Re: [Haskell-cafe] Difference between Lazy ByteStrings and Strings in alex
On a related topic, I think Duncan Coutts and Lennart Kolmodin have
worked on adding ByteString support to Alex. It seems to be available in
the current darcs version of Alex. You many want to check with them for
more details.
/Björn
Jefferson Heard wrote:
It was suggested that I might derive some performance benefit from using lazy
bytestrings in my tokenizer instead of regular strings. Here's the code that
I've tried. Note that I've hacked the basic wrapper code in the Lazy
version, so the code should be all but the same. The only thing I had to do
out of the ordinary was write my own 'take' function instead of using the
substring function provided by Data.Lazy.ByteString.Char8. The take function
I used was derived from the one GHC uses in GHC.List and produces about the
same code.
The non-lazy version runs in 38 seconds on a 211MB file versus the lazy
versions 41 seconds. That of course doesn't seem like that much, and in the
non-lazy case, I have to break the input up into multiple files, whereas I
don't have to in the lazy version -- this does not take any extra time. The
seconds do add up to a couple of hours for me, though once I'm done, and so
I'd like to understand why, when the consensus was that Data.ByteString.Lazy
might give me better performance in the end, it doesn't do so here.
I am running GHC 2.6 now, and am using -O3 as my optimization parameter. I'm
profiling the code now, but was wondering if there was any insight...
-- Jeff
Non-lazy version
{
module Main
where
import qualified FileReader
}
%wrapper basic
$letter = [a-zA-Z]
$digit = 0-9
$alphanum = [a-zA-Z0-9]
$punct = [\! \@ \# \$ \% \^ \ \* \( \) \_ \- \+ \= \{ \[ \} \] \\ \| \; \: \'
\ \, \. \? \/ \` \~]
$dec = \.
$posneg = [\- \+]
@date1 = jan($punct|uary)?\ $digit{1,2}(\,\ $digit{2,4})?
| feb($punct|ruary)?\ $digit{1,2}(\,\ $digit{2,4})?
| mar($punct|ch)?\ $digit{1,2}(\,\ $digit{2,4})?
| apr($punct|il)?\ $digit{1,2}(\,\ $digit{2,4})?
| may?\ $digit{1,2}(\,\ $digit{2,4})?
| jun($punct|e)?\ $digit{1,2}(\,\ $digit{2,4})?
| jul($punct|y)?\ $digit{1,2}(\,\ $digit{2,4})?
| aug($punct|ust)?\ $digit{1,2}(\,\ $digit{2,4})?
| sep($punct|tember)?\ $digit{1,2}(\,\ $digit{2,4})?
| sept($punct)?\ $digit{1,2}(\,\ $digit{2,4})?
| oct($punct|ober)?\ $digit{1,2}(\,\ $digit{2,4})?
| nov($punct|ember)?\ $digit{1,2}(\,\ $digit{2,4})?
| dec($punct|ember)?\ $digit{1,2}(\,\ $digit{2,4})?
@date2 = $digit{1,2} $punct $digit{1,2} $punct $digit{2,4}
@time = $digit{1,2} \: $digit{2} (am|pm)?
@word = $alphanum+
@number = $posneg? $digit+
| $posneg? $digit+ $dec $digit+
| $posneg? $digit+ (\,$digit{3})+
| $posneg? $digit? (\,$digit{3})+ $dec $digit+
$white = [\t\r\n\v\f\ ]
@doc = \ DOC \
@tag = \ $alphanum+ \
| \\/ $alphanum+ \
tokens :-
@doc{ \s - }
@tag;
$white+ ;
@time { \s - s }
@number { \s - s }
@word { \s - s }
$punct ;
. ;
{
printCount c [] = print c
printCount c (l:ls) = if l == then printCount (c+1) ls else printCount c ls
main = do
file - readFile trecfile1
printCount 0 (alexScanTokens file)
}
--
Version depending on ByteString.Lazy -- note that the grammar is the same, so
it has been omitted
--
... grammar ...
