Re: [Haskell-cafe] Instantiation problem
Patrick, I find Andrew Frank's work on axiomatic specifications of GIS systems -- which the paper you cite is built on -- very confusing, or indeed, confused. They have a bunch of example like data Car = Car Color class Car a where carColor :: a - Color instance Car Car where carColor (Car c _) = c as if there is some kind of special logical interpretation of having a class Car in addition to the data type Car. As far as I remember, they interpret type classes as axioms. After reading it, without being an expert in either GIS or a logician, I came away thinking that they were mixing some very abstract ideas from object-oriented languages into Haskell. I find the presentations of type classes by e.g. Mark Jones, and the links between functional programming and logic from either the Curry-Howard correspondence or HOL-style reasoning (for instance, see the HOL light manual), somewhat crisper. Tom On Sun, Jan 30, 2011 at 10:27 AM, Patrick Browne patrick.bro...@dit.ie wrote: On 29/01/2011 20:56, Henning Thielemann wrote: Is there a reason why you use an individual type for every unit? The existing implementations of typed physical units only encode the physical dimension in types and leave the unit factors to the value level. I found this to be the most natural way. I am studying type classes using examples from the literature [1]. There is no particular intension to implement anything. I am confused about the unit function in the code below. My understanding is: The signature of the unit function is defined in the MetricDescription class. Any valid instantce of MetricDescription will respect the functional dependency (FD): The FD | description - unit is exactly the signature of the unit function. My confusions I do not understand the definitions of unit in the instances. I do not know how the constant 1 can be equated with a *type*, Where did 1 come from? I do not know how the constant 1 can be equated with *two distinct* definitions of the function uint and still produce the following correct results Ok, modules loaded: A. *A unit (LengthInMetres 7) Metre *A unit (LengthInCentimetres 7) Centimetre *A [1] http://ifgi.uni-muenster.de/~lutzm/odbase04_schade_et_al.pdf == module A where -- Each member of the Unit class has one operator convertFactorToBaseUnit -- that takes a measurement unit (say metre) and returns a conversion factor for that unit of measurement class Unit unit where convertFactorToBaseUnit :: unit - Double class (Unit unit) = MetricDescription description unit | description - unit where unit :: description - unit valueInUnit :: description - Double valueInBaseUnit :: description - Double valueInBaseUnit d = (convertFactorToBaseUnit(unit d)) * (valueInUnit d) data Dog = Dog deriving Show data Metre = Metre deriving Show data Centimetre = Centimetre deriving Show -- An instance for metres, where the convert factor is 1.0 instance Unit Metre where convertFactorToBaseUnit Metre = 1.0 -- An instance for centimetres, where the convert factor is 0.1 instance Unit Centimetre where convertFactorToBaseUnit Centimetre = 0.1 data LengthInMetres = LengthInMetres Double deriving Show data LengthInCentimetres = LengthInCentimetres Double deriving Show instance MetricDescription LengthInMetres Metre where valueInUnit (LengthInMetres d) = d unit l = Metre instance MetricDescription LengthInCentimetres Centimetre where valueInUnit (LengthInCentimetres d) = d unit l = Centimetre This message has been scanned for content and viruses by the DIT Information Services E-Mail Scanning Service, and is believed to be clean. http://www.dit.ie ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Cabal ignores ld-options? - 2011 remix
On Mon, 2011-01-31 at 01:13 -0500, Ryan Newton wrote: Ok, I've made some progress in the direction Duncan suggested. I can filter out the extra library before the postConf hook gets it. And calling make from the hooks is pretty easy. I've got a hack working that does allow full build/link/install given a hardcoded path (e.g. hack). It works by passing -Wl,-rpath=/opt/... directly through the .cabal file (ld-options). I need to un-hardcode that directory but I can't figure out how to achieve the same effect as that ld-options from my Setup.hs (I tried adding buildProgramArgs in the buildHook but no luck yet). Just modify the package description instead, e.g. in the configure step. The build prog args is intended for users, not for package authors. (It's so that cabal build --$PROG-options= works, and that's not something you're supposed to interfere with. Afterall, users are in control and can always add whatever options they want by adding wrapper scripts etc, this just makes it more convenient.) There's also the question of how to find the install dir so that rpath can be set to it. Unfortunately, I haven't been able to dig that out yet. When I try to use absoluteInstallDirs via something like below, I get this error: setup: internal error InstallDirs.libsubdir putStrLn$ Install dirs: ++ show (absoluteInstallDirs desc linfo NoCopyDest) You're doing the right thing, just don't look at the libsubdir or datasubdir after calling absoluteInstallDirs, because those do not make sense after making the paths absolute (they're inherently relative). The reason it's labelled as an internal error is because if cabal were ever to call those, then it would be an internal error. When you call it however, it's your fault ;-) Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: genprog-0.1
Jan, great, great work. Although I'm quite new to the Haskell (but experienced in a dozen of imperative languages and GP), I had no difficulties with adopting your example to my initial needs. Now I'm facing new problem: is it possible to create recursive program structures with your library (or using Haskell itself), so that you could simulate loop-like structures in the code ? Sorry if the answer to this question is obvious - I'm still getting used to the Haskell -) Thanks a lot for sharing this and congratulations. keep posting! -- View this message in context: http://haskell.1045720.n5.nabble.com/Re-ANNOUNCE-genprog-0-1-tp3310770p3364371.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Yesod and concurrency
Michael Snoyman mich...@snoyman.com wrote: On Mon, Jan 31, 2011 at 1:09 PM, Ertugrul Soeylemez e...@ertes.de wrote: Hello everybody, how well do WAI, Yesod and the 'persistent' package play with concurrency? For example, I'd like to write a program, which concurrently provides two related sites as well as a few background workers, which do something with the database. My idea would look something like this: main :: IO () main = withMyAppPool $ \pool - do forkIO $ worker1 ... -- background worker forkIO $ worker2 ... -- background worker forkIO $ worker3 ... -- background worker forkIO $ toWaiApp ... -- site 1 forkIO $ toWaiApp ... -- site 2 Will I run into problems with this? There should not be any issues, just make sure you compile with -threaded. The persistent database connection pool should work just fine for this. If you find any issues, please let me know, but I have not had trouble in the past. Thank you for your quick reply. How are my chances to get patches to Yesod incorporated into the mainstream code? Greets, Ertugrul -- nightmare = unsafePerformIO (getWrongWife = sex) http://ertes.de/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Yesod and concurrency
On Mon, Jan 31, 2011 at 2:28 PM, Ertugrul Soeylemez e...@ertes.de wrote: Michael Snoyman mich...@snoyman.com wrote: On Mon, Jan 31, 2011 at 1:09 PM, Ertugrul Soeylemez e...@ertes.de wrote: Hello everybody, how well do WAI, Yesod and the 'persistent' package play with concurrency? For example, I'd like to write a program, which concurrently provides two related sites as well as a few background workers, which do something with the database. My idea would look something like this: main :: IO () main = withMyAppPool $ \pool - do forkIO $ worker1 ... -- background worker forkIO $ worker2 ... -- background worker forkIO $ worker3 ... -- background worker forkIO $ toWaiApp ... -- site 1 forkIO $ toWaiApp ... -- site 2 Will I run into problems with this? There should not be any issues, just make sure you compile with -threaded. The persistent database connection pool should work just fine for this. If you find any issues, please let me know, but I have not had trouble in the past. Thank you for your quick reply. How are my chances to get patches to Yesod incorporated into the mainstream code? If it's a clean patch and does not break backwards compatibility: very high. If it's a clean patch that *does* break backwards compatibility: still good, but you'll have to wait till a major release. For not-so-clean patches, I suppose it depends on how dirty we're talking ;). Michael ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Loading bitmap with xlib
Francesco Mazzoli f at mazzo.li writes: At the end I gave up and I wrote the function myself: http://hpaste.org/43464/readbitmapfile ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] The implementation of Control.Exception.bracket
There is a common idiom used in Control.Concurrent libraries, as embodied in the implementation of bracket: http://www.haskell.org/ghc/docs/7.0-latest/html/libraries/base-4.3.0.0/src/Control-Exception-Base.html#bracket bracket before after thing = mask $ \restore - do a - before r - restore (thing a) `onException` after a _ - after a return r Is there any particular reason why bracket is not implemented as: bracket before after thing = mask $ \restore - do a - before r - restore (thing a) `finally` after a return r Is there some subtle semantic difference? Is there a performance difference? It seems like a trivial thing, but I am genuinely curious. Best, Leon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] The implementation of Control.Exception.bracket
On 31 January 2011 14:17, Leon Smith leon.p.sm...@gmail.com wrote:
Is there some subtle semantic difference? Is there a performance
difference? It seems like a trivial thing, but I am genuinely
curious.
