Re: [Haskell-cafe] Re: Haskell version of Norvig's Python Spelling Corrector
Pete Kazmier wrote: train:: [B.ByteString] - WordFreq train words = frequencyMap where frequencyMap = foldr incWordCount M.empty words incWordCount w m = M.insertWith (+) w 1 m So is 'incWordCount' strict in its second argument? I'm still not sure exactly what that means. Yes. incWordCount is strict in its second argument since incWordCount x undefined == undefined Of course you cannot see that from the definition of incWordCount alone, this depends on the behavior of M.insertWith. According to the wiki page, if it is strict in the second argument, I should have used foldl' instead of foldr. Remember that the difference between foldr and foldl is not one between left and right; both have to recurse from the left. But foldr is normal recursion, while foldl is accumulator recursion. You obviously wanted an accumulator, and it should usually be strictly evaluated. There is another bug of this sort in your code. Consider incWordCount w m = M.insertWith (+) w 1 m There is no reason to evaluate the sum inside the map, instead an unevaluated thunk is put in there. Unfortunately, you need to take the long way of using M.lookup and M.insert to build a strict replacement for M.insertWith. (A strict variant of Data.Map would be useful here, unfortunately, there is none.) -Udo -- Streitigkeiten dauerten nie lange, wenn nur eine Seite Unrecht hätte. -- de la Rochefoucauld signature.asc Description: Digital signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] HXT namespace problem
Hi all,
I'm currently trying to generate XML documents with HXT. Everything went
well but I can't figure out how to generate the xmlns:... attributes
for the namespaces.
My code looks like:
runX $ constA (request TableListRequest) root [] [writeA]
writeDocument [(a_indent,v_1)] -
where writeA generates the actual content. This code generates something
like:
?xml version=1.0 encoding=UTF-8?
soapenv:Envelope
soapenv:Body
request:tablelist/
/soapenv:Body
/soapenv:Envelope
But I want it with XML namespaces, i.e.:
?xml version=1.0 encoding=UTF-8?
soapenv:Envelope
xmlns:soapenv=http://schemas.xmlsoap.org/soap/envelope/;
xmlns:request=http://www.officematic.de/domas/request;
soapenv:Body
request:tablelist/
/soapenv:Body
/soapenv:Envelope
I tried using uniqueNamespaces and uniqueNamespacesFromDeclAndQNames
but neither worked. Maybe I used them in the wrong part of code.
The tree representation my document looks like:
---XTag /
|
+---XTag {http://schemas.xmlsoap.org/soap/envelope/}soapenv:Envelope;
|
+---XTag {http://schemas.xmlsoap.org/soap/envelope/}soapenv:Body;
|
+---XTag
{http://www.officematic.de/domas/request}request:tablelist;
and for me this looks like if there is enough namespace information
provided.
I would appreciate any help,
Martin.
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[Haskell-cafe] Re: Compilling GHC on Vista
I still get the same message even with these instructions. I guess it may be due to some Vista security checking... Cheers, Monique On 4/24/07, Simon Marlow [EMAIL PROTECTED] wrote: Tom Schrijvers wrote: Here's the more complete error message: configure:3321: checking for C compiler default output file name configure:3348: c:/MinGW/bin/gccconftest.c 5 ld: /mingw/lib/crt2.o: No such file: No such file or directory configure:3351: $? = 1 configure:3389: result: configure: failed program was: configure:3396: error: C compiler cannot create executables See `config.log' for more details. Do make sure that MingW's bin/ and libexec/gcc/mingw32/3.4.2/ are the very first two in your path. I get the same error message if I don't do that. Hi Tom - would you mind adding the right incantation to the Vista instructions at the top of http://hackage.haskell.org/trac/ghc/wiki/Building/Windows? Cheers, Simon -- __ Monique Monteiro, MSc MCP .NET Framework 2.0 / SCJP / IBM OOAD Project Manager Recife Microsoft Innovation Center +55 81 34198137 http://www.cin.ufpe.br/~mlbm http://thespoke.net/blogs/moniquelouise/default.aspx [EMAIL PROTECTED] MSN: [EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Is Template Haskell a suitable macro language?