{
type AlexInput = (Char, -- previous char
B.ByteString) -- current input string
takebytes :: Int - B.ByteString - String
takebytes (0) _ =
takebytes n s = c : takebytes (n-1) cs
where c = B.index s 0
cs = B.drop 1 s
alexGetChar :: AlexInput - Maybe (Char,AlexInput)
alexGetChar (_, bytestring)
| bytestring == B.empty = Nothing
| otherwise = Just (c , (c,cs))
where c = B.index bytestring 0
cs = B.drop 1 bytestring
alexInputPrevChar :: AlexInput - Char
alexInputPrevChar (c,_) = c
alexScanTokens :: B.ByteString - [String]
alexScanTokens str = go ('\n',str)
where go inp@(_,str) =
case alexScan inp 0 of
AlexToken inp' len act - act (takebytes len str) : go inp'
AlexSkip inp' len - go inp'
AlexEOF - []
AlexError _ - error lexical error
printCount :: Int - [String] - IO ()
printCount c [] = print c
printCount c (l:ls) = if l == then printCount (c+1) ls else printCount c ls
main = do
file - B.readFile trecfile1
printCount 0 (alexScanTokens file)
}
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Re: [Haskell-cafe] Difference between Lazy ByteStrings and Strings in alex
On Tue, 2007-02-13 at 22:43 -0500, Jefferson Heard wrote: It was suggested that I might derive some performance benefit from using lazy bytestrings in my tokenizer instead of regular strings. Here's the code that I've tried. Note that I've hacked the basic wrapper code in the Lazy version, so the code should be all but the same. The only thing I had to do out of the ordinary was write my own 'take' function instead of using the substring function provided by Data.Lazy.ByteString.Char8. The take function I used was derived from the one GHC uses in GHC.List and produces about the same code. If you use the latest darcs version of alex and the basic-bytestring wrapper then you don't have to write any of your own take functions. Actually, lazy ByteString are still not as optimised as I would like. There are still too many indirections. That's something I'm working on at the moment. Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Network.CGI.Compat.pwrapper
Gracjan Polak wrote: 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 one to read which seem to be equivalent to stdin/stdout. But what about environment? How is it transfered, as someone ale pointed out pwrapper runs on different machine? I think your best bet is to read the code, it's not many lines. IIRC, pwrapper takes the environment variables from the local environment, which is rather useless. If you want a protocol for talking CGI over a socket, FastCGI does just that. /Björn ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re[2]: [Haskell-cafe] Summer of Code
Hello Donald, Wednesday, February 14, 2007, 1:51:26 AM, you wrote: 7 were successful, 2 were unsuccessful. can you please name successful projects and their download pages? -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to solve this problem?It's quite easy in PHP.
Hi
Eeek, a solution that does monadic maps and require's rank 2 types!
arr = [('a',1), ('b',2), ('c',3)]
showAll = lines (map showItem arr)
showItem (a,n) = a : = ++ show n
main = putStr showAll
I've broken this up a bit more than usual - most people would probably
just put showAll inside main, but this separates out the concepts. arr
is the data, which you could construct with a zip if that really is
all there is to it. showItem shows a single item, showAll shows them
all, and main just prints out the information.
And this solution is Haskell 98, anything that uses printf is Haskell' only.
Thanks
Neil
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Re: [Haskell-cafe] How to solve this problem?It's quite easy in PHP.
ndmitchell:
Hi
Eeek, a solution that does monadic maps and require's rank 2 types!
arr = [('a',1), ('b',2), ('c',3)]
showAll = lines (map showItem arr)
showItem (a,n) = a : = ++ show n
main = putStr showAll
I've broken this up a bit more than usual - most people would probably
just put showAll inside main, but this separates out the concepts. arr
is the data, which you could construct with a zip if that really is
all there is to it. showItem shows a single item, showAll shows them
all, and main just prints out the information.
And this solution is Haskell 98, anything that uses printf is Haskell' only.
Thanks
Neil
$ hugs +98
__ __ __ __ ___ _
|| || || || || || ||__ Hugs 98: Based on the Haskell 98 standard
||___|| ||__|| ||__|| __|| Copyright (c) 1994-2005
||---|| ___|| World Wide Web: http://haskell.org/hugs
|| || Report bugs to: hugs-bugs@haskell.org
|| || Version: March 2005 _
Haskell 98 mode: Restart with command line option -98 to enable extensions
Type :? for help
Hugs.Base :l Text.Printf
Text.Printf printf %d (1::Int) :: String
1
Fix YHC!
:-)
-- Don
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Re: [Haskell-cafe] How to solve this problem?It's quite easy in PHP.
Hi Don, Type :? for help Hugs.Base :l Text.Printf Text.Printf printf %d (1::Int) :: String 1 My bad - sorry, too many presentations/papers were people encoded printf using multi-ranked-generalised-associated types :) Fix Yhc! Fair point, should be as simple as compiling that file... Thanks Neil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to solve this problem?It's quite easy in PHP.
Using printf doesn't need Haskell'. I wrote to require only Haskell98.
-- Lennart
On Feb 14, 2007, at 11:36 , Neil Mitchell wrote:
Hi
Eeek, a solution that does monadic maps and require's rank 2 types!
arr = [('a',1), ('b',2), ('c',3)]
showAll = lines (map showItem arr)
showItem (a,n) = a : = ++ show n
main = putStr showAll
I've broken this up a bit more than usual - most people would probably
just put showAll inside main, but this separates out the concepts. arr
is the data, which you could construct with a zip if that really is
all there is to it. showItem shows a single item, showAll shows them
all, and main just prints out the information.
And this solution is Haskell 98, anything that uses printf is
Haskell' only.
