at worc.ox.ac.uk writes:
Data.List.foldr (Data.Set.delete) s [1,3,5]
or
Data.List.foldl' (flip Data.Set.delete) s [1,3,5]
There will be a day when I finally grasp foldr/foldl :)
which is O (n + m * log m) rather than O(m * log n) or if the elements
you're
Hello fellow haskellers,
While reading reddit in the morning today:
http://www.reddit.com/r/programming/comments/a26fe/dont/
I was shocked and surprised to see that Haskell lacks a very important
feature present in Perl. It appeared that Haskell cannot not do
monadic actions!
I decided to act
Deniz Dogan deniz.a.m.dogan at gmail.com writes:
Are you sure you want to license this as BSD?
Yes, BSD3 to be more exact.
Of course commercial options are available on case by case basis.
--
Gracjan
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Michael Hartl mikehartl at web.de writes:
BTW, what's the status of HaXR? Is it being actively developed?
Developed not. Maintained yes, by me. And you can argue that 'actively' part.
Please send patches against
darcs get http://code.haskell.org/haxr
--
Gracjan
Hi all,
I have base==3.* code that uses errorCalls and ioErrors to intercept either
ErrorCall or IOError that may arise in deeper code.
I'd like to convert this code to base==4.* new exceptions.
-- | Evaluate the argument and catch error call exceptions
errorToErr :: Monad m = a - Err m a
Dmitri Pissarenko wrote:
Hello!
I have two lists of Double with equal length and want to create a
third one,
in which each element is the sum of the corresponding element of the
first
list and the second list.
If list1 is [1, 2, 100] and list2 is [2, 3, 500], then the result of the
S. Alexander Jacobson wrote:
I am using GHC 6.2 on windows and am finding that when I open a file and
use hFileSize I get a different number than I get from reading in the
file and calculating the length. I assume this is not a bug, but I
don't know why its happening.
Isn't that because of
Hi all,
As I tried to convert some of my code to newer libraries comming with
GHC 6.4, I would like to share two things with you:
I noticed that there are two functions missing: deleteList and
insertList. The first one is easy with foldl:
deleteList list map = foldl (flip Data.Map.delete) map
Sebastian Sylvan wrote:
On Apr 3, 2005 9:38 AM, Gracjan Polak [EMAIL PROTECTED] wrote:
insertList asclist map = union map (Data.Map.fromList asclist)
How about:
insertList :: (Ord a) = Map a b - [(a, b)] - Map a b
insertList = foldr (uncurry insert)
Is there any reason why foldr is better than
Daniel Carrera wrote:
Hi all,
Thank you for all the information on my previous question. I learned a
lot, and good pointers to more info.
My next question is about speed. How fast would you consider Haskell?
(say, for computational work). How would you compare it to C, Python and
Ruby?
I
Hi,
Simple question: I need a function that matches string in another
string. Something like:
find (isSuffixOf needle) (inits haystack)
This one is beautiful, but not very practical. Could anybody point me to
some haskell library that does some searching, using KMP for example?
--
Gracjan
Ketil Malde wrote:
Gracjan Polak [EMAIL PROTECTED] writes:
find (isSuffixOf needle) (inits haystack)
Hmm...
While the result isn't exactly the same, I suspect
using isPrefixOf and tails would be more efficient.
I need the data before and including my needle. Like this:
( ... needle
Marcin 'Qrczak' Kowalczyk wrote:
Gracjan Polak [EMAIL PROTECTED] writes:
intern :: Ord a = a - a
intern x = unsafePerformIO $ internIO x
iorefset :: Ord a = IORef(Map.Map a a)
iorefset = unsafePerformIO $ do
newIORef $ Map.empty
It will not work because you can't put values
Scott Turner wrote:
On 2005 June 02 Thursday 04:38, Gracjan Polak wrote:
iorefset :: Ord a = IORef(Map.Map a a)
iorefset = unsafePerformIO $ do
newIORef $ Map.empty
I could have as many dictionaries as there are types. The problem is I
get one dictionary for each object which defeats
Duncan Coutts wrote:
On Fri, 2005-06-03 at 10:53 +0200, Gracjan Polak wrote:
As intern behaves like id and does not have any side effects, I thought
its interface should be purely functional. But I do not see any way to
do it :( I'll end up with a monad, probably.
In related question: does
Cédric Paternotte wrote:
Hi. This is my first message here so Hello to everyone.
I'm just starting to learn Haskell and I really think it's a cool
language.
Me too :)
I know OO and inheritance is not really the point of Haskell and that
other mechanisms are provided to somewhat achieve
Hi,
Sorry for stupid question, but...
