[Haskell] ANNOUNCE: htags-1.0
http://hackage.haskell.org/cgi-bin/hackage-scripts/package/htags htags is a tag file generator to enable extra functionality in editors like vim. It expands upon hasktags by using a full Haskell 98 parser and options for recursion. -- David Sankel Sankel Software www.sankelsoftware.com 585 617 4748 (Office) 585 309 2016 (Mobile) ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
[Haskell] ANNOUNCE: rsa-haskell 2.0.1
RSA-Haskell is a collection of command-line cryptography tools and a cryptography library written in Haskell. It is intended to be useful to anyone who wants to secure files or communications or who wants to incorporate cryptography in their Haskell application. Download and documentation are available at http://www.netsuperbrain.com/rsa-haskell.html In this 2.0.1 release I've added a bunch of documentation and incorporated an archive with windows binaries for the command line tools. Please let me know if you have any questions or comments. Enjoy! David -- David Sankel Sankel Software www.sankelsoftware.com ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
Re: [Haskell] Re: putStr is not evaluated in the correct order
On 9/5/06, Bruno Martínez <[EMAIL PROTECTED]> wrote: C++ avoids this problem 'tieing' cin and cout. Why can't haskell do thesame?I was thinking the same thing. I'm imagining a situation where processes are communicating to each other using pipes, but cannot think of a concrete case. Do you know if C++ has any way to disable tying std::cin and std::cout? David ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
Re: [Haskell] Read Instances for Data.Map and Data.Set
On 10/19/05, Georg Martius <[EMAIL PROTECTED]> wrote: > I was really annoyed by the fact that for Data.Map and Data.Set are no Read > instances declared, but Show instances are! I believe there should be some > kind of unwritten rule that in the standart lib the Show and Read instances > come pairwise and are fully compatible. If there was this unwritten rule, should there not be other rules designed to ensure that reads and shows with interacting types are compatible? For example, I could imagine a type that would read and show on it's own, but a map of these objects wouldn't read and show correctly. I'm not suggesting this, but a possible solution would be to use parenthesis around every type and disallow a type to show to unmatched internal parenthesis. Regards, David ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
Re: [Haskell] Should inet_ntoa Be Pure?
Below is the relevant source code.
David
foreign import ccall unsafe "my_inet_ntoa"
c_inet_ntoa :: HostAddress -> IO (Ptr CChar)
foreign import CALLCONV unsafe "inet_addr"
c_inet_addr :: Ptr CChar -> IO HostAddress
-- -
-- Internet address manipulation routines:
inet_addr :: String -> IO HostAddress
inet_addr ipstr = do
withCString ipstr $ \str -> do
had <- c_inet_addr str
if had == -1
then ioError (userError ("inet_addr: Malformed address: " ++ ipstr))
else return had -- network byte order
inet_ntoa :: HostAddress -> IO String
inet_ntoa haddr = do
pstr <- c_inet_ntoa haddr
peekCString pstr
On 5/7/05, Dominic Steinitz <[EMAIL PROTECTED]> wrote:
> Does anyone know why these are in the IO monad? Aren't they pure functions
> converting between dotted-decimal strings and a 32-bit network byte ordered
> binary value?
>
> Dominic.
>
> http://www.haskell.org/ghc/docs/latest/html/libraries/network/Network.Socket.html#v%3Ainet_addr
> http://www.haskell.org/ghc/docs/latest/html/libraries/network/Network.Socket.html#v%3Ainet_ntoa
>
> ___
> Haskell mailing list
> Haskell@haskell.org
> http://www.haskell.org/mailman/listinfo/haskell
>
___
Haskell mailing list
Haskell@haskell.org
http://www.haskell.org/mailman/listinfo/haskell
Re: [Haskell] Re: 2-D Plots, graphical representation of massive data
A bit off topic, but a haskell charting/graphic library designer would be wise to check out the highly successful python equivelant, pychart. It seems as though a library equivelant in features to pychart is exactly what the original poster is looking for. David ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
[Haskell] Lists as Arrows
Hello, Forgive me, I have but a fuzzy idea of what Arrows are. I was thinking it might be possible to make lists arrows instead of monads. This would allow (++) to be one of those special arrow computations. It would have some quite nice properties. For example (++ [a]) could be a O(1) operation instead of a O(n). Also, the trivial implementation of a queue would be O(1) for push and pop operations instead of the more complicated amortized O(1) implementation. Am I missing the point or is what I said above a possibility? David J. Sankel ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: [Haskell] main::[String]->IO() ?