According to my understanding the two should have equivalent
semantics. As for performance, I whipped up a trivial Criterion
microbenchmark and the version that doesn't use finally seems to
consistently benchmark 32ns (33%) faster than the version that does
use it, likely because it avoids a useless mask/restore pair.
(Note that this result is reversed if you compile without -O2, I guess
because -O2 optimises the library finally enough to overcome the
fact that it does an extra mask).
Code in the appendix.
Cheers,
Max
===
{-# LANGUAGE Rank2Types #-}
import Control.Exception
import Criterion.Main
{-# NOINLINE bracket_no_finally #-}
bracket_no_finally :: IO a - (a - IO b) - (a - IO c) - IO c
bracket_no_finally before after thing =
mask $ \restore - do
a - before
r - restore (thing a) `onException` after a
_ - after a
return r
{-# NOINLINE bracket_finally #-}
bracket_finally :: IO a - (a - IO b) - (a - IO c) - IO c
bracket_finally before after thing =
mask $ \restore - do
a - before
r - restore (thing a) `finally` after a
return r
{-# NOINLINE test_bracket #-}
test_bracket :: (forall a b c. IO a - (a - IO b) - (a - IO c) -
IO c) - IO ()
test_bracket bracket = bracket (return ()) (\() - return ()) (\() - return ())
main = defaultMain [
bench finally $ test_bracket bracket_finally
, bench no finally $ test_bracket bracket_no_finally
]
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[Haskell-cafe] Typing problem
I'm mapping a function over a list of data, where the mapping function is
determined from the data.
g f l = map (g l) l
So
g serialize prolog - [4,5,3,2,3,1]
But I'm having typing problems trying to do a similar thing with a function
that statistically normalizes data.
See:
http://people.revoledu.com/kardi/tutorial/Similarity/Normalization.html#Statistic
So
g normalize [2,5,3,2] -
[-0.7071067811865475,1.414213562373095,0.0,-0.7071067811865475]
Is my typing for normalize too loose. Should I be using Floating rather than
Num?
Michael
===Code==
{-
See Problem 42, pg. 63, Prolog by Example, Coelho Cotta
Generate a list of serial numbers for the items of a given list,
the members of which are to be numbered in alphabetical order.
*Main serialize prolog
[4,5,3,2,3,1]
*Main serialize int.artificial
[5,7,9,1,2,8,9,5,4,5,3,5,2,6]
*Main [prolog] = serialize
[4,5,3,2,3,1]
*Main [int.artificial] = serialize
[5,7,9,1,2,8,9,5,4,5,3,5,2,6]
-}
import Data.Map hiding (map)
import Data.List
{-
serialize :: [Char] - [Int]
serialize l = map (f l) l
where
f = ((!) . fromList . ((flip zip) [1..]) . (sort . nub))
-}
serialize :: (Ord a, Integral b) = [a] - a - b
serialize = ((!) . fromList . ((flip zip) [1..]) . (sort . nub))
g f l = map (f l) l
normalize :: (Num a, Num b) = [a] - a - b
normalize l = let (total,len) = sumlen l
avg = total/len
stdev = sqrt $ ((/) (len-1)) $ sum $ map ((** 2.0) .
(subtract avg)) l
in ((/) stdev) . (subtract avg)
sumlen :: (Num a, Integral b) = [a] - (a,b)
sumlen l = sumlen' l 0 0
where sumlen' [] sum len = (sum,len)
sumlen' (h:t) sum len = sumlen' t (sum+h) (len+1)
=
Prelude :r
[1 of 1] Compiling Main ( serialize2.hs, interpreted )
serialize2.hs:34:32:
Could not deduce (Integral a) from the context (Num a, Num b)
arising from a use of `sumlen' at serialize2.hs:34:32-39
Possible fix:
add (Integral a) to the context of
the type signature for `normalize'
In the expression: sumlen l
In a pattern binding: (total, len) = sumlen l
In the expression:
let
(total, len) = sumlen l
avg = total / len
stdev = sqrt
$ ((/) (len - 1)) $ sum $ map ((** 2.0) . (subtract avg)) l
in (/ stdev) . (subtract avg)
serialize2.hs:36:61:
Could not deduce (Floating a) from the context (Num a, Num b)
arising from a use of `**' at serialize2.hs:36:61-66
Possible fix:
add (Floating a) to the context of
the type signature for `normalize'
In the first argument of `(.)', namely `(** 2.0)'
In the first argument of `map', namely
`((** 2.0) . (subtract avg))'
In the second argument of `($)', namely
`map ((** 2.0) . (subtract avg)) l'
serialize2.hs:37:18:
Couldn't match expected type `b' against inferred type `a'
`b' is a rigid type variable bound by
the type signature for `normalize' at serialize2.hs:33:25
`a' is a rigid type variable bound by
the type signature for `normalize' at serialize2.hs:33:18
In the expression: (/ stdev) . (subtract avg)
In the expression:
let
(total, len) = sumlen l
avg = total / len
stdev = sqrt
$ ((/) (len - 1)) $ sum $ map ((** 2.0) . (subtract avg)) l
in (/ stdev) . (subtract avg)
In the definition of `normalize':
normalize l = let
(total, len) = sumlen l
avg = total / len
in (/ stdev) . (subtract avg)
Failed, modules loaded: none.