Some time ago I read a beautiful paper about variables that had their
dependencies automatically tracked and could trigger recalculation when
changed. Prototype was implemented in OCaml, then reimplemented in
Haskell (using monads). I would like to
Hello,
My space problems continued...
I have foldl that produces list, some combining function and quite large
source list:
let xyz = foldl f state myBigList
This setting should lazyli consume myBigList when next elements of xyz
are demanded. Except that it seems that myBigList is held by
Cédric Paternotte wrote:
Hi Gracjan,
This is smart. So I understand the point of this part is to forward
the function call to the parent (through get_super). All you have to
do is to define these forwards in each inheriting data.
Yes. I think this is the whole point of inheritance :)
Does
Ralf Lammel wrote:
Cédric Paternotte wrote:
...
5. With this :
http://www.cs.utexas.edu/ftp/pub/techreports/tr01-60/tr01-60.pdf
Gracjan Polak wrote:
I've been thinking about slight generalization of this lately. Here are
my semi-backed thoughts as of now.
I should have mentioned
http
Hi,
I the paper of Magnu Carlsson I noticed small, interesting class:
class Monad m = Ref m r | m - r where
newRef :: a - m (r a)
readRef :: r a - m a
writeRef :: r a - a - m ()
He defined it locally, but it seems to be very useful generalization of
IORef and STRef. Is there
Bernard Pope wrote:
A more practical solution is to force the compiler to generate more
strict code.
I tried to put strictness annotation in every place I could think of.
Without result :(
You might also find GHood useful:
Bulat Ziganshin wrote:
Hello Gracjan,
Tuesday, June 07, 2005, 2:25:50 PM, you wrote:
class Monad m = Ref m r | m - r where
GP newRef :: a - m (r a)
GP readRef :: r a - m a
GP writeRef :: r a - a - m ()
may be the following will be even more interesting:
I like it very much!
Tomasz Zielonka wrote:
On Tue, Jun 07, 2005 at 12:25:50PM +0200, Gracjan Polak wrote:
Another question: priority queue. In libraries bundled with ghc we have
Data.Queue, but I couldn't find PriorityQueue. Is there somewhere an
implementation that everybody uses, but is not in the library
Bjorn Bringert wrote:
memory. Here is something I wrote, but it doesn't work :(
I must have been doing something really wrong that day, because today it
works smoothly... :)
The code below seems to work for strings, and should be generalizable to
any type for which you have a hash
Udo Stenzel wrote:
Gracjan Polak wrote:
iorefset :: Ord a = IORef(Map.Map a a)
iorefset = unsafePerformIO $ do
newIORef $ Map.empty
I could have as many dictionaries as there are types. The problem is I
get one dictionary for each object which defeats the idea.
I believe the (Ord
David Menendez wrote:
[many things deleted]...
I think the best way to look at MonadRef is as a generalization of
MonadState.
This could be a way to transliterate (not translate, transliterate) many
imperative programs to Haskell. And as such this could be a starting
point for many
Hi,
My space problems continued... :)
I have some ForeignPtr's, with finalizers (finalizerFree only). And I
have lazyly produced list of those (yes, there is some unsafePerformIO
magic behind, but I think I got this right). The problem is I get
out-of-memory condition because elements get
Bernard Pope wrote:
Perhaps you could post the definition of the state type? Or even better,
a small example of code that runs badly.
I still don't know where old code had problems, but after rewriting
everything it seems to run smoothly now :) Thanks for all ideas, btw.
I invented
Simon Marlow wrote:
I presume you're running GHC. There's no way to increase the priority
of a thread - GHC's scheduler doesn't have a concept of priorities.
Yes, I forgot to state it explicitly.
I would look into whether you can use mallocForeignPtr: this is much
faster than using
Sebastian Sylvan wrote:
On 6/13/05, Simon Marlow [EMAIL PROTECTED] wrote:
I presume you're running GHC. There's no way to increase the priority
of a thread - GHC's scheduler doesn't have a concept of priorities.
Just out of curiousity, what scheme does GHC use for scheduling threads?
Simon Marlow wrote:
On 13 June 2005 11:30, Gracjan Polak wrote:
My space problems continued... :)
Follow up :)
I have some ForeignPtr's, with finalizers (finalizerFree only). And I
have lazyly produced list of those (yes, there is some unsafePerformIO
magic behind, but I think I got
Bulat Ziganshin wrote:
Hello Gracjan,
Tuesday, June 14, 2005, 1:29:09 PM, you wrote:
GP Documentation says:
GP -Msize
GP [Default: unlimited] Set the maximum heap size to size bytes. The
GP heap normally grows and shrinks according to the memory requirements of
GP the program...
