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Announcing initial release of Shaskell, version 0.21a (sha256/sha512 library)
by David Mercer 27 Dec '05

27 Dec '05

We are pleased to announce Version 0.21a, the initial functioning release of Shaskell, our SHA2 library for (so far) ghc6. It supports sha256 and sha512 hashes in this version, and is "pure": no monads or C libraries are involved! Source and Ubuntu 5.04 binaries are at: http://davidmercer.nfshost.com/projects/shaskell/ (Shaskell-0.21a.hs is the current release). Project homepage is at: http://davidmercer.nfshost.com/projects/shaskell/shaskell.html Future releases will additionally support sha224, sha384, be Cabal-ized, and supply wrappers for hashing files and other data sources where the message length is not known in advance. Special thanks to Dominic Steinitz for invaluable suggestions. Any testing or feedback is of course welcome and appreciated! It is released under the (BSD compatible) MIT X license. Happy New Year, hopefully this will help improve the security of future crypto systems written in Haskell. Cheers, -David Mercer Tucson, AZ

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ANN: MissingH 0.13.0
by John Goerzen 26 Dec '05

26 Dec '05

I am pleased to announce the release of MissingH 0.13.0. To download MissingH or view API docs, please visit: http://quux.org/devel/missingh or gopher://quux.org/1/devel/missingh To follow MissingH development with Darcs, please run: darcs get --partial http://darcs.complete.org/missingh 0.13.0 packages have been uploaded to Debian and should appear in sid within a few days. Changes in 0.13.0 since 0.12.3: * This release introduces some API changes that will affect a small percentage of programmers that use ConfigParser. * This release requires GHC 6.4.x or Hugs 2005xx or above. This has been noted in INSTALL. * MissingH.List: Committed some patches from Bulat Ziganshin to improve performance. * New function MissingH.List.subIndex based on suggestion from Bulat Ziganshin. Also added tests for it. * New module MissingH.Map, similar to MissingH.FiniteMap but for Data.Map instead of Data.FiniteMap. Also added tests for MissingH.Map. * New module MissingH.AnyDBM.MapDBM, plus tests for it. Converted from MissingH.AnyDBM.FiniteMapDBM. * Converted these modules to use MVars instead of IORefs: + MissingH.Logging.Logger * Converted these modules to use Data.Map instead of Data.FiniteMap: + MissingH.Logging.Logger + MissingH.MIMETypes + MissingH.ConfigParser (exposes an API change to a few people) * Converted these modules to use Text.Printf instead of MissingH.Printf: + MissingH.IO.HVFS.Utils + MissingH.Network.FTP.Server * Added deprecation warnings to these modules: + MissingH.FiniteMap (deprecation of Data.FiniteMap) + MissingH.AnyDBM.FiniteMapDBM (deprecation of Data.FiniteMap) + MissingH.Printf (introduction of Text.Printf) * Added deprecation warnings for two specific functions in MissingH.Str: subRe and splitRe. I had submitted the code for these to fptools, and the current releases of GHC and Hugs have Text.Regex.subRegex and splitRegex using the code for MissingH. Therefore, these functions in MissingH are deprecated in favor of the implementations in the standard library. * Added locking to StringDBM for thread safety improvements * Merry Christmas! Changes in 0.12.3 since 0.12.2: * Make StreamHandler now lock by default. (requested by Conjure people)

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RE: [Haskell] Boxing (Day) Question
by Nick Benton 26 Dec '05

26 Dec '05

>That reminds me of something that I have wondered about for some >time. Why is there such reluctance to instantiate polymorhic functions >with the types with which they are used? (This isn't done automatically >in complilers right?) MLj, SML.NET and MLton all compile polymorphism this way. They can do it fairly straightforwardly because (a) they have the whole program available, and (b) because SML, unlike Haskell, doesn't have polymorphic recursion. Of course, you don't actually want a copy per source language instantiation type, just a copy per target language representation. The .NET CLR also compiles parametric polymorphism by representation specialization. Thanks to JIT compilation, it can do this lazily, at "run" time, sidestepping both the restrictions above. The details are non-trivial in this context (interfaces, runtime "types", etc.) - see the papers on generics by Andrew Kennedy and Don Syme for the hairy truth. Specialization is (generally) a big performance win over uniform representations for non-symbolic code (e.g. scientific code operating on floats). Nick