I'm finding myself dealing with several large abstract syntax trees that are very similar in nature. The constructor names would be the same or one type may be a small extension of another. This is something that I wouldn't worry about with Lisp, for example, as I would create a bunch of macros for creating syntax trees and reuse them all over. I cannot do this in Haskell, though, as my macros are functions and so I must repeat them for every AST since they return different types. I'm wondering if Template Haskell is a suitable replacement for Lisp macros. What is the consensus? Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Newbie seeking advice regarding data structure for a tricky algorithm
Hi Toby, On 4/24/07, Toby Hutton [EMAIL PROTECTED] wrote: Hi, I'm trying to implement a fast kd-tree in Haskell. http://en.wikipedia.org/wiki/Kd-tree It's a binary tree representing space partitions. Trees are pretty easy to implement in haskell, due to their inherent recursive nature. For example, you can do something like this: data Tree a = Node a [Tree a] Then the elements of the list are just the children subtrees of the current node. This is the approach taken by http://haskell.org/ghc/docs/latest/html/libraries/base/Data-Tree.html for example. I personally think this is easier than trying to define an actual binary tree. With this approach, the algorithms mentioned in the wikipedia article above should be relatively straight-forward to implement. As for the paper cited, and the 'analogous' algorithm, you lost me. I don't see what the algorithm you gives has to do with the problem, so I'm quite confused. My suggestion would be to try to translate one of the algorithms from wikipedia, and use that. If you can't work out how to do this, feel free to check back with me and/or the list. Good luck! [snip] Andrew ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] faster factorial function via FFI?
On Mon, 23 Apr 2007 at 04:36PM -0700, Stefan O'Rear wrote: I'm finding the number of set partitions that correspond to a certain integer partition. If p = p_1, p_2,...,p_k is an integer partition of n, then there are n! -- p_1! * p_2! * ... * p_k! * 1^c_1 * ... * k^c_k That formula isn't even correct. Consider p = replicate n 1, that is n partitions each of size 1. There is only one way to do this - put each element in its own partition. However, your formula gives: Correct, the formula is incorrect. :) The i^c_i terms need to be c_i!. (I got it right in my code, though.) Dan -- Ceci n'est pas une .signature. signature.asc Description: Digital signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Is Template Haskell a suitable macro language?
On Tue, 24 Apr 2007 14:23:47 +0100
Joel Reymont [EMAIL PROTECTED] wrote:
I'm finding myself dealing with several large abstract syntax trees
that are very similar in nature. The constructor names would be the
same or one type may be a small extension of another.
This is something that I wouldn't worry about with Lisp, for
example, as I would create a bunch of macros for creating syntax
trees and reuse them all over. I cannot do this in Haskell, though,
as my macros are functions and so I must repeat them for every AST
since they return different types.
I'm wondering if Template Haskell is a suitable replacement for Lisp
macros.
What is the consensus?
I saw your earlier post on abstract syntax trees, and I have indeed
been using Template Haskell for processing syntax trees. (Sorry I
didn't reply earlier.) It works quite well, yes.
Here's my success story. Basically I have two modules, Abstract and
Concrete, which define data types for abstract and concrete syntax
respectively. The Abstract module also contains code to convert
concrete syntax (i.e. what comes out of the parser) into abstract
syntax, and the code that just does copying (i.e. the boilerplate code)
is generated by Template Haskell code.
What I do looks like this:
$(let
preprocess :: [Dec] - Q [Dec]
-- definition omitted
in preprocess =
[d|type Param = (Ident, Term)
data FixBody = FixBody Ident [Param] (Maybe Annotation)
(Maybe Term) Term deriving (Typeable, Data, Eq)
data MatchItem = MatchItem Term (Maybe Ident) (Maybe Term)
deriving (Typeable, Data, Eq)
data IdentWithParams = IdentWithParams Ident [Param] (Maybe
Term) deriving (Typeable, Data, Eq)
class Abstraction c a {- | c - a -} where { abstractL ::
Monad m = c - StateT [(Ident,Term)] m a }
#include common2.inc
|])
Let me explain what's going on here, starting from the bottom. The
order of these parts is very important! The #include common2.inc
includes the type definitions which are common to both modules. (I
actually maintain a file common.inc and then that is preprocessed to
replace newlines with semicolons, in order to avoid the problem that
would otherwise occur that the file would be included at the wrong
identation level. Although the file is still included at the wrong
indentation level, apparently the use of semicolons mollifies ghc!) The
reason why I don't just put the stuff in common2.inc into another
module is because it refers to types that are defined *differently* in
each syntax! So I really am using cpp [actually, cpphs] for an
appropriate purpose here.