--- Steffen Mazanek <[EMAIL PROTECTED]> wrote: > I think this would simplify everyday-programming a lot. Or are there > any severe theoretical (semantical) problems (main is running in the IO > monad either way)? The type signature of main currently is: main :: IO() and the new type signature would be main :: [String] -> IO() Since type signature declarations for functions are generally considered good practice, those who use "<- getArgs" would actually need to type two extra characters. And those who do not use getArgs typically (which may or may not be the case in general), would type an extra 14 characters. One might also consider getProgName and getEnv to be plausible arguments to main as they are for some variants of c. However, in this case we are getting quite excessive with main's arguments. Aside from the two points made above, the current, no-argument version of main would support new programming models elegantly. Future systems development may lead to better system-program communication. GUI's, for instance, might have a special configuration line of communication for window placement which could be vastly superior to parsing a list of strings. Although there aren't any theoretical problems with main having an argument, I think that current practicioners would find it more efficient the way it is now. David J. Sankel ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: [Haskell] Implicit parameters redux
Ben, Could you explain in an extremely dumbed-down way what this is? It would be great if there were examples of 1) Some common, simple, and useful code in Haskell. 2) Same code using Implicit Parameters with a discussion of how it is better. Thanks, David J. Sankel ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: type classes, superclass of different kind
--- Robert Will <[EMAIL PROTECTED]> wrote:
-- > Here
-- > is a quesion for the
-- > most creative of thinkers: which is the design
(in
-- > proper Haskell or a
-- > wide-spread extension) possibly include much
-- > intermediate type classes and
-- > other stuff, that comes nearest to my desire?
Hello,
I've often wondered the same thing. I've found that
one can simulate several OO paradigms. Note that
these aren't particularly elegant or simple.
Using Data Constructors:
> data Shape = Rectangle {topLeft :: (Int, Int),
bottomRight :: (Int,Int) }
>| Circle {center :: (Int,Int), radius ::
Int }
This allows you have a list of shapes
> shapeList :: [Shape]
> shapeList = [ Rectangle (-3,3) (0,0), Circle (0,0) 3
]
When you want member functions, you need to specialize
the function for
all the constructors.
> height :: Shape -> Int
> height (Rectangle (a,b) (c,d)) = b - d
> height (Circle _ radius) = 2 * radius
Disadvantages:
1) When a new Shape is needed, one needs to edit the
original Shape source
file.
2) If a member function is not implemented for a shape
subclass, it will lead
to a run-time error (instead of compile-time).
Advantages:
1) Simple Syntax
2) Allows lists of Shapes
3) Haskell98
Example: GHC's exception types
http://www.haskell.org/ghc/docs/latest/html/base/Control.Exception.html
Using Classes
Classes can be used to force a type have specific
functions to act upon it.
>From our previous example:
> class Shape a where
> height :: a -> Int
>
> data Rectangle = Rectangle {topLeft :: (Int, Int),
bottomRight :: (Int,Int) }
> data Circle = Circle {center :: (Int,Int), radius ::
Int }
>
> instance Shape Circle where
> height (Circle _ radius) = 2 * radius
>
> instance Shape Rectangle where
> height (Rectangle (a,b) (c,d)) = b - d
In this case, something is a shape if it specifically
has the member
functions associated with Shapes (height in this
case).