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Boxing (Day) Question
by Ashley Yakeley 26 Dec '05

26 Dec '05

As I understand it, with unboxing switched on (->) actually has this kind: (->) :: ? -> ? -> * Reading the Core specification, GHC has a particular kind of "polykindism" which introduces kind "?", and defines specialisation such that "?" may be replaced by "*" or "#" inside any kind. Accordingly, (->) may be specialised: (->) :: * -> * -> * (->) :: # -> * -> * (->) :: * -> # -> * (->) :: # -> # -> * Examples: module Boxing where import GHC.Exts fooSS :: (->) Int Int fooSS 3 = 5 fooSS _ = 2 fooHS :: (->) Int# Int fooHS 3# = 5 fooHS _ = 2 fooSH :: (->) Int Int# fooSH 3 = 5# fooSH _ = 2# fooHH :: (->) Int# Int# fooHH 3# = 5# fooHH _ = 2# type Fun = (->) fooHH' :: Fun Int# Int# fooHH' 3# = 5# fooHH' _ = 2# Do any other type constructors or symbols have a kind with "?" in it? I like the "kind" approach to unboxed types. It automatically rules out "[Int#]" by kind mismatch, for instance. But I was disappointed I couldn't do this with GHC 6.4.1: data MyC s = MkMyC (s Int# Int) or class C s where c :: s Int# Int (in either case: "Kind error: Expecting kind `k_a19o', but `Int#' has kind `#' In the class declaration for `C'") There's no kind mismatch here, merely a restriction that the kinds of arguments to classes be #-free. I can't do this, either: newtype MyD (u :: #) = MkMyD (u -> Bool) GHC actually complains about parsing the kind signature. Would Bad Things Happen if this restriction were lifted? I don't have a pressing need for it actually, though this might be useful: class Boxed (b :: *) (u :: #) | b -> u, u -> b where box :: u -> b unbox :: b -> u In case you're worried, lifting the restriction would NOT allow uncompilable things such as newtype MyE (u :: #) = MkMyE u ...simply because there's already a straightforward restriction that values in type constructors have types of kind "*". It is merely the notion of "#-freeness" that seems unnecessary. It would, however, allow this: newtype Box (u :: #) = MkBox (() -> u) ...and quite possibly this: newtype Value (x :: ?) = MkValue (() -> x) I believe these can be compiled safely? -- Ashley Yakeley, Seattle WA

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Tools for web-based Haskell editing & compilation?
by Conal Elliott 24 Dec '05

24 Dec '05

Has anyone set up GHC to run on a server with modules created, saved, edited, imported, and executed via a web interface? Are there tools existing or under development that support some or all of this scenario? I'm working on a new implementation, "Pajama", of the Pan functional image synthesis DSEL, this time with the compiler targetting Java applets. (The image compiler is implemented in Haskell and generates Java code.) Besides running image effects, I'd also like to allow people to author new effects without having any software installed (GHC, the Pajama compiler, or the Java compiler). For starters, I'm thinking of an editor applet (running in a web page) and a compile server. Ideally, the editor would do syntax coloring and checking, show type annotations, etc, though it doesn't have to do so initially. When a module compiles successfully, the user would select definitions that would get run to generate Java code, which would then be compiled on the server and downloaded to the client via an html applet tag. Thanks, - Conal

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RE: [Haskell] Hlist distribution -- compiler error in TIP
by Ralf Lammel 24 Dec '05