Thanks
Neil
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Re: [Haskell-cafe] A new code search engine
On 14/02/07, Stephane Bortzmeyer [EMAIL PROTECTED] wrote: http://www.krugle.com/ Nice :-) Unlike Google, you can specify Haskell as a language. Google CodeSearch is pretty handy though: http://www.google.com/codesearch?q=lang%3Ahaskell it seems to return code with good relevence, and can look for specific licenses, but doesn't search on the structure of the code. Sometimes I find these tools useful for finding examples of how people actually use particular functions in the wild :-) cheers, Conrad. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Calendar Dates before the epoch
Bjorn Bringert-2 wrote: Use the time package (Data.Time.*). time-1.0 is in GHC 6.6 extralibs, and available from Hackage (http://hackage.haskell.org/cgi-bin/hackage-scripts/package/time-1.0) and the development version lives at http://darcs.haskell.org/packages/time/ Thanks Björn Jim -- View this message in context: http://www.nabble.com/Calendar-Dates-before-the-epoch-tf3221685.html#a8968473 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] LugRadio talk
So which one of you wonderful people volunteered to give a talk on Haskell at the coming LugRadio Live? I'm afraid I didn't catch the name, though it might have been a Magnus something? It might be enough to make me go if I knew there would be some funky Haskelling going on. Cheers, D. -- Dougal Stanton ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] A new code search engine
On 2/14/07, Stephane Bortzmeyer [EMAIL PROTECTED] wrote: http://www.krugle.com/ Unlike Google, you can specify Haskell as a language. It is true that you can't directly specify the programming language with Google. But you can specify the filetype, i.e. hs or lhs, with Google. To do this, just add `filetype:hs` to you search. And according to my initial tests, Google still wins. Adam ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] LugRadio talk
Dougal Stanton wrote: So which one of you wonderful people volunteered to give a talk on Haskell at the coming LugRadio Live? I'm afraid I didn't catch the name, though it might have been a Magnus something? It might be enough to make me go if I knew there would be some funky Haskelling going on. I heard it as Magnus too, a Swedish name. Sounds interesting indeed, LugRadio Live 2007, 7th-8th July 2007, The Lighthouse, Fryer Street, Wolverhampton, UK. Cheers, Lennart Kolmodin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Where can I find XmlRpc package?
http://www.cs.chalmers.se/~bringert/darcs/blob/Makefile BlobXmlRpc: GHCFLAGS += -package XmlRpc I can't find XmlRpc,so I use haxr instead,but it doesn't work. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Where can I find XmlRpc package?
On Feb 14, 2007, at 22:50 , keepbal wrote: http://www.cs.chalmers.se/~bringert/darcs/blob/Makefile BlobXmlRpc: GHCFLAGS += -package XmlRpc I can't find XmlRpc,so I use haxr instead,but it doesn't work. haxr is the new name for the XmlRpc package, so changing -package XmlRpc to -package haxr should work. If it doesn't, please include the information needed to figure out what's happening, for example what you tried and what happened (error messages etc.). Blob is quite old by the way. I can hardly remember what it does any more. /Björn___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Where can I find XmlRpc package?
BlobXmlRpc.hs:36:19: parse error on input `$' make: *** [BlobXmlRpc] Error 1 2007/2/15, Bjorn Bringert [EMAIL PROTECTED]: On Feb 14, 2007, at 22:50 , keepbal wrote: http://www.cs.chalmers.se/~bringert/darcs/blob/Makefile BlobXmlRpc: GHCFLAGS += -package XmlRpc I can't find XmlRpc,so I use haxr instead,but it doesn't work. haxr is the new name for the XmlRpc package, so changing -package XmlRpc to -package haxr should work. If it doesn't, please include the information needed to figure out what's happening, for example what you tried and what happened (error messages etc.). Blob is quite old by the way. I can hardly remember what it does any more. /Björn ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Programming an Evaluation Context
Hi there, in structural operational semantics, an evaluation context is often used to decompose an expression into a redex and its context. In a formal semantics on paper, an expression can just be pattern matched over the grammar of an evaluation context. If one wants to implement such a semantics in the form of an interpreter, I could not come up with a similarly nice solution. I have declared two separate data types (one for expressions, and one for evaluation contexts) and explicit functions to convert an expression into a (evaluation context, redex) pair. For example, I could have data Expr = Val Int | Plus Expr Expr and data Ctx = Hole | CPlusl Ctx Expr | CPlusr Int Expr Are there any tricks to mimick more closely what is going on in the formal semantics? Klaus ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.ByteString.Lazy.Char8 and finding substrings
magnus: I'm curious, why doesn't Data.ByteString.Lazy.Char8 have the functions for searching for substrings that Data.ByteString.Char8 has (isPrefixOf, isSuffixOf, isSubstringOf, findSubstring and findSubstrings)? Sorry for the delay. The reason they're missing is that no one implemented it. Would be nice to have though. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Programming an Evaluation Context
On 2/14/07, Klaus Ostermann [EMAIL PROTECTED] wrote: in structural operational semantics, an evaluation context is often used to decompose an expression into a redex and its context. Have you seen http://citeseer.ist.psu.edu/mcbride01derivative.html The Derivative of a Regular Type is its Type of One-Hole Contexts Jim ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