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Re: [Haskell-cafe] Typing problem
On Monday 31 January 2011 18:29:59, michael rice wrote: I'm mapping a function over a list of data, where the mapping function is determined from the data. g f l = map (g l) l g f l = map (f l) l probably So g serialize prolog - [4,5,3,2,3,1] But I'm having typing problems trying to do a similar thing with a function that statistically normalizes data. See: http://people.revoledu.com/kardi/tutorial/Similarity/Normalization.html# Statistic So g normalize [2,5,3,2] - [-0.7071067811865475,1.414213562373095,0.0,-0.7071067811865475] Is my typing for normalize too loose. You can omit the type signatures and see what the compiler infers as the type. In this case, normalize :: (Num a, Num b) = [a] - a - b normalize l = let (total,len) = sumlen l avg = total/len stdev = sqrt $ ((/) (len-1)) $ sum $ map ((** 2.0) . (subtract avg)) l in ((/) stdev) . (subtract avg) In the final result, I suppose it should be (/ stdev) and not ((/) stdev) [the latter is (stdev /), i.e. \x - stdev / x]. by sumlen's type, len has an Integral type. You want to use (/) to divide, which gives a Fractional constraint, (/) :: Fractional a = a - a - a Since it is not sensible for a type to be a member of both, the Fractional and Integral classes, you should convert len to the appropriate type with fromIntegral. For stdev, you call sqrt :: Floating a = a - a and (**) :: Floating a = a - a which means the list elements must have a type belonging to Floating (you could replace the (** 2.0) with (^ 2), which would probably be better, but the Floating constraint remains due to the sqrt). Finally, the resulting function is \x - (x - avg) / stdev, hence x must have the same type as abg and stdev, and the final result has the same type. Altogether, normalize :: Floating a = [a] - a - a normalize l = let (total, len0) = sumlen l len = fromIntegral len0 avg = total/len stdev = sqrt $ sum [(x-avg)^2 | x - l] / (len-1) in (/ stdev) . subtract avg but that gives nonsense if you pass a complex-valued list, so it might be better to restrict the type to normalize :: RealFloat a = [a] - a - a Should I be using Floating rather than Num? You have to, and one number type only (well, you could use two or three types if you compose with conversion functions, realToFrac for example). ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Typing problem
Michael,
just leaving out the type declaration for 'normalize', your module
complies fine and ghc infers the following type:
normalize :: (Integral a, Floating a) = [a] - a - a
Note that the context (Integral a, Floating a) cannot be met by any of
the standard types. (try in ghci: :i Integral and :i Floating)
So we have to apply a conversion function like this: (I just replaced
len by len' at all occurrences)
normalize l = let (total,len) = sumlen l
len' = fromIntegral len
avg = total/len'
stdev = sqrt $ ((/) (len'-1)) $ sum $ map ((** 2.0)
. (subtract avg)) l
in ((/) stdev) . (subtract avg)
yielding a type of
normalize :: (Floating b) = [b] - b - b
You could save the conversion by allowing a more liberal type for
'sumlen'. Without the type signature, it is inferred to
sumlen :: (Num t, Num t1) = [t] - (t, t1)
-- Steffen
On 01/31/2011 06:29 PM, michael rice wrote:
I'm mapping a function over a list of data, where the mapping function is
determined from the data.
g f l = map (g l) l
So
g serialize prolog - [4,5,3,2,3,1]
But I'm having typing problems trying to do a similar thing with a
function
that statistically normalizes data.
See:
http://people.revoledu.com/kardi/tutorial/Similarity/Normalization.html#Statistic
So
g normalize [2,5,3,2] -
[-0.7071067811865475,1.414213562373095,0.0,-0.7071067811865475]
Is my typing for normalize too loose. Should I be using Floating
rather than Num?
Michael
===Code==
{-
See Problem 42, pg. 63, Prolog by Example, Coelho Cotta
Generate a list of serial numbers for the items of a given list,
the members of which are to be numbered in alphabetical order.
*Main serialize prolog
[4,5,3,2,3,1]
*Main serialize int.artificial
[5,7,9,1,2,8,9,5,4,5,3,5,2,6]
*Main [prolog] = serialize
[4,5,3,2,3,1]
*Main [int.artificial] = serialize
[5,7,9,1,2,8,9,5,4,5,3,5,2,6]
-}
import Data.Map hiding (map)
import Data.List
{-
serialize :: [Char] - [Int]
serialize l = map (f l) l
where
f = ((!) . fromList . ((flip zip) [1..]) . (sort . nub))
-}
serialize :: (Ord a, Integral b) = [a] - a - b
serialize = ((!) . fromList . ((flip zip) [1..]) . (sort . nub))
g f l = map (f l) l
normalize :: (Num a, Num b) = [a] - a - b
normalize l = let (total,len) = sumlen l
avg = total/len
stdev = sqrt $ ((/) (len-1)) $ sum $ map ((** 2.0) .
(subtract avg)) l
in ((/) stdev) . (subtract avg)
sumlen :: (Num a, Integral b) = [a] - (a,b)
sumlen l = sumlen' l 0 0
where sumlen' [] sum len = (sum,len)
sumlen' (h:t) sum len = sumlen' t (sum+h) (len+1)
=
Prelude :r
[1 of 1] Compiling Main ( serialize2.hs, interpreted )
serialize2.hs:34:32:
Could not deduce (Integral a) from the context (Num a, Num b)
arising from a use of `sumlen' at serialize2.hs:34:32-39
Possible fix:
add (Integral a) to the context of
the type signature for `normalize'
In the expression: sumlen l
In a pattern binding: (total, len) = sumlen l
In the expression:
let
(total, len) = sumlen l
avg = total / len
stdev = sqrt
$ ((/) (len - 1)) $ sum $ map ((** 2.0) . (subtract
avg)) l
in (/ stdev) . (subtract avg)
serialize2.hs:36:61:
Could not deduce (Floating a) from the context (Num a, Num b)
arising from a use of `**' at serialize2.hs:36:61-66
Possible fix:
add (Floating a) to the context of
the type signature for `normalize'
In the first argument of `(.)', namely `(** 2.0)'
In the first argument of `map', namely
`((** 2.0) . (subtract avg))'
In the second argument of `($)', namely
`map ((** 2.0) . (subtract avg)) l'
serialize2.hs:37:18:
Couldn't match expected type `b' against inferred type `a'
`b' is a rigid type variable bound by
the type signature for `normalize' at serialize2.hs:33:25
`a' is a rigid type variable bound by
the type signature for `normalize' at serialize2.hs:33:18
In the expression: (/ stdev) . (subtract avg)
In the expression:
let
(total, len) = sumlen l
avg = total / len
stdev = sqrt
$ ((/) (len - 1)) $ sum $ map ((** 2.0) . (subtract
avg)) l
in (/ stdev) . (subtract avg)
In the definition of `normalize':
normalize l = let
(total, len) = sumlen l
avg = total / len
in (/ stdev) . (subtract avg)
Failed, modules loaded: none.