GP
Hi all,
A simple question for advanced Haskellers, but I still have some
problems bending my mind over it.
Example: I have some function, that can return multiple results.
Currently I need only the first one, but in the spirit of NotJustMaybe,
I try to be as general as possible.
If I
Duncan Coutts wrote:
Most toolkits with a main loop system allow you to setup timers. In the
Gtk2Hs bindings we can use this trick:
-- 50ms timeout, so GHC will get a chance to scheule about 20 times a second
-- which gives reasonable latency without the polling generating too much
-- cpu
Hi,
Probably very simple question about template haskell: How do I make a
type for an argument to splice? Example:
data MyData = MyData1 | MyData2
mysplice mytype =
[| litE $ stringL $ show mytype |]
main = do
putStrLn $(mysplice MyData)
The above is not accepted, error:
Compiling
Tomasz Zielonka wrote:
On Mon, Sep 12, 2005 at 12:08:14PM +0200, Gracjan Polak wrote:
Probably very simple question about template haskell: How do I make a
type for an argument to splice? Example:
data MyData = MyData1 | MyData2
mysplice mytype =
[| litE $ stringL $ show mytype |]
main
Simon Peyton-Jones wrote:
| putStrLn $(mysplice ''MyData)
|
|
| Thanks for responses. Is there any up-to-date documentation avaliable?
Template Haskell is, alas, poorly documented. I would really welcome
someone to volunteer to help write better documentation. Meanwhile, as
the user
Hi all,
The Q Monad in template haskell has fail method. As I understand it, it
throws some kind of exception. How do I catch this exception?
Some code I'm trying to create:
infoToCode :: Info - Q Exp
infoToCode (ClassI dec) = -- ClassI Dec
fail ClassI not supported -- this will be
Simon Peyton-Jones wrote:
design note http://research.microsoft.com/~simonpj/tmp/notes2.ps
In the above paper there is something about 'giveUp'. Seems to quite
useful, but there is no such thing in ghc 6.4.
Where did my giveUp go? And why?
--
Gracjan
failing test cases?
--
Gracjan
Simon
| -Original Message-
| From: Gracjan Polak [mailto:[EMAIL PROTECTED]
| Sent: 20 September 2005 10:43
| To: Simon Peyton-Jones
| Cc: haskell-cafe@haskell.org
| Subject: Re: [Haskell-cafe] Template Haskell and Types
|
| Simon Peyton-Jones wrote
Hi,
Could somebody try to compile these two files *TWICE*? GHC dumps core at
me. I don't know if it is something about me, or something more general
:) I'd like to know a bit more, before I bother anybody from devel team.
Log:
$ ghc --make THTest1.hs
Chasing modules from: THTest1.hs
2005/11/19, Benjamin Franksen
[You should read some of his papers, for instance the most unreliable
techique in the world to compute pi. I was ROTFL when I saw the title
and reading it was an eye-opener and fun too.]
Care to post a link? Seems interesting, but unknown to google :)
--
Hi all,A bit strange behaviour with hPutStrLn. Consider following program:main = do handle - openFile output.txt WriteMode hPutStrLn handle (unlines contLines2) -- hFlush houtput
where contLines2 = flip map [1..2000] $ \x - show x ++ been there done thatOutputs file which ends with following
Thanks for the answers. I can go with hFlush or hClose, no problem here. Anyway this is a bit surprising that default stdout behaves different than file opened with default options. -- Gracjan
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Hi all,Is there any library to make Haskell call Microsoft COM functions using Dispatch? E.g I don't need the full COM binary functionality, scripting is enough. Google didn't seem to find anything interesting... beside rolling my own using FFI :)
Thanks in advance!-- Gracjan
2006/1/30, Paul Moore [EMAIL PROTECTED]:
On 1/30/06, Gracjan Polak [EMAIL PROTECTED] wrote: Is there any library to make Haskell call Microsoft COM functions using Dispatch? E.g I don't need the full COM binary functionality, scripting is
enough. Google didn't seem to find anything interesting
Bulat Ziganshin bulat.ziganshin at gmail.com writes:
Hello Hemanth,
Tuesday, August 17, 2010, 2:05:44 PM, you wrote:
btw, i've written unfinished hslua tutorial:
http://haskell.org/haskellwiki/HsLua
And in related news embedded Lua interpreter recently got upgraded
to version 5.1.4.