The class Abstraction defines a method abstractL. It is defined for
every concrete syntax data type and specifies how to translate that
type into abstract syntax (except the top-level which is handled
differently). The fundep is commented out because (a) ghc rejected it
and (b) I didn't need it anyway.
The preprocess function then takes all of the decls between [d| and |]
as input, passes through the declarations before the class declaration
(i.e. the ones that are not the same) without looking at them any
further, and then generates instances of the class for each data
declaration given below the class (i.e. all the types which are in
common, where only automatic copying code needs to be generated). It
also passes through all of the declarations given as input.
Why not simply put the initial declarations at the top of the file?
Well, ghc rejects that, if I remember correctly, because they refer to
other types which have yet to be generated (well, passed through) by
Template Haskell. Template Haskell seems to break the general principle
in Haskell that one can refer to a declaration in the same module,
textually before that declaration.
--
Robin
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Re: [Haskell-cafe] Re: Compilling GHC on Vista
I still get the same message even with these instructions. I guess it may be due to some Vista security checking... Do you still get the same error message in your config.log now? Or a different one? There is also an error on Vista with checking whether a file is executable. I don't know whether there's already a solution for that in the repository? Tom Cheers, Monique On 4/24/07, Simon Marlow [EMAIL PROTECTED] wrote: Tom Schrijvers wrote: Here's the more complete error message: configure:3321: checking for C compiler default output file name configure:3348: c:/MinGW/bin/gccconftest.c 5 ld: /mingw/lib/crt2.o: No such file: No such file or directory configure:3351: $? = 1 configure:3389: result: configure: failed program was: configure:3396: error: C compiler cannot create executables See `config.log' for more details. Do make sure that MingW's bin/ and libexec/gcc/mingw32/3.4.2/ are the very first two in your path. I get the same error message if I don't do that. Hi Tom - would you mind adding the right incantation to the Vista instructions at the top of http://hackage.haskell.org/trac/ghc/wiki/Building/Windows? Cheers, Simon -- __ Monique Monteiro, MSc MCP .NET Framework 2.0 / SCJP / IBM OOAD Project Manager Recife Microsoft Innovation Center +55 81 34198137 http://www.cin.ufpe.br/~mlbm http://thespoke.net/blogs/moniquelouise/default.aspx [EMAIL PROTECTED] MSN: [EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Tom Schrijvers Department of Computer Science K.U. Leuven Celestijnenlaan 200A B-3001 Heverlee Belgium tel: +32 16 327544 e-mail: [EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Compilling GHC on Vista
For backward compatibility reasons, I'm using GHC 6.2.2. So, if there is already a solution for this issue in the GHC repository, please let me know how to add it manually. I don't have problems with ./configure on Windows XP. On 4/24/07, Tom Schrijvers [EMAIL PROTECTED] wrote: I still get the same message even with these instructions. I guess it may be due to some Vista security checking... Do you still get the same error message in your config.log now? Or a different one? There is also an error on Vista with checking whether a file is executable. I don't know whether there's already a solution for that in the repository? Tom Cheers, Monique On 4/24/07, Simon Marlow [EMAIL PROTECTED] wrote: Tom Schrijvers wrote: Here's the more complete error message: configure:3321: checking for C compiler default output file name configure:3348: c:/MinGW/bin/gccconftest.c 5 ld: /mingw/lib/crt2.o: No such file: No such file or directory configure:3351: $? = 1 configure:3389: result: configure: failed program was: configure:3396: error: C compiler cannot create executables See `config.log' for more details. Do make sure that MingW's bin/ and libexec/gcc/mingw32/3.4.2/ are the very first two in your path. I get the same error message if I don't do that. Hi Tom - would you mind adding the right incantation to the Vista instructions at the top of http://hackage.haskell.org/trac/ghc/wiki/Building/Windows? Cheers, Simon -- __ Monique Monteiro, MSc MCP .NET Framework 2.0 / SCJP / IBM OOAD Project Manager Recife