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Re: [Haskell-cafe] Haskell for children? Any experience?
On Thu, Jan 27, 2011 at 7:28 AM, aditya siram aditya.si...@gmail.com wrote: Ye gods! A B D [1] language for kids? At least give them a fighting chance [2] at becoming future developers. Haskell's immutability is good for mathematics but doing anything else takes a great deal of up-front patience and perseverance, two very rare qualities in that demographic if my own childhood is any indication. BTW I want to be wrong so if you do succeed with this I will feast on crow with gusto. IMO, the two very rare qualities part is a self-fulfilling prophecy. Didn't a lot of us spend endless hours tinkering with Linux configurations or seeing how many ways there were to use the debugger to make the computer crash when we were teenagers (if we were lucky enough to have computers as teenagers, anyway)? Kids -- and other people -- do amazing things when no one tells them it's hard. To the OP, I think teaching Haskell to 11-13 year olds should if anything be easier than teaching it to undergrads. At that age, they're less likely to have absorbed social math is hard messages and less likely to have absorbed Real-Programmer-ish ideas about what languages they're supposed to be programming in or what languages are practical. Sounds like a joy! Also, if you haven't, check out the book _Mindstorms_ by Seymour Papert -- the particular programming paradigm he advocates is different, but there should be some good fundamental ideas to inspire you. Cheers, Tim -- Tim Chevalier * http://cs.pdx.edu/~tjc/ * Often in error, never in doubt an intelligent person fights for lost causes,realizing that others are merely effects -- E.E. Cummings ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell WalkSat algorithm implementation
I need some help if possible with the following problem.The WalkSat algorithm takes a formula, a probability 0 = p = 1, and a boundary of maximum flips maxflips and returns a model that satisfies the formula or failure. The algorithm begins by assigning truth values to the atoms randomly, ie. generating a random model. Then it proceeds to flip the value of an atom from one of the unsatisfied clauses until it is able to find a model that satisfies the formula or reaches the maximum number of flips. In order to select which atom from the currently selected clause to flip, it follows two strategies: 1. Either flip any atom randomly. 2. Or flip the atom that maximizes the number of satisfied clauses in the formula. The choice to flip randomly is followed with probability p. 1.atomsClause :: Clause ! [Atom] This function must take a Clause and return the set of Atoms of that Clause. Note that the set should not contain any duplicates. 2. atoms :: Formula![Atom] This function must take a Formula return the set of Atoms of a Formula. Note that the set should not contain any duplicates. 3. isLiteral :: Literal ! Clause ! Bool This function returns True if the given Literal can be found within the Clause. 4. flipSymbol :: Model ! Atom ! Model This function must take a Model and an Atom and flip the truth value of the atom in the model. Now I've done the first 3 I need some help with the last one, Here is the code: module Algorithm where import System.Random import Data.Maybe import Data.List type Atom = String type Literal = (Bool,Atom) type Clause = [Literal] type Formula = [Clause] type Model = [(Atom, Bool)] type Node = (Formula, ([Atom], Model)) atomsClause :: Clause - [Atom] atomsClause = nub . map snd atoms :: Formula - [Atom] atoms =atomsClause . concat isLiteral :: Literal - Clause - Bool isLiteral (b,a) cs = or[x==b y==a|(x,y)-cs] flipSymbol :: Model - Atom - Model flipSymbol = undefined ---the last one Thank you. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] plugins and internal error: stg_ap_v_ret
Hi all,
I'm trying to convert wai-handler-devel to use plugins instead of
hint, but cannot even get some basic usages to work properly. I've put
together a minimal example that loads a WAI application from a
separate file and runs it, but this immediately causes the program to
crash saying:
loader: internal error: stg_ap_v_ret
(GHC version 6.12.3 for i386_unknown_linux)
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
Is this an actual bug in GHC, or am I misusing the plugins package?
The two source files:
MyModule.hs
{-# LANGUAGE OverloadedStrings #-}
module MyModule where
import Network.Wai
import Data.ByteString.Lazy.Char8 ()
myapp _ = responseLBS status200 [(Content-Type, text/plain)] myapp
loader.hs
import System.Plugins.Make
import System.Plugins.Load
import Network.Wai.Handler.Warp (run)
main :: IO ()
main = do
MakeSuccess _ obj - makeAll MyModule.hs []
LoadSuccess _ app - load_ obj [] myapp
run 3000 app
Thanks,
Michael
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Re: [Haskell-cafe] Haskell WalkSat algorithm implementation
On Mon, Jan 31, 2011 at 9:11 PM, Manolache Andrei-Ionut andressocrate...@yahoo.com wrote: I need some help if possible with the following problem.The WalkSat algorithm takes a formula, a probability 0 = p = 1, and a boundary of maximum flips maxflips and returns a model that satisfies the formula or failure. The algorithm begins by assigning truth values to the atoms randomly, ie. generating a random model. Then it proceeds to flip the value of an atom from one of the unsatisfied clauses until it is able to find a model that satisfies the formula or reaches the maximum number of flips. In order to select which atom from the currently selected clause to flip, it follows two strategies: 1. Either flip any atom randomly. 2. Or flip the atom that maximizes the number of satisfied clauses in the formula. The choice to flip randomly is followed with probability p. 1.atomsClause :: Clause ! [Atom] This function must take a Clause and return the set of Atoms of that Clause. Note that the set should not contain any duplicates. 2. atoms :: Formula![Atom] This function must take a Formula return the set of Atoms of a Formula. Note that the set should not contain any duplicates. 3. isLiteral :: Literal ! Clause ! Bool This function returns True if the given Literal can be found within the Clause. 4. flipSymbol :: Model ! Atom ! Model This function must take a Model and an Atom and flip the truth value of the atom in the model. Now I've done the first 3 I need some help with the last one, Here is the code: module Algorithm where import System.Random import Data.Maybe import Data.List type Atom = String type Literal = (Bool,Atom) type Clause = [Literal] type Formula = [Clause] type Model = [(Atom, Bool)] type Node = (Formula, ([Atom], Model)) atomsClause :: Clause - [Atom] atomsClause = nub . map snd atoms :: Formula - [Atom] atoms =atomsClause . concat isLiteral :: Literal - Clause - Bool isLiteral (b,a) cs = or[x==b y==a|(x,y)-cs] flipSymbol :: Model - Atom - Model flipSymbol = undefined ---the last one Thank you. Hi, I guess that flipSymbol m a = map f m where f (atom, value) = if a == atom then (atom, not value) else (atom, value) should do the trick. -- Mihai ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Typing problem
