- Haskell-Cafe - Haskell.org

Where is SNMap for stable names?
by Sean Leather 24 Sep '11

24 Sep '11

There is an abstract type called SNMap for stable names referred to in [1]. This has apparently disappeared from GHC a long time ago. Is it still available somewhere, or is there a suitable replacement for it? Regards, Sean [1] "Stretching the storage manager: weak pointers and stable names in Haskell" - http://research.microsoft.com/apps/pubs/default.aspx?id=67497

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ANN: flexiwrap-0.1.0 etc.
by Iain Alexander 24 Sep '11

24 Sep '11

New versions of the package flexiwrap (supplying flexible wrappers for instance selection) and related packages have been released to Hackage. flexiwrap-0.1.0 data-type-0.1.0 function-combine-0.1.0 flexiwrap-smallcheck-0.0.1 flexiwrap version 0.1.0 supports instances of many additional classes for FlexiWrap, and improved documentation, although much remains to be done - more class instances for FlexiWrap, and other wrappers, and more documentation. data-type version 0.1.0 adds a proxy type Data.Type.Proxy. function-combine version 0.1.0 updates its dependencies to support the new version of data-type. flexiwrap-smallcheck version 0.1.0 is a new package supplying support for instances of Serial for FlexiWrap, for use with the smallcheck package. Support for Serial instances for other wrappers is outstanding. Regards, Iain. -- ia(a)stryx.demon.co.uk

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Standard 'decorator' class?
by Jacques Carette 23 Sep '11

23 Sep '11

Has a class like class Decoration t where type Datum t :: * value :: t -> Datum t been defined in any of the haskell packages on hackage? [There are so many variants on naming, it is rather difficult to search for this] Jacques

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Re: [Haskell-cafe] Fwd: problem with cabal install MissingH-1.1.1.0
by Tom Murphy 23 Sep '11

23 Sep '11

I used to have a lot of cabal problems when running a version of the GHC installed with MacPorts. I notice you're using homebrew. Maybe that's part of the problem? Tom On Sep 22, 2011 8:11 PM, "Mariano Cortesi" <mcortesi(a)gmail.com> wrote:

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[ANNOUNCE] skein-0.1: Skein, a family of cryptographic hash functions. Includes Skein-MAC as well.
by Felipe Almeida Lessa 23 Sep '11

23 Sep '11

Hello! I'm pleased to announce the first version of the skein package [1]! Skein is a family of fast secure cryptographic hash functions [2]. The skein package provides high-level bindings (using crypto-api [3]) to the optimized Skein C library. Currently we support Skein as a hash function and also Skein as a message authentication code (MAC). The code is well-documented with examples and has many known answer tests (KATs). It currently lives on patch-tag [4]. Hackage will be build the docs soon enough. Meanwhile, here's a short example: Prelude> :s -XOverloadedStrings Prelude> :m Crypto.Skein Crypto.Classes Data.ByteString.Char8 Data.Serialize Prelude Crypto.Skein Crypto.Classes Data.ByteString.Char8 Data.Serialize> encode (hash' "Haskell" :: Skein_512_512) "b\227\213t\170\GS\131w\151\240\160\183\205\US\169\138\&6\239\215\156\227\SI\234\142P\132\182\SOH\180t\203b\147\190\DLE{\168\214\DC1\238\232y\168\161s\207\172\216\a\202\130c$\SYN\asD<\151\201D\138A\SUB" Prelude Crypto.Skein Crypto.Classes Data.ByteString.Char8 Data.Serialize> encode (skeinMAC' "secretkey" "Haskell" :: Skein_512_512) "_i>.Z\129\ENQ\217L\t9BZ\220\163c&9#\135\234A{\181\&2*\149\STX\216_\DC43\bF\189\196D\r ;\208\EOT}\ENQY\147\232\244e/;4\212!\224\US\138\138\234q=1\129\244" Enjoy! =D [1] http://hackage.haskell.org/package/skein [2] http://swww.skein-hash.info/ [3] http://hackage.haskell.org/package/crypto-api [4] https://patch-tag.com/r/felipe/skein/ -- Felipe.