Microsoft Innovation Center +55 81 34198137 http://www.cin.ufpe.br/~mlbm http://thespoke.net/blogs/moniquelouise/default.aspx [EMAIL PROTECTED] MSN: [EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Tom Schrijvers Department of Computer Science K.U. Leuven Celestijnenlaan 200A B-3001 Heverlee Belgium tel: +32 16 327544 e-mail: [EMAIL PROTECTED] -- __ Monique Monteiro, MSc MCP .NET Framework 2.0 / SCJP / IBM OOAD Project Manager Recife Microsoft Innovation Center +55 81 34198137 http://www.cin.ufpe.br/~mlbm http://thespoke.net/blogs/moniquelouise/default.aspx [EMAIL PROTECTED] MSN: [EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Haskell version of Norvig's Python Spelling Corrector
Udo Stenzel wrote: There is another bug of this sort in your code. Consider incWordCount w m = M.insertWith (+) w 1 m There is no reason to evaluate the sum inside the map, instead an unevaluated thunk is put in there. Would not Data.Map.insertWith' do the trick? b ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: IDE support
Claus Reinke [EMAIL PROTECTED] writes: I use emacs exclusively for hacking Haskell, but I wanted to see if it's possible to connect to the shim server-process from vim and started working on omnicompletion: http://shim.haskellco.de/trac/attachment/wiki/ScreenShots/vim-shim.png http://shim.haskellco.de/trac/wiki/ShimVim http://darcsweb.haskellco.de/darcsweb.cgi?r=shim;a=tree;f=/vim I don't think I will spend much more time working on this, but if anyone wants to try it out or improve it, I would be happy to answer questions and review patches. thanks, i too had been wondering about the vim and part of shim, especially about the interprocess communication. you're using vim's python embedding for that, but many vim users won't have python. I'm not sure if it's possible to use the vim scripting language for that, but i used the python embedding so that I could base everything on the python omnicompletion. more importantly: is that python solution (using unix sockets portable, ie, would it work for windows vim users if they were asked to install python for that purpose? I don't think it's portable, but Tim Newsham added support for TCP sockets to the haskell and emacs side and it should be pretty easy to adapt the python vim script. Of course, you have to be careful with TCP since you can't use file permissions to make sure that nobody else connects to the socket. Thanks, Benedikt ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Is Template Haskell a suitable macro language?
Magnus Jonsson wrote: I have the same problem too when using Haskell. The more I try to enforce static guarantees the more I get lots of datatypes that are similar except for one or two constructors. The best way I have found to avoid this is to simply give up on some of the static guarantees and just use one datatype that contains all the constructors. Less static guarantees but also less needless type coaxing between 90% similar types. I haven't tried using macros. In Ocaml, you can frequently use polymorphic variants to get the same effect. Which means that if you are willing to do enough type-class-hackery, it should, in principle, be possible to do the same in Haskell. But it sure isn't as convenient! This all points to some clear need for more ``flavours'' of polymorphism being needed (in Haskell), to be able to express *in the type system* what TH allows you to say outside. Jacques ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Is Template Haskell a suitable macro language?
On 4/24/07, Jacques Carette [EMAIL PROTECTED] wrote: In Ocaml, you can frequently use polymorphic variants to get the same effect. Which means that if you are willing to do enough type-class-hackery, it should, in principle, be possible to do the same in Haskell. But it sure isn't as convenient! You seem to imply that there is an encoding of polymorphic variants in Haskell using type classes. While I know that it's possible to achieve similar effects using type classes I haven't seen a direct encoding. If there is such an encoding I would be very interested to hear about it. This all points to some clear need for more ``flavours'' of polymorphism being needed (in Haskell), to be able to express *in the type system* what TH allows you to say outside. I totally agree with this. Cheers, Josef ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Is Template Haskell a suitable macro language?