I hadn't considered the types of the functions I call in the function I'm trying to write, something not usually needed in loosely typed languages with coercion, but something I'm going to have to make a habit of doing. One more thing to add to the check list. Also, I had considered the numbers in the list to be integral if they didn't have decimal points, which inferred, for me, that polymorphic type a needed to be of a class that would accept either Integral or Floating values, i.e., Num. False reasoning. Thanks, all. Michael --- On Mon, 1/31/11, Daniel Fischer daniel.is.fisc...@googlemail.com wrote: From: Daniel Fischer daniel.is.fisc...@googlemail.com Subject: Re: [Haskell-cafe] Typing problem To: haskell-cafe@haskell.org Cc: michael rice nowg...@yahoo.com Date: Monday, January 31, 2011, 1:38 PM On Monday 31 January 2011 18:29:59, michael rice wrote: I'm mapping a function over a list of data, where the mapping function is determined from the data. g f l = map (g l) l g f l = map (f l) l probably So g serialize prolog - [4,5,3,2,3,1] But I'm having typing problems trying to do a similar thing with a function that statistically normalizes data. See: http://people.revoledu.com/kardi/tutorial/Similarity/Normalization.html# Statistic So g normalize [2,5,3,2] - [-0.7071067811865475,1.414213562373095,0.0,-0.7071067811865475] Is my typing for normalize too loose. You can omit the type signatures and see what the compiler infers as the type. In this case, normalize :: (Num a, Num b) = [a] - a - b normalize l = let (total,len) = sumlen l avg = total/len stdev = sqrt $ ((/) (len-1)) $ sum $ map ((** 2.0) . (subtract avg)) l in ((/) stdev) . (subtract avg) In the final result, I suppose it should be (/ stdev) and not ((/) stdev) [the latter is (stdev /), i.e. \x - stdev / x]. by sumlen's type, len has an Integral type. You want to use (/) to divide, which gives a Fractional constraint, (/) :: Fractional a = a - a - a Since it is not sensible for a type to be a member of both, the Fractional and Integral classes, you should convert len to the appropriate type with fromIntegral. For stdev, you call sqrt :: Floating a = a - a and (**) :: Floating a = a - a which means the list elements must have a type belonging to Floating (you could replace the (** 2.0) with (^ 2), which would probably be better, but the Floating constraint remains due to the sqrt). Finally, the resulting function is \x - (x - avg) / stdev, hence x must have the same type as abg and stdev, and the final result has the same type. Altogether, normalize :: Floating a = [a] - a - a normalize l = let (total, len0) = sumlen l len = fromIntegral len0 avg = total/len stdev = sqrt $ sum [(x-avg)^2 | x - l] / (len-1) in (/ stdev) . subtract avg but that gives nonsense if you pass a complex-valued list, so it might be better to restrict the type to normalize :: RealFloat a = [a] - a - a Should I be using Floating rather than Num? You have to, and one number type only (well, you could use two or three types if you compose with conversion functions, realToFrac for example). ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell WalkSat algorithm implementation
thank you -- View this message in context: http://haskell.1045720.n5.nabble.com/Haskell-WalkSat-algorithm-implementation-tp3365064p3365124.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Inheritance and Wrappers
tldr: Can I make arbitrary instances of one class instantiate another without using wrappers? I'm new to Haskell, and am trying to implement some simple typeclasses for doing algebra. For example I have type class (simplified for the sake of argument) class AbGroup a where add :: a - a - a I would like any type instantiating Num to also be an abelian group: instance (Num a) = AbGroup a where add i j = i+j, but this doesn't compile because a is a variable, not a type constructor(or something). The problem is fixed, in a sense, If I introduce a wrapper class data Wrapper a = Wrap a instance (Num a) = AbGroup (Wrapper a) where add (Wrap i) (Wrap j) = Wrap(i+j) However, this is clumsy. Is there something else I can do? Thanks! -- View this message in context: http://haskell.1045720.n5.nabble.com/Inheritance-and-Wrappers-tp3365126p3365126.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Inheritance and Wrappers
On 01/31/2011 08:58 PM, MattMan wrote:
[...]
data Wrapper a = Wrap a
instance (Num a) = AbGroup (Wrapper a) where
add (Wrap i) (Wrap j) = Wrap(i+j)
However, this is clumsy. Is there something else I can do? Thanks
This is the normal approach. You can do funny things with the
OverlappingInstances extension, but it is probably not what you want.
The problem is that the compiler only considers the heads of the
instance declarations when determining which instance to use for a
specific type. So an instance like this:
instance (Num a) = AbGroup a where ...
means: Some type matching 'a' (that is, any type) is an instance of
'AbGroup' if and only if it is an instance of 'Num'.
An additional instance like
instance AbGroup SomeData where ...
would then conflict with the instance above: As 'SomeData' in particular
matches the type 'a', the compiler does not know which one to choose.
You could argue that the latter is more specific than the former, so
the compiler should choose that one. This is exactly what
OverlappingInstances does, but it can have more, unwanted effects.