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Package versioning policy - Harmless type changes?
by Heinrich Apfelmus 23 Sep '11

23 Sep '11

Dear all, the package versioning policy specifies that changing the type of any entity makes a change of the B number in A.B.C necessary. However, it seems to me that a small selection of type changes don't break dependent code. In particular, consider the following example, where I drop a Typeable class constraint: - foo :: Typeable a => AddHandler a -> NetworkDescription (Event a) + foo :: AddHandler a -> NetworkDescription (Event a) Can removing a type class constraint on a function break dependent code? Should I change the B number or just the C in version A.B.C when introducing this change? Best regards, Heinrich Apfelmus -- http://apfelmus.nfshost.com

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regex-applicative library needs your help! (algorithmic challenge)
by Roman Cheplyaka 23 Sep '11

23 Sep '11

Please help make the regex-based parsing library efficient! https://github.com/feuerbach/regex-applicative/wiki/Call-For-Help -- Roman I. Cheplyaka :: http://ro-che.info/

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Quick check finite data generation
by mukesh tiwari 23 Sep '11

23 Sep '11

Hello all I have a data type data Index = Index {indexSize::Float, indexIds::[Int], indexDown::(IntMap.IntMap Index)} | IndexLeaf {indexSize::Float, indexIds::[Int]} | IndexEmpty {indexSize::Float} deriving ( Show , Eq ) I derived some thing like this for QuickCheck testing instance Arbitrary a => Arbitrary ( IntMap a ) where arbitrary = liftM IntMap.fromList arbitrary instance Arbitrary Index where arbitrary = oneof [ liftM3 Index arbitrary arbitrary arbitrary , liftM2 IndexLeaf arbitrary arbitrary , liftM IndexEmpty arbitrary ] but its generating infinite list of data. After reading the paper QuickCheck: A Lightweight Tool for Random Testing of Haskell Programs<http://www.eecs.northwestern.edu/%7Erobby/courses/395-495-2009-fall/quick.p…> <http://www.eecs.northwestern.edu/%7Erobby/courses/395-495-2009-fall/quick.p…> i tried to write above one using sized but i am not sure how to write this . instance Arbitrary a => Arbitrary ( IntMap a ) where arbitrary = liftM IntMap.fromList arbitrary instance Arbitrary Index where arbitrary = sized arbIndex arbIndex 0 = liftM IndexEmpty arbitrary arbIndex 1 = liftM2 IndexLeaf arbitrary arbitrary arbIndex n = frequency [ ( 1 , liftM IndexEmpty arbitrary ) , ( 1 , liftM2 IndexLeaf arbitrary arbitrary ) , ( 2 , liftM2 Index arbitrary arbitrary ( arbIndex $ div n 2 ) ) ] but from this type i can see arbIndex $ div n 2 will return Gen Index not Gen ( IntMap Index ) and i am getting compiler error . Could some one please tell me , how to write arbIndex n in terms of smaller n like in the paper arbTree 0 = liftM Leaf arbitrary arbTree n = frequency[ ( 1 , liftM Leaf arbitrary ) , ( 4 , liftM2 Branch ( arbTree $ div n 2 ) ( arbTree $ div n 2 ) ) ] Thank You Mukesh Tiwari

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ANN: New releases in the lightweight monadic regions family
by Bas van Dijk 23 Sep '11

23 Sep '11

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problem with cabal install MissingH-1.1.1.0
by Mariano Cortesi 23 Sep '11

23 Sep '11

Hi, My name is mariano and I'm quite new to haskell. I trying to setup up my environment and use the eclipse plugin for haskell. But is not working property because, it tries to compile the scion browser and this depends on MissingH which fails on build. I'm with mac OS X lion, ghc version 7.2.1 and when a i try to install MissingH version 1.1.1.0 it fails with [24 of 47] Compiling Data.BinPacking ( src/Data/BinPacking.hs, dist/build/Data/BinPacking.o ) src/Data/BinPacking.hs:45:6: Illegal datatype context (use -XDatatypeContexts): (Num size, Ord size, Show size, Show obj) => cabal: Error: some packages failed to install: MissingH-1.1.1.0 failed during the building phase. The exception was: ExitFailure 1 Any ideas? I don't know what to do :S best, Mariano

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