Advantages
1) Simple Syntax
2) Haskell98
3) Allows a user to easily add Shapes without
modifying the original source.
4) If a member function is not implemented for a shape
subclass, it will lead
to a compile-time error.
Disadvantages:
1) Lists of Shapes not allowed
Example: Haskell 98's Num class.
http://www.haskell.org/ghc/
Classes with Instance holder.
There have been a few proposals of ways to get around
the List of Shapes
problem with classes. The Haskell98 ways looks like
this
> data ShapeInstance = ShapeInstance { ci_height ::
Int }
> toShapeInstance :: (Shape a) => a -> ShapeInstance
> toShapeInstance a = ShapeInstance { ci_height =
(height a) }
> instance Shape ShapeInstance where
> height (ShapeInstance ci_height) = ci_height
So when we want a list of shapes, we can do
> shapeList = [ toShapeInstance (Circle (3,3) 3),
> toShapeInstance (Rectangle (-3,3)
(0,0) ) ]
Of course this also has it's disadvantages. Everytime
a new memeber function is added, it must be noted in
the ShapeInstance declaration, the toShapeInstance
function, and the "instance Shape ShapeInstance"
declaration.
Using a haskell extention, we can get a little better.
Existentially quantified data constructors gives us
this:
> data ShapeInstance = forall a. Shape a =>
ShapeInstance a
>
> instance Shape ShapeInstance where
> height (ShapeInstance a) = height a
>
> shapeList = [ ShapeInstance (Circle (3,3) 3),
> ShapeInstance (Rectangle (-3,3) (0,0)
) ]
The benefits of this method are shorter code, and no
need to update the ShapeInstance declaration every
time a new member function is added.
Records extention
A different kind of inheritance can be implemented
with enhanced haskell
records. See
http://research.microsoft.com/~simonpj/Haskell/records.html
and
http://citeseer.nj.nec.com/gaster96polymorphic.html
for in depth explinations. I'm not sure if these have
been impemented or not, but it would work as follows.
The inheritance provided by the above extentions is
more of a data inheritance
than a functional inheritance. Lets say all shapes
must have a color parameter:
> type Shape = {color :: (Int,Int,Int)}
> type Circle = Shape + { center :: (Int,Int), radius
:: (Int) }
> type Rectangle = Shape + { topLeft :: (Int,Int),
bottomRight :: (Int, Int) }
So now we can reference this color for any shape by
calling .color.
> getColor :: (a <: Shape ) -> a -> (Int,Int,Int)
> getColor a = a.color
I'm not sure how the records extention could be used
with Classes with instance
holders to provide an even more plentiful OO
environment.
So I'll conclude this email with the observation that
Haskell supports some
OO constructs although not with the most elegance.
___
Haskell mailing list
[EMAIL PROTECTED]
http://www.haskell.org/mailman/listinfo/haskell
Doing weird things with types.