You can make your wrapper code less clumsy by deriving some instances
such as
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
data Wrapper a = Wrap a deriving (Eq, Ord, Read, Show, Num)
-- Steffen
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Re: [Haskell-cafe] Inheritance and Wrappers
On Monday 31 January 2011 20:58:02, MattMan wrote: tldr: Can I make arbitrary instances of one class instantiate another without using wrappers? I'm new to Haskell, and am trying to implement some simple typeclasses for doing algebra. For example I have type class (simplified for the sake of argument) class AbGroup a where add :: a - a - a I would like any type instantiating Num to also be an abelian group: instance (Num a) = AbGroup a where add i j = i+j, but this doesn't compile because a is a variable, not a type constructor(or something). The problem is fixed, in a sense, If I introduce a wrapper class data Wrapper a = Wrap a instance (Num a) = AbGroup (Wrapper a) where add (Wrap i) (Wrap j) = Wrap(i+j) However, this is clumsy. Is there something else I can do? Thanks! Not really. You could enable the FexibleInstances extension, then your first instance would compile. But it would mean 'every type is an instance of AbGroup, and if you try to use it with something that isn't also a Num, it won't compile, also you can't have any other instances', not what you want. You could then also enable OverlappingInstances, which would allow you to write other instances, but that extension is widely regarded as dangerous (have to confess, I forgot what the dangers were, one was that instance selection doesn't always do what you want/expect). Wrapper instances or specific instances are probably the best way (specific instances to be generated by a preprocessor or TH). ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Inheritance and Wrappers
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 1/31/11 15:24 , Daniel Fischer wrote: want. You could then also enable OverlappingInstances, which would allow you to write other instances, but that extension is widely regarded as dangerous (have to confess, I forgot what the dangers were, one was that instance selection doesn't always do what you want/expect). Instance selection will still not look at the context, so multiple instances would complain about needing IncoherentInstances, and if you add *that* then it does something like taking the first matching instance it finds (again, ignoring the context completely). - -- brandon s. allbery [linux,solaris,freebsd,perl] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.11 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk1HHNMACgkQIn7hlCsL25XFYgCgqLWUoZzYrZO54ydDY9kTa9RT 3VAAn0WgJzeWO5vvO4QP1pkEYL5tzxYB =+6Pz -END PGP SIGNATURE- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Inheritance and Wrappers
On Mon, 31 Jan 2011, MattMan wrote: I'm new to Haskell, and am trying to implement some simple typeclasses for doing algebra. For example I have type class (simplified for the sake of argument) class AbGroup a where add :: a - a - a I would like any type instantiating Num to also be an abelian group: instance (Num a) = AbGroup a where add i j = i+j, If all methods of AbGroup can be defined for all Num types - why do you want an AbGroup at all? You could simply write functions with Num constraint. You may be also interested in existing approaches to algebra in Haskell: http://www.haskell.org/haskellwiki/Mathematical_prelude_discussion ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Inheritance and Wrappers
On Mon, 31 Jan 2011, Brandon S Allbery KF8NH wrote: On 1/31/11 15:24 , Daniel Fischer wrote: want. You could then also enable OverlappingInstances, which would allow you to write other instances, but that extension is widely regarded as dangerous (have to confess, I forgot what the dangers were, one was that instance selection doesn't always do what you want/expect). Instance selection will still not look at the context, so multiple instances would complain about needing IncoherentInstances, and if you add *that* then it does something like taking the first matching instance it finds (again, ignoring the context completely). Since the original poster classified himself as new to Haskell, I'm afraid that advanced and dangerous extensions are not the appropriate answer. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] companies using Haskell or other FP languages near Rochester?
I'm an undergraduate CS student (4th year status) looking for an co-op or internship in the Rochester area. I'd really like to do something with functional programming or Haskell specifically, but I'm not sure if anyone in this area does that. Staying near Rochester is important because I'd also like to take one or two classes at my school (Rochester Institute of Technology) over the summer. Any ideas? -- Edward Amsden Undergraduate Computer Science Rochester Institute of Technology www.edwardamsden.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Packages all screwed up
Hello, I recently tried to upgrade some package (eg. yesod) and it seems that, in the process, I screwed up my Haskell packages setup. When I am trying to do a simple: ghc --make Crete1941 It fails with message: Loader\Communication.hs:14:7: Could not find module `System.Process': Use -v to see a list of the files searched for. which is quite annoying ! Is there a way to reconstruct a sane baseline ? Thanks in advance Arnaud PS: In case it might be helpful, here is the output of ghc-pkg check -v There are problems in package pandoc-1.6: dependency utf8-string-0.3.6-02c7018b15768d3d72b99557d0f847ff doesn't exist There are problems in package zip-archive-0.1.1.6: dependency binary-0.5.0.2-0da250ded3b79a6e76d15de8e7ffc885 doesn't exist dependency utf8-string-0.3.6-02c7018b15768d3d72b99557d0f847ff doesn't exist There are problems in package url-2.1.2: dependency utf8-string-0.3.6-02c7018b15768d3d72b99557d0f847ff doesn't exist There are problems in package filestore-0.3.4.3: dependency utf8-string-0.3.6-02c7018b15768d3d72b99557d0f847ff doesn't exist There are problems in package happstack-server-0.5.0.2: dependency utf8-string-0.3.6-02c7018b15768d3d72b99557d0f847ff doesn't exist There are problems in package happstack-data-0.5.0.2: dependency binary-0.5.0.2-0da250ded3b79a6e76d15de8e7ffc885 doesn't exist There are problems in package feed-0.3.7: dependency utf8-string-0.3.6-02c7018b15768d3d72b99557d0f847ff doesn't exist There are problems in package SHA-1.4.1.3: dependency binary-0.5.0.2-0da250ded3b79a6e76d15de8e7ffc885 doesn't exist There are problems in package hashed-storage-0.5.3: dependency binary-0.5.0.2-0da250ded3b79a6e76d15de8e7ffc885 doesn't exist There are problems in package yesod-0.6.0.2: dependency cereal-0.3.0.0-835aef1b61feb29c879c2cdae5c16608 doesn't exist dependency clientsession-0.4.0.3-83420d6960f048ed87e049bcfa4d3d35 doesn't exist dependency neither-0.1.0-50e3e802c117062181b91d4cbd45270b doesn't exist dependency wai-0.2.2-11adeb24d79e447264a1c6aa73a257e8 doesn't exist There are problems in package xss-sanitize-0.2.2: dependency utf8-string-0.3.6-02c7018b15768d3d72b99557d0f847ff doesn't exist There are problems in package web-routes-0.23.0: dependency utf8-string-0.3.6-02c7018b15768d3d72b99557d0f847ff doesn't exist There are problems in package wai-extra-0.2.4: dependency