Change this:
succ - Lua.loadfile l /Haskell2Lua.lua
into
succ - Lua.loadfile l Haskell2Lua.lua
Note that 0 at the beginning says there was an error loading a script.
I should make it an exception I guess...
--
Gracjan
___
Haskell-Cafe mailing
aditya siram aditya.siram at gmail.com writes:
I was fooled :). Some indication of that on the page would be very
helpful.-deech
Bulat was dreaming about better Lua support, but since the thing fulfilled
my purpose, Bulat's dreams never got implemented.
Aditya, I'm eager to accept patches,
michael rice nowgate at yahoo.com writes:
I've been digging into this stuff for months and it's still tripping me up.
For exploration use GHCi. It can tell you the type of thing you have written. It
has command to tell you type of thing, the :t. See here:
Prelude let double x = Just (x + x)
Hi all,
In DEFUN 2009: Multicore Programming in Haskell Now!
(http://donsbot.wordpress.com/2009/09/05/defun-2009-multicore-programming-in-haskell-now/),
slide 30 I see:
Don't “accidentally parallelize”:
– f `par` f + e
and that the correct way of achieving parallelism is:
– f `par` e `pseq` f
Thanks for great response!
Brent Yorgey byorgey at seas.upenn.edu writes:
x `pseq` y guarantees to evaluate x before y. There is no such
guarantee with x `seq` y; the only guarantee with `seq` is that x
`seq` y will be _|_ if x is.
I found an old thread here
Dan Doel dan.doel at gmail.com writes:
On Sunday 06 September 2009 2:18:31 am David Menendez wrote:
It turns out, pseq limits the effectiveness of strictness analysis,
because it forces the order of evaluation. John Meacham described this
pretty well last week in the Haskell' list
Hi all,
On the other day I noticed that we could optimize 'sequence' more.
I needed it for my monadic parser. Below is my small experiment.
Sequence from standard library needs 2.3s to finish (and additional
stack space), my version uses only 0.65s and default stack.
Is my version better or am
Antoine Latter aslatter at gmail.com writes:
The function runIdentity is found in Control.Monad.Identity in the
mtl package.
Thanks, I see it now! Laziness is not there!
But still... Identity is a bit special monad. What other monads need full
laziness in sequence? As far as I know IO is
Chaddaï Fouché chaddai.fouche at gmail.com writes:
2008/7/22 Luke Palmer lrpalmer at gmail.com:
A little formal reasoning reveals that sequence1 = sequence2 exactly
when (=) is strict in its left argument. There are four common
monads which are _not_: Identity, Reader, Writer, State (and
Philippa Cowderoy flippa at flippac.org writes:
Haskell already has one method of overloading: type classes. What you
propose is a seemingly innocent extension that I now doubt has
extremely far-reaching consequences into the language. Such a feature
should be properly researched
Marcin 'Qrczak' Kowalczyk wrote:
fileRead :: File - FileOffset - Integer - Buffer - IO ()
This is unimplementable safely if the descriptor is read concurrently
by different processes. The current position is shared.
UNIX98 defines function:
extern ssize_t pread (int __fd, void *__buf,
Simon Marlow wrote:
There's a big lock on File. If you want to do truly concurrent reading,
you can make multiple FileInputStreams, each of which has its own file
descriptor (the Unix implementation uses dup(2)).
Original and descriptor returned by dup or dup2 share file pointer.
--
Gracjan
Hi,
I want to implement linear list shuffle in Haskell
(http://c2.com/cgi/wiki?LinearShuffle) and I invented code:
shuffle :: [a] - IO [a]
shuffle [] = return []
shuffle x = do
r - randomRIO (0::Int,length x - 1)
s - shuffle (take r x ++ drop (r+1) x)
return ((x!!r) : s)
This
Henning Thielemann wrote:
Is it a good idea to use IO monad for this plain computation?
It is needed as random number supply.
--
Gracjan
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John Meacham wrote:
Oleg wrote a great article on implementing the perfect shuffle. with
some sample code.
http://okmij.org/ftp/Haskell/misc.html#perfect-shuffle
Thats the kind of answer I was hoping to get :) Thanks.
shuffle could be useful in standard library. At least Python has it. I
Hi,
I stumbled at some interaction of Control.Monad.State.Strict, mdo and let I do
not understand. The following program:
{-# OPTIONS_GHC -fglasgow-exts #-}
module Main where
import Control.Monad.State.Strict
thenumber :: Float
thenumber = flip execState 1.3 $ mdo
c - donothing []
Hi all,
I'm pleased to announce the first public release of Scripting.Lua.