Josef Svenningsson wrote: On 4/24/07, Jacques Carette [EMAIL PROTECTED] wrote: In Ocaml, you can frequently use polymorphic variants to get the same effect. Which means that if you are willing to do enough type-class-hackery, it should, in principle, be possible to do the same in Haskell. But it sure isn't as convenient! You seem to imply that there is an encoding of polymorphic variants in Haskell using type classes. While I know that it's possible to achieve similar effects using type classes I haven't seen a direct encoding. If there is such an encoding I would be very interested to hear about it. As usual, look for a solution from Oleg: http://www.haskell.org/pipermail/haskell/2006-July/018172.html There was also a proposal by Koji Kagawa (published at Haskell '06) http://portal.acm.org/citation.cfm?id=1159842.1159848coll=dl=ACMtype=seriesidx=1159842part=ProceedingsWantType=Proceedingstitle=HaskellCFID=15151515CFTOKEN=6184618 Jacques ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] faster factorial function via FFI?
A thing of beauty is a joy forever. Simple, fast, elegant. If I learn any more from this list, someone is going to start charging me tuition! :) Dan [EMAIL PROTECTED] wrote: G'day all. Quoting Dan Weston [EMAIL PROTECTED]: Why all the fuss? n! is in fact very easily *completely* factored into prime numbers [...] It's even easier than that. primePowerOf :: Integer - Integer - Integer primePowerOf n p = (n - s p n) `div` (p-1) where s p 0 = 0 s p n = let (q,r) = n `divMod` p in s p q + r factorisedFactorial :: Integer - [(Integer,Integer)] factorisedFactorial n = [ (p, primePowerOf n p) | p - primesUpTo n ] factorial :: Integer - Integer factorial = product . zipWith (^) . factorisedFactorial (Implement primesUpTo using your favourite prime sieve.) Manipulating prime factors like this is sometimes MUCH faster than computing products for this kind of combinatorial work, because Integer division is quite expensive. Cheers, Andrew Bromage ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] faster factorial function via FFI?
Dan Weston wrote: A thing of beauty is a joy forever. Simple, fast, elegant. factorial :: Integer - Integer factorial = product . zipWith (^) . factorisedFactorial Well... The zipWith (^) should be map (uncurry (^)). And the performance of this approach is strongly dependent on the efficiency of your prime sieve, so you're moving the complexity around, not eliminating it. The binary splitting method doesn't need a source of primes, and performs half decently on numbers such as fact 1e6 (5.5 million digits computed in about 5 seconds). b ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Newbie seeking advice regarding data structure for a tricky algorithm
Hi, Toby Hutton wrote: Say I want to put the words 'foo', 'bar' and 'baz' into a binary tree. The heuristic requires I split the words into letters and sort them: 'aabbfoorz'. The heuristic then may decide, based on the sorted letters, that 'bar' and 'foo' should go in the left child and 'baz' goes in the right. Typically we'd then simply recurse and for example, the left child's words would be re-sorted into 'abfoor' and the heuristic is reapplied. If we assume that sorting is relatively expensive, we can avoid the re-sort for the children by unmerging the parent's sorted list of letters. Two sublists of a sorted list should already be sorted. If we know which word each letter belongs to it would be more efficient to tag the letters with 'left' or 'right' as the words are classified. Then we can iterate down the sorted letter list and produce new sorted sublists rather simply. So it's not actually that complicated, and I can imagine exactly how it could be done in C but I really don't know how to approach this in Haskell. What about just storing with each character a reference to the word it orignally comes from? import Data.List (sortBy) data Tagged = Tag String Char tag :: Tagged - String tag (Tag x _) = x compareTagged :: Tagged - Tagged - Ordering (Tag _ x) `compareTagged` (Tag _ y) = x `compare` y tagWord :: String - [Tagged] tagWord word = map (Tag word) word unmerge :: [a] - (a - Bool) - ([a], [a]) unmerge xs p = foldr f ([], []) xs where f x (ls, rs) | p x = (x:ls, rs) | otherwise = (ls, x:rs) data Tree = Empty | Leaf String | Node Tree Tree tree :: ([Tagged] - String - Bool) - [String] - Tree tree heuristic words = tree' words sorted where -- we only need to sort once ... sorted = sortBy compareTagged . concat . map tagWord $ words tree' [] _ = Empty tree' [word] _ = Leaf word tree' words sorted = let predicate = heuristic sorted (leftWords, rightWords) = unmerge words predicate -- ... because we reuse the ordered list by unmerging it (leftSorted, rightSorted) = unmerge sorted (predicate . tag) in Node (tree' leftWords leftSorted) (tree' rightWords rightSorted) Tillmann ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Haskell version of Norvig's Python Spelling Corrector