utf8-string-0.3.6-02c7018b15768d3d72b99557d0f847ff doesn't exist dependency wai-0.2.2-11adeb24d79e447264a1c6aa73a257e8 doesn't exist dependency zlib-bindings-0.0.0-c2a6f489bd57d072e884afc1d6466b99 doesn't exist There are problems in package snap-server-0.2.11: dependency cereal-0.3.0.0-835aef1b61feb29c879c2cdae5c16608 doesn't exist dependency monads-fd-0.1.0.2-8e71857db7c17ae96ca5bff72f20d9fa doesn't exist There are problems in package snap-core-0.2.11: dependency cereal-0.3.0.0-835aef1b61feb29c879c2cdae5c16608 doesn't exist dependency monads-fd-0.1.0.2-8e71857db7c17ae96ca5bff72f20d9fa doesn't exist There are problems in package pureMD5-2.1.0.2: dependency binary-0.5.0.2-0da250ded3b79a6e76d15de8e7ffc885 doesn't exist dependency cereal-0.3.0.0-835aef1b61feb29c879c2cdae5c16608 doesn't exist There are problems in package persistent-0.3.0.1: dependency neither-0.1.0-50e3e802c117062181b91d4cbd45270b doesn't exist There are problems in package hsx-0.7.0: dependency utf8-string-0.3.6-02c7018b15768d3d72b99557d0f847ff doesn't exist There are problems in package HStringTemplate-0.6.5: dependency utf8-string-0.3.6-02c7018b15768d3d72b99557d0f847ff doesn't exist There are problems in package HSlim-0.1: dependency utf8-string-0.3.6-02c7018b15768d3d72b99557d0f847ff doesn't exist There are problems in package hint-0.3.3.0: dependency utf8-string-0.3.6-02c7018b15768d3d72b99557d0f847ff doesn't exist There are problems in package haskeline-0.6.3.1: dependency utf8-string-0.3.6-02c7018b15768d3d72b99557d0f847ff doesn't exist There are problems in package happstack-state-0.5.0.2: dependency binary-0.5.0.2-0da250ded3b79a6e76d15de8e7ffc885 doesn't exist dependency happstack-data-0.5.0.2-80c87686add000961445ac7ad8f41385 doesn't exist dependency happstack-util-0.5.0.2-781b128492ee5ce69eb3c01f6e6a02bb doesn't exist There are problems in package happstack-ixset-0.5.0.2: dependency happstack-data-0.5.0.2-80c87686add000961445ac7ad8f41385 doesn't exist dependency happstack-util-0.5.0.2-781b128492ee5ce69eb3c01f6e6a02bb doesn't exist There are problems in package happstack-0.5.0.2: dependency happstack-data-0.5.0.2-80c87686add000961445ac7ad8f41385 doesn't exist dependency happstack-server-0.5.0.2-9d48ec4b8dd67d495020314c5d2b doesn't exist dependency happstack-util-0.5.0.2-781b128492ee5ce69eb3c01f6e6a02bb doesn't exist dependency utf8-string-0.3.6-02c7018b15768d3d72b99557d0f847ff doesn't exist There are problems in package crypto-api-0.1.2.4: dependency cereal-0.3.0.0-835aef1b61feb29c879c2cdae5c16608 doesn't exist There are problems in package
Re: [Haskell-cafe] Packages all screwed up
On Monday 31 January 2011 23:59:57, Arnaud Bailly wrote: Hello, I recently tried to upgrade some package (eg. yesod) and it seems that, in the process, I screwed up my Haskell packages setup. Big time. When I am trying to do a simple: ghc --make Crete1941 It fails with message: Loader\Communication.hs:14:7: Could not find module `System.Process': Use -v to see a list of the files searched for. Scary. Does 'ghc-pkg list process' list - no package process at all - one package process in the global db - more than one process (one in the global db) - process in user db but not global ? The first would mean your GHC is really borked and you'd need to reinstall. The second and third would mean there's hope, four looks like a reinstall again. Unfortunately, the error message lets me fear the first. which is quite annoying ! Is there a way to reconstruct a sane baseline ? 1. Check whether ghc itself is affected, rename (or move, or delete if you think it's not worth saving) the directory your user db is in (ghc-pkg list process should tell you where if you don't know), so ghc doesn't see it. ghc-pkg check. If nothing is reported as broken, try compiling a programme or two using only the core libs, if it works, you probably don't need to reinstall ghc, if not, you have to start from zero. 2. If ghc itself is okay, you can decide whether you want to start fresh, then delete the old directory and cabal install what you need/want. If you think trying to rescue what you have and is not broken is worth the effort, ghc-pkg unregister the broken packages and cabal install them again. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Packages all screwed up
On Mon, Jan 31, 2011 at 4:59 PM, Arnaud Bailly arnaud.oq...@gmail.com wrote: Hello, I recently tried to upgrade some package (eg. yesod) and it seems that, in the process, I screwed up my Haskell packages setup. When I am trying to do a simple: ghc --make Crete1941 What command(s) did you issue to upgrade some packages? Were you trying to do a user or global install? When ghc loads packages, I've had cases where packages in the user db would shadow packages in the global db, causing *other* packages in the global db to report as broken. Thanks, Antoine ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Inheritance and Wrappers
\quote Henning Thielemann wrote: If all methods of AbGroup can be defined for all Num types - why do you want an AbGroup at all? You could simply write functions with Num constraint. Well, I'd rather not have to implement (*), abs, etc on every abelian group. You may be also interested in existing approaches to algebra in Haskell: http://www.haskell.org/haskellwiki/Mathematical_prelude_discussion Yes, in fact I am! Thanks for the suggestion; it seems numeric-prelude does [most of] the things I want. Thanks all. -- View this message in context: http://haskell.1045720.n5.nabble.com/Inheritance-and-Wrappers-tp3365126p336.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] plugins and internal error: stg_ap_v_ret
Hi Michael,
plugins use it's own function instead GHC API, so it's easy to break
with new version GHC.
-- Andy
Michael Snoyman mich...@snoyman.com
writes:
Hi all,
I'm trying to convert wai-handler-devel to use plugins instead of
hint, but cannot even get some basic usages to work properly. I've put
together a minimal example that loads a WAI application from a
separate file and runs it, but this immediately causes the program to
crash saying:
loader: internal error: stg_ap_v_ret
(GHC version 6.12.3 for i386_unknown_linux)
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
Is this an actual bug in GHC, or am I misusing the plugins package?
The two source files:
MyModule.hs
{-# LANGUAGE OverloadedStrings #-}
module MyModule where
import Network.Wai
import Data.ByteString.Lazy.Char8 ()
myapp _ = responseLBS status200 [(Content-Type, text/plain)] myapp
loader.hs
import System.Plugins.Make
import System.Plugins.Load
import Network.Wai.Handler.Warp (run)
main :: IO ()
main = do
MakeSuccess _ obj - makeAll MyModule.hs []
LoadSuccess _ app - load_ obj [] myapp
run 3000 app
Thanks,
Michael
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Re: [Haskell-cafe] Loading bitmap with xlib
On 31 January 2011 21:40, Francesco Mazzoli f...@mazzo.li wrote: Francesco Mazzoli f at mazzo.li writes: At the end I gave up and I wrote the function myself: http://hpaste.org/43464/readbitmapfile cool ... the listed maintainer for the Xlib bindings is librar...@haskell.org. Perhaps you could prepare a patch and send it there? (does anyone know if there is an actual maintainer?) Conrad. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Automatically move cursor focus in split window in haskell-mode in emacs on load (C-c C-l) command?