Hello All, I'm trying to create a generic function (*) using classes. I've been playing with ghc extensions but haven't found what I need yet. class HasTimes a b c where (*) :: a -> b -> c This doesn't work because it can't figure out what the return types are for a general expression a*(b*c). This kinda makes sense since someone could overload HasTimes Float Float Int and HasTimes Float Float Float. What about: class HasTimes a b where (*) :: a -> b -> c This would sort of imply that c is the only possible result of a (*) for types a and b. But I'm pretty sure this functionality hasn't been implemented. Why is this important? I'm trying to reduce ugliness of code using the following library: data Matrix = Matrix ((Float,Float),(Float,Float)) data HVec = HVec Float Float data VVec = VVec Float Float idMatrix = Matrix ((1.0,0.0),(0.0,1.0)) vhVecMult (VVec a b) (HVec c d) = Matrix ((a*c,a*d),(b*c,b*d)) matMult (Matrix ((a,b),(c,d))) (Matrix ((e,f),(g,h))) = Matrix (((a*e+b*g),(a*f+b*h)),((c*e+d*g),(c*f+d*h))) matVVecMult (Matrix ((c,d),(e,f))) (VVec a b) = VVec (a*c + b*d) (a*e + b*f) hVecMatMult (HVec a b) (Matrix ((c,d),(e,f))) = HVec (c*c+b*e) (a*d+b*f) vVecMinus (VVec a b) (VVec c d) = VVec (a-c) (b-d) vVecPlus (VVec a b) (VVec c d) = VVec (a+c) (b+d) matMinus (Matrix ((a,b),(c,d))) (Matrix ((e,f),(g,h))) = Matrix ((a-e,b-f),(c-g,d-h)) hvVecMult (HVec a b) (VVec c d) = a*c + b*d scalHVecMult :: Float -> HVec -> HVec scalHVecMult i (HVec a b ) = HVec (i*a) (i*b) Thanks, David J. Sankel ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
[ANNOUNCE] rsa-haskell 2.0.0
=== rsa-haskell 2.0.0 === RSA implementation in Haskell (rsa-haskell) contains the Simple and Strong Cryptography program set and Haskell libraries of several cryptographic standards. The libraries include haskell implementations of SHA1, EME-OAEP, EMSA-PSS, MGF, RSAES-OAEP, and RSA-PSS. These standards implement signature/verification, strong cryptography, and hashing. Also included in the library is a general number theory library. The Simple and Strong Cryptography program set contains simple programs for encrypting and decrypting files with public key cryptography as well as signature verification with public key cryptography. Changes from 1.2.0 to 2.0.0: Added implementation for several standard cryptographic protocols including SHA1, EME-OAEP, EMSA-PSS, MGF, RSAES-OAEP, and RSA-PSS. Refactored client code. Program names are now ssdecrypt, ssencrypt, sskeygen, sssign, and ssverify. Renamed client programs to the Simple and Strong Cryptography program set. see http://www.electronconsulting.com/rsa-haskell for details. David J. Sankel ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Haskell Networking Example
Hello All,
Here is an example of using haskell networking
operations for those interested. The implementation
is a simple echo server.
echoclient.hs:
module Main( main ) where
import Network
import IO
import Control.Concurrent
main :: IO ()
main = withSocketsDo $ --For windows compatibility
do
handle <- connectTo "localhost" (PortNumber 2048)
input <- getContents
sequence_ $ map ( \a -> do
hPutStr handle $ a ++ "\n"
hFlush handle ) $ lines input
hClose handle
echoserver.hs:
module Main( main ) where
import Network
import IO
import Control.Concurrent
main :: IO ()
main = withSocketsDo $ --For windows compatibility
do
theSocket <- listenOn (PortNumber 2048)
sequence_ $ repeat $ acceptConnectionAndFork
theSocket
where
acceptConnectionAndFork :: Socket -> IO ()
acceptConnectionAndFork theSocket = do
connection <- accept theSocket
let (handle, hostname, portnumber ) = connection
putStr ("("++ hostname ++ ":" ++ (show
portnumber) ++ "): Open\n" )
forkIO (echoServer connection)
return ()
echoServer :: (Handle, String, PortNumber) -> IO ()
echoServer (handle, hostname, portnumber ) = do
a <- hGetContents handle
putStr $ foldr (++) "" $ map (\a -> "(" ++ hostname
++ ":"
++ (show portnumber) ++ "): Msg " ++ (show
a) ++ "\n" ) $ lines a
putStr ("("++ hostname ++ ":" ++ (show portnumber)
++ "): Close\n" )
Makefile:
all: echoclient echoserver
echoclient: echoclient.hs
ghc -package network echoclient.hs -o
echoclient
echoserver: echoserver.hs
ghc -package network echoserver.hs -o
echoserver
clean:
rm *.o *.hi echoclient echoserver
___
Haskell mailing list
[EMAIL PROTECTED]
http://www.haskell.org/mailman/listinfo/haskell
Interesting Read