The package hslua-0.1 contains Haskell FFI bindings for a Lua interpreter
along with some Haskell utility functions simplifying Haskell to Lua and
Lua to Haskell calls. Full Lua interpreter is included in the package.
Donald Bruce Stewart dons at cse.unsw.edu.au writes:
Great work! would you like to upload it to hackage.haskell.org too, so
it will be archived for the ages?
I surely will, but I'd like to wait a moment and first see what people say :)
--
Gracjan\
Andrea Rossato mailing_list at istitutocolli.org writes:
I quote: this is a really nice news. I'll be trying to use it in
project of mine very soon (I'm developing a sort of Ion3 like status
bar, which is scriptable through Lua).
Exactly such a scenario I had in mind. Calling Lua from Haskell
Ketil Malde ketil at malde.org writes:
On Thu, Jan 15, 2009 at 07:46:02PM +, Andrew Coppin wrote:
If we *must* insist on using the most obscure possible name for
everything,
I don't think anybody even suggests using obscure names. Some people
insist on precise names.
Same here:
Vista, GHC 6.8.3
Tested a bit changed scenario: instead of 20 separate compilations it is
worthwhile to run single, longer build, e.g. ghc --make of same package.
Seems like GHCi does not run garbage collection when machine is busy. And then
it accumulates memory. This renders Vista
Alexander Danilov alexander.a.danilov at gmail.com writes:
03.03.2011 16:05, Hauschild, Klaus (EXT) пишет:
Hi Haskellers,
whats your Haskell IDE of choise? Currently I use leksah. Is the
EclipseFP Plugin for Eclipse a real alternative?
Thanks
Klaus
Emacs, look at haskell wiki
Ivan Lazar Miljenovic ivan.miljenovic at gmail.com writes:
Sounds similar to what haskell-indent does, except that it uses 2
spaces rather than 4, backspace does the chars less, and TAB also has
a version (albeit not as nice as the one in haskell-indentation) of
the tab-cycle.
I rejected
Hi all,
I have a project with a .cabal file listing package dependencies using
the usual version constraints ==X.Y.* Z.W or =K.J syntax.
Standard route cabal configure; cabal build works correctly as it is able
to select working set of package versions.
I have also a .ghci file. When I run GHCi
Henning Thielemann schlepptop at henning-thielemann.de writes:
You can manually select packages for GHCi with '-package' option.
However I do not know a way to automatically syncronise this with the
dependencies from the Cabal file.
I kind of expected 'cabal-dev ghci' to do this for me.
Ketil Malde ketil at malde.org writes:
In Haskell, I often need to add stubs of undefined in order to do
this. I don't mind, since it is often very useful to say *something*
about the particular piece - e.g. I add the type signature, establishing
the shape of the missing piece without
Hi all,
A why question: Why:
Control.Monad.Error Prelude runErrorT (fail msg) :: IO (Either String Int)
Left msg
but
Control.Monad.Error Prelude (fail msg) :: (Either String Int)
*** Exception: msg
?
--
Gracjan
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Thanks Daniel, Yves and Edward for explanation. Two things come to my mind now.
1. It should be unified. Why? Because conceptually:
runIdentity (runErrorT (fail msg)) :: Either String Int
Left msg
and
fail msg :: Either String Int
*** Exception: msg
Should be the same as Identity monad
Daniel Fischer daniel.is.fischer at googlemail.com writes:
On Monday 16 May 2011 23:41:44, Gracjan Polak wrote:
Thanks Daniel, Yves and Edward for explanation. Two things come to my
mind now.
1. It should be unified.
The (Either e) Monad instance was recently changed after people
Hi all,
It seems I'm not allowed to open same file both for writing and for reading:
Prelude System.IO f_out - openFile mylog.log AppendMode
Prelude System.IO f_in - openFile mylog.log ReadMode
*** Exception: mylog.log: openFile: resource busy (file is locked)
Usage scenario:
I use hslogger
Max Bolingbroke batterseapower at hotmail.com writes:
This behaviour is part of the Haskell 98 specification (section
21.2.3, http://www.haskell.org/onlinereport/io.html):
Thanks for the explanation. Such sharing behavior should be mentioned in
documentation:
Max Bolingbroke batterseapower at hotmail.com writes:
http://hackage.haskell.org/packages/archive/unix/2.4.2.0/doc/html/System-Posix-IO.html.
Thanks for the link. I tried to use it:
Prelude System.Posix.IO fd1 - openFd xxx.tmp WriteOnly (Just 0666)
defaultFileFlags
Loading package unix-2.4.0.2
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