I'm using haskell-mode-2.8.0 and emacs 22.2.1 on Ubuntu 9.10 The following elisp code works for me to change the focus to the GHCi buffer (window) after the C-c C-l command in Haskell Mode. Try this in your .emacs file. (defadvice inferior-haskell-load-file (after change-focus-after-load) Change focus to GHCi window after C-c C-l command (other-window 1)) (ad-activate 'inferior-haskell-load-file) I have this after the haskell mode configuration section of my .emacs file. Remeber to go to the Emacs-lisp menu and 'Byte-compile and Load' after adding the above code to your .emacs file. To understand what the elisp code is doing you can go to the help menu in emacs, then drill down via 'Search Documentation ' , then 'Find any object by name'. Which will put you in the mini-buffer. Type in either defadvice or ad-activate to see the documentation for these functions. If you are a little rusty on elisp this documentation may be a little hard to understand. Basically this is what's happening. The function that is bound to the C-c C-l command is inferior-haskell-load-file. Which is an elisp function name and part of the elisp haskell mode code. The defadvice is kind of overloading this function. We are telling emacs that 'after' executing the 'inferior-haskell-load-file' function, execute our new function who's name is 'change-focus-after-load'. The body of our function is just one expression (other-window 1). This is the kind of stuff that makes it easy to modify (hack) the functionality of emacs to do what you want. I hope this helps and enjoy hacking in Haskell Steven ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Cabal ignores ld-options? - 2011 remix
Oops, I guess I misinterpreted package description. It did sound a little dangerous ;-). What you suggested also worked. I'm in good shape now. Thanks again, -Ryan On Mon, Jan 31, 2011 at 11:24 AM, Duncan Coutts duncan.cou...@googlemail.com wrote: On Mon, 2011-01-31 at 09:52 -0500, Ryan Newton wrote: Victory! Thanks! Well.. mostly victory ;-). I've got it in a state where the .cabal file rewriting works if cabal configure is called separately from cabal build/install so that the latter reads the modified configuration file. Yikes! Don't actually modify the .cabal file on disk. I meant just modify the data structure that gets passed around. As for portability... I'm afraid I don't personally do any development on Windows. Presumably the goal is for hackage packages to work without requiring Cygwin/make/etc? Right. Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Splittable random numbers
Small update: I got the first results from the hardware accelerated version on a 3.33 ghz westmere machine. Right now it does twice as well as the Gladman software version, which is also twice as well as the System.Random stdgen, and 1000 times faster than a the Haskell implementation of AES that I got from the Crypto package: How many random numbers can we generate in a second on one thread? Cost of rdtsc (ffi call):84 Approx getCPUTime calls per second: 209,798 Approx clock frequency: 3,331,093,772 First, timing with System.Random interface: 76,811,104 random ints generated [constant zero gen] 14,482,725 random ints generated [System.Random stdGen] 16,061 random ints generated [PureHaskell/reference] 32,309 random ints generated [PureHaskell] 2,401,893 random ints generated [Gladman inefficient] 15,980,625 random ints generated [Gladman] 2,329,500 random ints generated [IntelAES inefficient] 32,383,799 random ints generated [IntelAES] Comparison to C's rand(): 71,392,408 random ints generated [rand/store in C loop] 71,347,778 random ints generated [rand in Haskell loop] 71,324,158 random ints generated [rand/store in Haskell loop] This is what Burton Smith originally thought, that AES based RNG would be pretty fast and even faster with hardware acceleration. -Ryan On Mon, Jan 31, 2011 at 1:25 AM, Ryan Newton new...@mit.edu wrote: Hi Cafe, I've included Gladman's efficient, portable C implementation of AES generating random numbers now, and the hardware-accelerated version is working too. I'm currently seeing higher throughput for even the software based version than the builtin stdGen: First, timing with System.Random interface: 13,051,964 random ints generated [System.Random stdGen] ~ 252 cycles/int 15,635 random ints generated [PureHaskell/reference] ~ 210,763 cycles/int 31,159 random ints generated [PureHaskell] ~ 105,757 cycles/int 2,180,488 random ints generated [Gladman inefficient] ~ 1,511 cycles/int 15,015,095 random ints generated [Gladman] ~ 219 cycles/int That seems like a good argument for cryptographic RNGs to me! I'm having a lot of trouble getting cabal to build/install it successfully. You can see what I've got there now. I'd be interested to know if anyone else can build it successfully. It should work -- but only by building the assembly code into a .so and assuming the build directory is /opt/intel-aes ;-). I don't have real numbers for the hardware version yet because the Westmere machine I'm logged into is redhat 5.4 and is giving me GLIBC_2.7 not found errors. You can run it for correctness purposes using an emulation tool called sde (software development emulator)http://software.intel.com/en-us/articles/intel-software-development-emulator/that's based on dynamic binary translation. -Ryan P.S. Checkout command: git clone git://github.com/rrnewton/intel-aes.git On Sat, Jan 29, 2011 at 8:52 AM, Ryan Newton rrnew...@gmail.com wrote: perhaps performance? Is this approach less robust with a faster, non-cryptographic RNG? Yes, I don't understand that either. Is there a reason that using a weaker PRNG in this case is WORSE than using it in the non-splitting case? Is that why there is more of an impetus to use the cryptographic approach in this case? Anyway, taking for granted that the Burton approach is a useful thing to have implemented, I started developing a package for this stuff -- AES based RNG including both a haskell implementation and wrapping an AESNI-based C one . I haven't posted it to Hackage yet, but you can find the git repository here: https://github.com/rrnewton/intel-aes If you build with cabal and run the benchmark-intel-aes-rng executable, it will give you a breakdown like this: How many random numbers can we generate in a second on one thread? Cost of rdtsc (ffi call):83 Approx getCPUTime calls per second: 205,640 Approx clock frequency: 3,306,891,339 First, timing with System.Random interface: 193,178,901 random ints generated [constant zero gen] 14,530,358 random ints generated [System.Random stdGen] 16,346 random ints generated [BurtonGenSlow/reference] 32,965 random ints generated [BurtonGenSlow] Comparison to C's rand(): 118,766,285 random ints generated [rand/store in C loop] 114,668,028 random ints generated [rand / Haskell loop] 114,675,116 random ints generated [rand/store Haskell] At the moment this is Haskell-only, I haven't included the wrapped Intel assembly code library yet. As you can see, the pure-Haskell AES based RNG (BurtonGenSlow) is pretty slow. Would anyone else be interested in running those RNG testing tools (diehard, big crush) on this to make sure it is working correctly? Also I'd be happy if
Re: [Haskell-cafe] Packages all screwed up
Hi, Thanks for your answers. I did cabal upgrade yesod As for the user/global issue, I think I tried a user install, this is default isn't it? Looks like I will have to reinstall everything :-( Arnaud On Tue, Feb 1, 2011 at 1:34 AM, Antoine Latter aslat...@gmail.com wrote: On Mon, Jan 31, 2011 at 4:59 PM, Arnaud Bailly arnaud.oq...@gmail.com wrote: Hello, I recently tried to upgrade some package (eg. yesod) and it seems that, in the process, I screwed up my Haskell packages setup. When I am trying to do a simple: ghc --make Crete1941 What command(s) did you issue to upgrade some packages? Were you trying to do a user or global install? When ghc loads packages, I've had cases where packages in the user db would shadow packages in the global db, causing *other* packages in the global db to report as broken. Thanks, Antoine ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