An interesting read: http://www.paulgraham.com/popular.html Any thoughts? David J. Sankel ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Proposal Proposal: haskell-gui addendum to haskell standard
Hello Everyone, I believe that haskell would have great benifit from a platform independant specification for a graphical user interface module or set of modules. I've been blessed with a lot of time on my hands so I'd be willing to organize this project if needed. Since there are several working haskell gui libraries out there, I would like this to be a collaboration project with those who are experienced in this area. Input and ideas from users would also be a part of the collaberation. The goal would be a specification much like the haskell report that could be freely implimented and a reference impementation. This is an informal proposal for a proposal and would like to get some feedback for the following ideas. (please reply to [EMAIL PROTECTED]) 1. Platform independance: The QT widget library is a stunning example of how platform independance is achievable without sacraficing speed. I am not suggesting that we build haskell-gui off of QT but might use major components of it as a model. Eventually, the library could have three backends; the Windows API, the X API (or gtk perhaps?), and the Mac API (the name illudes me at the moment). 2. Signals support: Having a signals mechanism is essential for large gui projects. 3. Dynamic widgets: All widgets should have dynamic size and should have the ability to be resized by the measurement of their contents or their parents. This could be done in a way similar to QT widgets. 4. GUI GUI builder: Widgets should be flexible enough to have the ability to be incorporated in a GUI GUI builder program, such as QT designer. The storage for a GUI builder might be direct Haskell code or some intermediate format. 5. OpenGL incorporation: haskell-gui should have some sort of OpenGL widget as OpenGL is the most standardized and multiplatform graphical library availible. Perhaps the hgl software could be incorporated in this aspect of haskell-gui. 6. Custom Widgets: It should be easy for one to create his or her own custom widgets from scratch using Haskell code or by some modification of the standard ones. Please give your feedback and suggestions for this project proposal proposal. If there is enough interest, I'll get this thing started. Kudos, David J. Sankel Head Consultant Electron Consulting (www.electronconsulting.com) ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: ANNOUNCE: Haskell Wiki resurrected
--- John Meacham <[EMAIL PROTECTED]> wrote: > On another note related to providing services to the > haskell comunity, > how about a public bugzilla server on > bugs.haskell.org? > (http://bugzilla.org) any haskell project which > wishes to use the public > bug server could be set up with an entry, it would > be nice to have a > central place to report bugs in the various haskell > systems as well. > This is not meant to replace whatever established > project have, but > rather provide a service to anyone with a haskell > project who wishes bug > reporting capability. I concur on this idea. This would be very useful. David J. Sankel ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Interpret haskell within haskell.
I was wondering if there is any project that aims to interpret haskell within haskell. Is it feasable that a program can import a user's .hs file that has something like: greeting :: String greeting = "Something" port :: Int port = 32 + 33 And the program can parse and execute the user's function. I'm looking for something similar to the eval command in Python. Thanks, David J. Sankel ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: video4linux
--- Martin Huschenbett <[EMAIL PROTECTED]> wrote: > Hi all, > > does anybody know how to read a single image from a > video4linux device under Haskell? > Thanks for all help, Hello, I think that the easiest way to do this would be to use the ffi to connect with C code that does this. David J. Sankel ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
ANNOUNCE: rsa-haskell 1.1.0