Bryan O'Sullivan wrote: Udo Stenzel wrote: There is another bug of this sort in your code. Consider incWordCount w m = M.insertWith (+) w 1 m There is no reason to evaluate the sum inside the map, instead an unevaluated thunk is put in there. Would not Data.Map.insertWith' do the trick? Oops, you're right, this is a fairly recent addition. -Udo -- Walk softly and carry a BFG-9000. signature.asc Description: Digital signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] HXT namespace problem
runX $ constA (request TableListRequest) root [] [writeA] writeDocument [(a_indent,v_1)] - writeDocument [(a_indent,v_1), (a_check_namespaces, v_1)] - should do the trick. Cheers, Tim ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] About functional programing, type theory and a master thesis topic
Hi everybody =) First time I write to the list. My name is Glauber and I'm doing my master course at UNICAMP, Brazil, under supervisor of Prof. Dr. Arnaldo Vieira Moura. I'm interested in Haskell, type theory and algebraic specification (formal methods). I've been studying these subjects to my Computer-Science-Bachelor-degree-final work. It was an implementation of an homomorphism between a little constructive algebraic specification code (based mainly in Loeckx's Specification of Abstract Data Types) and a Haskell code. SableCC was used as tool to implement the interpreter because I've already used it before. One theme to work one should be implementing this in Haskell itself, but there is already HasCASL. I've already contacted the HasCASL professors and I'm reading more about the project. At the same time, I want to look for some theme under type theory, too. The main concern about HasCASL is that I want to get in deep touch with functional programming during my master thesis and I'm not sure (yet) if studying HasCASL would get me there. I've reading some papers about type theory and Haskell (mainly the ones suggested in the haskell.org site) and as I could see the topics are very interesting. I'm not sure, however, if there is something that can be done in a 2-year-master course. Mainly, they propose new extensions that have became new languages (Cayenne, Omega and Epigram). Other topic I'd like to get in touch is theorem proving. As I could see, Coq and Isabelle are the most used with Haskell. Indeed, HasCASL use Isabelle and this could be a nice thing to work on, as was suggested by HasCASL professors. As I know that lots of you here are researchers, I'd like to ask some opinions about what can be done as a master thesis having in mind that I want to continue in a PhD course after the master one. Sorry if the email is too large. And thank for the patience and for any opinion you can give me. Yours, Glauber. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] About functional programing, type theory and a master thesis topic
On Tue, Apr 24, 2007 at 09:25:55PM -0300, Glauber Cabral wrote: Hi everybody =) First time I write to the list. http://haskell.org/pipermail/haskell-cafe/2007-April/024819.html http://haskell.org/pipermail/haskell-cafe/2007-April/024867.html (I am not a researcher and cannot comment on the rest of your post, except to say that it is not too long.) Stefan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] About functional programing, type theory and a master thesis topic
Hi =) No problem! And sorry by the duplicated post. I've had just checked my gmail and the message was not there, 2 days after posting. I've sent again and then there were 2 copies. Cheers, Glauber On 4/24/07, Stefan O'Rear [EMAIL PROTECTED] wrote: On Tue, Apr 24, 2007 at 09:25:55PM -0300, Glauber Cabral wrote: Hi everybody =) First time I write to the list. http://haskell.org/pipermail/haskell-cafe/2007-April/024819.html http://haskell.org/pipermail/haskell-cafe/2007-April/024867.html (I am not a researcher and cannot comment on the rest of your post, except to say that it is not too long.) Stefan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] About functional programing, type theory and a master thesis topic
On Tue, Apr 24, 2007 at 09:58:01PM -0300, Glauber Cabral wrote: Hi =) No problem! And sorry by the duplicated post. I've had just checked my gmail and the message was not there, 2 days after posting. I've sent again and then there were 2 copies. Cheers, Glauber On 4/24/07, Stefan O'Rear [EMAIL PROTECTED] wrote: On Tue, Apr 24, 2007 at 09:25:55PM -0300, Glauber Cabral wrote: Hi everybody =) First time I write to the list. http://haskell.org/pipermail/haskell-cafe/2007-April/024819.html http://haskell.org/pipermail/haskell-cafe/2007-April/024867.html (I am not a researcher and cannot comment on the rest of your post, except to say that it is not too long.) Stefan gmail is known to randomly eat posts from this list. Stefan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] faster factorial function via FFI?