24 Dec '05

Dear Frank, HList is definitely tested with 6.4. See transcript below. My guess would be that you are perhaps not running with options as stated in the Makefile. Anyway, if your problems persist, I am happy to take this offline. Merry Christmas, Ralf ralfla@ralfla02 ~/projects/HList/src $ ghc --version The Glorious Glasgow Haskell Compilation System, version 6.4 ralfla@ralfla02 ~/projects/HList/src $ make test ghci -fglasgow-exts -fallow-overlapping-instances -fallow-undecidable-instances MainGhcGeneric1.hs -v0 < Main.in > MainGhcGeneric1.out diff -b MainGhcGeneric1.out MainGhcGeneric1.ref ghci -fglasgow-exts -fallow-overlapping-instances -fallow-undecidable-instances MainGhcTTypeable.hs -v0 < Main.in > MainGhcTTypeable.out diff -b MainGhcTTypeable.out MainGhcTTypeable.ref runhugs -98 +o MainHugsTTypeable.hs < Main.in > MainHugsTTypeable.out diff -b MainHugsTTypeable.out MainHugsTTypeable.ref ghci -fglasgow-exts -fallow-overlapping-instances -fallow-undecidable-instances MainPosting-040607.hs -v0 < Main.in > MainPosting-040607.out diff -b MainPosting-040607.out MainPosting-040607.ref ghci -fglasgow-exts -fallow-overlapping-instances -fallow-undecidable-instances MainGhcGeneric2.hs -v0 < Main.in > MainGhcGeneric2.out diff -b MainGhcGeneric2.out MainGhcGeneric2.ref ghci -fglasgow-exts -fallow-overlapping-instances -fallow-undecidable-instances MainGhcGeneric3.hs -v0 < Main.in > MainGhcGeneric3.out diff -b MainGhcGeneric3.out MainGhcGeneric3.ref ralfla@ralfla02 ~/projects/HList/src > -----Original Message----- > From: haskell-bounces(a)haskell.org [mailto:haskell-bounces@haskell.org] On > Behalf Of Frank > Sent: Saturday, December 24, 2005 8:46 AM > To: haskell(a)haskell.org > Subject: [Haskell] Hlist distribution -- compiler error in TIP > > I just got the Hlist distribution but could not compile the example files > With ghc 6.4 (I use ghci - in eclipse - I did not use ghc with the > makefile). > > I got the following compile time error on module TIP: > > > C:\gisCodev13\HeterogenousList\src/TIP.hs:247:22: > Could not deduce (HType2HNat e l n1, > HDeleteAtHNat n1 l l'1, > HOccurs e (TIP l), > HOccurs e2 (TIP l'1)) > from the context (HOccurs e1 (TIP l), > HType2HNat e1 l n, > HDeleteAtHNat n l l', > HOccurs e2 (TIP l'), > HOccurs e2 (TIP l), > HType2HNat e2 l n', > HDeleteAtHNat n' l l'', > HOccurs e1 (TIP l'')) > arising from use of `y' at > C:\gisCodev13\HeterogenousList\src/TIP.hs:247:22 > Probable fix: > add (HType2HNat e l n1, > HDeleteAtHNat n1 l l'1, > HOccurs e (TIP l), > HOccurs e2 (TIP l'1)) > to the type signature(s) for `tuple' > or add an instance declaration for (HOccurs e (TIP l), HOccurs e2 > (TIP > l'1)) > In the definition of `tuple': > tuple (TIP l) > = let > x = hOccurs (TIP l) > l' = hDeleteAtProxy (toProxy x) l > y = hOccurs (TIP l') > in (x, y) > > > Can anybody quickly see, what is wrong? > > > > Andrew U. Frank > Professor, Head of Department > Geoinformation and Cartography E127 phone: +43 1 588 01 12710 > TU Vienna secr. +43 1 588 01 12700 > Gusshausstrasse 27-29 fax +43 1 588 01 12799 > A-1040 Vienna Austria cellular phone +43 676 41925 72 > http://www.geoinfo.tuwien.ac.at/persons/frank/frank.html > skype:AndrewUFrank > > _______________________________________________ > Haskell mailing list > Haskell(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell

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Hlist distribution -- compiler error in TIP
by Frank 24 Dec '05