rsa-haskell 1.1.0 = This is an announcement for a version 1.1.0 of the rsa-haskell library/tools. Description: rsa-haskell is a haskell implementation of the RSA algorithm. It contains simple programs that are useful for encrypting/decrypting anything that can be piped from STDIN/STDOUT. rsa-haskell also has an easy-to-use rsa and number theory library. Changes: Added AddZeros and SubZeros programs to fix previous m>pq errors. Now rsa-haskell's test runs without known error. Huge speedup in the RSAcrypt program. Useage messages now show for all user errors. All programs now support the -h, -?, and --help options. For more information and download: http://www.electronconsulting.com/rsa-haskell/ Please email comments, bugs, etc. to [EMAIL PROTECTED] David J. Sankel ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: how to convert IO String to string (Simple answer)
--- Lu Mudong <[EMAIL PROTECTED]> wrote: > Thanks a lot for you guys' help. > > I am very new to haskell and tried some methods you > guys advised, doesn't > seem to work, i think i didn't do it properly, > here's my code and result, > hope you can point out what's wrong. thanks! > Lots of theory, here's some code: -- Begin code module Main() where import IO myReadFile :: String -> IO String myReadFile filename = readFile filename main :: IO () main = do s <- myReadFile "/etc/fstab" let length = doStuffWithNormalString s putStr "Length of File :" putStr (show length) putStr "\n" -- For example, count the number of characters doStuffWithNormalString :: String -> Int doStuffWithNormalString s = length s; -- End code My Explination: Basically, your program starts in a do loop. Anything that returns an IO something needs a <-. For example a <- someIOReturnValue And you can use a as a normal value w/o an IO type. Anything function that doesn't return the IO type needs a let a = someNormalFunction. And you can pretty much do what you want after you know these things. Oh yea, you can't do IO stuff in a non IO function. This is a pretty nasty part of learning haskell, but once you get used to it, you might actually like it. Later, David J. Sankel ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
ANNOUNCE: rsa-haskell 1.0.0
rsa-haskell 1.0.0 = This is an announcement for a version 1.0.0 of the rsa-haskell library/tools. Description: rsa-haskell is a haskell implementation of the RSA algorithm. It contains simple programs that are useful for encrypting/decrypting anything that can be piped from STDIN/STDOUT. rsa-haskell also has an easy-to-use rsa and number theory library. For more information and download: http://www.electronconsulting.com/rsa-haskell/ Please email comments, bugs, etc. to [EMAIL PROTECTED] David J. Sankel __ Do you Yahoo!? U2 on LAUNCH - Exclusive greatest hits videos http://launch.yahoo.com/u2 ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: finding ....
--- Pixel <[EMAIL PROTECTED]> wrote: > Lennart Augustsson <[EMAIL PROTECTED]> writes: > > > > Diego Yanivello wrote: > > > > > > > hi,is there (in Haskell) a function like > existFile :: FilePath -> > > > > IO (Bool) ? Thanks! > > > > Using such a function is generally a bad idea > because of race conditions. > > however, real world programs use those tests since > you don't need to care > *everytime* about race conditions. (of course using > this existFile before > creating a temporary file is wrong, but existFile > has *many* other > applications) Could someone post an example of the creation of a temporary file where race conditions are important? Thanks, David J. Sankel __ Do You Yahoo!? Yahoo! Sports - live college hoops coverage http://sports.yahoo.com/ ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: Help
--- "Juan M. Duran" <[EMAIL PROTECTED]> wrote: > Hi, I'm writting a small parser in Haskell and, when > it is all done, I get > the following problem: Type Binding. > > The thing is, I have 3 main functions: > 1) Read the file, its type is: [Char] ->IO [Char] > (see InputOutput.hs) > 2) Parse a string (using words and readDec), its > type is: Integral a => > [Char] -> [a] (see Parse.hs) > 3) Parse a list of integer, its type is: [Float] -> > [[Float]] > (Functions.hs) > > Now the problem is that I cannot run the first > function, then use its > results as an input of the second function and, > finally, its results as > the input of the third function. > > How can I fix this without modifing all my functions > because they, > independly, works fine. > I'm kinda confused with all the spanish and such, but isn't the solution something like this? main = do a <- function1 let b = function2 a let c = function3 a David J. Sankel __ Do You Yahoo!? Yahoo! Sports - Coverage of the 2002 Olympic Games http://sports.yahoo.com ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