G'day all. Quoting Bryan O'Sullivan [EMAIL PROTECTED]: Well... The zipWith (^) should be map (uncurry (^)). Err... yes. And the performance of this approach is strongly dependent on the efficiency of your prime sieve, so you're moving the complexity around, not eliminating it. Yes and no. Standard algorithms for computing and manipulating combinatorial-sized Integers strongly depend on the properties of your Integer implementation. Manipulating lists of prime factors can also be more efficient, because most of the numbers you deal with are machine-word-sized. The binary splitting method doesn't need a source of primes, and performs half decently on numbers such as fact 1e6 (5.5 million digits computed in about 5 seconds). And on the other hand, if you're computing something other than just a factorial (e.g. a complex combinatorial function, like the OP said), prime factoring avoids large Integer divisions, which are often many times more expensive than large Integer multiplications. Cheers, Andrew Bromage ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Is Excel a FP language?
In a debate I proposed Excel is a functional language. It was refuted and I'd like to know what some of you clever Haskellers might think :) My opposition proposed (after some weeding out) that there is a distinction between Excel, the application, the GUI and Excel, the language (which we eventually agreed (I think) manifested itself as a .xls file). Similarly, VB is both a language and a development environment and referring to VB is a potential ambiguity. I disagree with this analogy on the grounds that the very definition of Excel (proposed by Microsoft) makes no distinction. Further, it is impossible to draw a boundary around one and not the other. I also pointed to the paper by Simon Peyton-Jones titled, Improving the world's most popular functional language: user-defined functions in Excel, which quite clearly refers to Excel as a [popular] functional language. The debate started when I referred to the fact that financial institutions change their functional language from Excel to something like OCaml or Haskell. Of course, there is no doubting that these companies can replace their entire use of Excel with a functional language, which I think is almost enough to fully support my position (emphasis on almost). -- Tony Morris http://tmorris.net/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] On reflection
Oleg, Simon,
Thanks for your help. If i understand it correctly, the code below gives a
reasonably clean first cut at a demonstration of process calculi as
polymorphically parametric in the type of name, allowing for an
instantiation of the type in which the quoted processes play the role of
name. This is much, much cleaner and easier to read than the OCaml version.
Best wishes,
--greg
{-# OPTIONS -fglasgow-exts -fallow-undecidable-instances #-}
module Core(
Nominal
,Name
,Locality
,Location
,CoreProcessSyntax
,CoreAgentSyntax
,MinimalProcessSyntax
,MinimalAgentSyntax
,ReflectiveProcessSyntax
-- ,make_process
)
where
-- What's in a name?
class Nominal n where
nominate :: i - n i
-- newtype Name i = Nominate i deriving (Eq, Show)
newtype Name i = Name i deriving (Eq, Show)
instance Nominal Name where nominate i = Name i
-- Where are we?