24 Dec '05

I just got the Hlist distribution but could not compile the example files With ghc 6.4 (I use ghci - in eclipse - I did not use ghc with the makefile). I got the following compile time error on module TIP: C:\gisCodev13\HeterogenousList\src/TIP.hs:247:22: Could not deduce (HType2HNat e l n1, HDeleteAtHNat n1 l l'1, HOccurs e (TIP l), HOccurs e2 (TIP l'1)) from the context (HOccurs e1 (TIP l), HType2HNat e1 l n, HDeleteAtHNat n l l', HOccurs e2 (TIP l'), HOccurs e2 (TIP l), HType2HNat e2 l n', HDeleteAtHNat n' l l'', HOccurs e1 (TIP l'')) arising from use of `y' at C:\gisCodev13\HeterogenousList\src/TIP.hs:247:22 Probable fix: add (HType2HNat e l n1, HDeleteAtHNat n1 l l'1, HOccurs e (TIP l), HOccurs e2 (TIP l'1)) to the type signature(s) for `tuple' or add an instance declaration for (HOccurs e (TIP l), HOccurs e2 (TIP l'1)) In the definition of `tuple': tuple (TIP l) = let x = hOccurs (TIP l) l' = hDeleteAtProxy (toProxy x) l y = hOccurs (TIP l') in (x, y) Can anybody quickly see, what is wrong? Andrew U. Frank Professor, Head of Department Geoinformation and Cartography E127 phone: +43 1 588 01 12710 TU Vienna secr. +43 1 588 01 12700 Gusshausstrasse 27-29 fax +43 1 588 01 12799 A-1040 Vienna Austria cellular phone +43 676 41925 72 http://www.geoinfo.tuwien.ac.at/persons/frank/frank.html skype:AndrewUFrank

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ANN: hdbc-postgresql 0.6.0
by John Goerzen 23 Dec '05

23 Dec '05

I am pleased to announce the second database backend driver for HSQL, hdbc-postgresql. This driver obviously supports PostgreSQL databases ;-) Get it with: darcs get --partial --tag=hdbc-postgresql-0.6.0 \ http://darcs.complete.org/hdbc-postgresql -- John Goerzen Author, Foundations of Python Network Programming http://www.amazon.com/exec/obidos/tg/detail/-/1590593715

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Problem with constructing instances for a class Pair
by Frank 23 Dec '05

23 Dec '05

i want the operations on pairs to work for lists applying to each pair in the list. i prefer to achieve this with overloading, using classes and instances i cannot get from the code for the ordinary case: class P a where outl :: a b c -> b ... data P1 p q = P1 p q deriving (Show, Eq, Ord) -- a pair like constructor instance P P1 where outl (P1 p q) = p to code for the mapped case: instance P [P1] where .... gives -- - Kind error: `P1' is not applied to enough type arguments -- - In the instance declaration for `P [P1]' no other combination of parameters i can think of works for an instance of class P for lists. what do i not see? any help appreciated! andrew frank the remainder is the code i have tried: -} module PairTest where class P a where outl :: a b c -> b outr :: a b c -> c make :: b -> c -> a b c data P1 p q = P1 p q deriving (Show, Eq, Ord) type P2 = (,) instance P P2 where outl = fst outr = snd make = (,) instance P P1 where outl (P1 p q) = p outr (P1 p q) = q make = P1 p1list :: [P1 Int Bool] p1list = [P1 3 True, P1 4 False] qlist = fmap outr p1list -- or map --------------can this be done as overloading of outl, outr for lists? outlPl = fmap outl plist = outlPl p1list --instance P [P1] where -- outl = fmap outl -- - Kind error: `P1' is not applied to enough type arguments -- - In the instance declaration for `P [P1]' --instance P [P1 p q] where -- outl = fmap outl -- Kind error: Expecting kind `* -> * -> *', but `[P1 p q]' has kind `*' -- In the instance declaration for `P [P1 p q]' class P3 a b c where outl3 :: a b c -> b --instance P3 [P1 p q] -- - Kind error: Expecting kind `* -> * -> *', but `[P1 p q]' has kind `*' -- - In the instance declaration for `P3 [P1 p q]' Andrew U. Frank Professor, Head of Department Geoinformation and Cartography E127 phone: +43 1 588 01 12710 TU Vienna secr. +43 1 588 01 12700 Gusshausstrasse 27-29 fax +43 1 588 01 12799 A-1040 Vienna Austria cellular phone +43 676 41925 72 http://www.geoinfo.tuwien.ac.at/persons/frank/frank.html skype:AndrewUFrank

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Drawing charts via Haskell
by Gerbrand van Dieijen 23 Dec '05

23 Dec '05

Hello, I plan to develop a library in Haskell to draw charts, such as pie charts, bar charts and line charts, to visualize data. Functionality will be similar to gnuplot, or chart libraries that already exist for other languages. The chart library is for (part of) my master-thesis project and it is still in its planning phase. There are several graphic-libraries for Haskell, but I couldn't find any specifically for drawing charts. To avoid that I am reinventing the wheel, does anyone know of such a library that is already developed or being developed? Regards, -- Gerbrand van Dieijen

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