class Locality a where
locate :: (Eq s, Nominal n) = s - (n i) - a s (n i)
name :: (Eq s, Nominal n) = a s (n i) - (n i)
-- data Location s n = Locate s n deriving (Eq, Show)
data Location s n = Location s n deriving (Eq, Show)
instance Locality Location where
locate s n = Location s n
name (Location s n) = n
-- Constraints
class CoreProcessSyntax p a x | p - a x where
zero :: p
sequence :: a - x - p
compose :: [p] - p
class CoreAgentSyntax x p n | x - p n where
bind :: [n] - p - x
offer :: [n] - p - x
-- Freedom (as in freely generated)
data MinimalProcessSyntax l x =
Null
| Sequence l x
| Composition [MinimalProcessSyntax l x]
data MinimalAgentSyntax n p =
Thunk (() - p)
| Abstraction ([n] - p)
| Concretion [n] p
-- Responsibility : constraining freedom to enjoy order
instance CoreProcessSyntax (MinimalProcessSyntax l x) l x where
zero = Null
sequence l a = Sequence l a
compose [] = zero
compose ps = Composition ps
instance CoreAgentSyntax (MinimalAgentSyntax n p) p n where
bind [] proc = Thunk (\() - proc)
-- -- TODO : lgm : need to substitute m for name in proc
bind (name:names) proc = Abstraction (\m - comp $ bind names proc)
where comp (Thunk fp) = fp ()
-- comp (Abstraction abs) = abs name
offer names proc = Concretion names proc
data ReflectiveProcessSyntax =
Reflect
(MinimalProcessSyntax
(Location [(Name ReflectiveProcessSyntax)] (Name
ReflectiveProcessSyntax))
(MinimalAgentSyntax (Name ReflectiveProcessSyntax)
ReflectiveProcessSyntax))
-- instance (CoreProcessSyntax p a x) =
-- CoreProcessSyntax
-- (MinimalProcessSyntax
-- (Location
-- [(Name (MinimalProcessSyntax a x))]
-- (Name (MinimalProcessSyntax a x)))
-- (MinimalAgentSyntax
-- (Name (MinimalProcessSyntax a x))
-- (MinimalProcessSyntax a x)))
-- (Location
-- [(Name (MinimalProcessSyntax a x))]
-- (Name (MinimalProcessSyntax a x)))
-- (MinimalAgentSyntax
-- (Name (MinimalProcessSyntax a x))
-- (MinimalProcessSyntax a x))
--
L.G. Meredith
Managing Partner
Biosimilarity LLC
505 N 72nd St
Seattle, WA 98103
+1 206.650.3740
http://biosimilarity.blogspot.com
___
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Re: [Haskell-cafe] Is there a best *nix or BSD distro for Haskell hacking?
I can confirm that, although before Ubuntu Feisty came out I just compiled GHC 6.6 myself. I was surprised how easy it was -- I had heard building GHC was hard, but I guess that's only if you don't already have a Haskell compiler. I expect I'll probably be compiling the newest version myself again once the features I'm missing out on become important enough to me. --Grady Lemoine On 4/22/07, Ryan Dickie [EMAIL PROTECTED] wrote: I'm running feisty. [EMAIL PROTECTED]:~$ ghc --version The Glorious Glasgow Haskell Compilation System, version 6.6 --ryan On 4/22/07, Dougal Stanton [EMAIL PROTECTED] wrote: On 22/04/07, Ryan Dickie [EMAIL PROTECTED] wrote: Many of the haskell packages including darcs, ghc, and well over 100 other packages (mostly libraries) are in the package manager ready to be installed. The problem with Ubuntu (at least until the Feisty release a few days ago?) was that GHC wasn't up-to-date by default; it came with 6.4. Moving to 6.6 isn't a difficult feat (the generic binaries from the GHC site seem to work fine for Edgy, if you install libreadline too) but being behind that curve is noticeable. If you want to stay on the cutting edge Gentoo takes a lot of the hassle out of it, since you can use the repository stored on haskell.org. The downside is having to keep the rest of the system updated if you've got a slow machine. You pays your money, etc. D. ___ 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 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] faster factorial function via FFI?
[EMAIL PROTECTED] wrote: Yes and no. Standard algorithms for computing and manipulating combinatorial-sized Integers strongly depend on the properties of your Integer implementation. Manipulating lists of prime factors can also be more efficient, because most of the numbers you deal with are machine-word-sized. Yep. By the way, if approximations are good enough, the OP could use Gosper's formula: gosper :: Integral a = a - a gosper n | n 143 = let n' = fromIntegral n g = sqrt ((n' * 2 + 1/3) * pi) * n'**n' * exp (-n') in round g The accuracy of this approximation increases with n, until you hit the ceiling of whatever your Double implementation can manage (142, typically). b ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Is Excel a FP language?
Tony Morris wrote: My opposition proposed (after some weeding out) that there is a distinction between Excel, the application, the GUI and Excel, the language (which we eventually agreed (I think) manifested itself as a .xls file). I say Excel is a functional language. If there needs to be the quoted distinction, fine: Excel the language is a functional language, and Excel the application is an interpreter of said language. (Does the opposition self-consistently distinguish Perl the language from perl.exe the interpreter?) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
