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ANN: hledger-0.27, with more console power
by Simon Michael 31 Oct '15

31 Oct '15

I'm pleased to announce hledger 0.27! What is it ? hledger is a cross-platform program for tracking money, time, or any other commodity, using double-entry accounting and a simple, editable file format. It can also read CSV or timelog files, and export CSV. It provides command-line, curses and web interfaces, and aims to be a reliable, practical tool for daily use. It is inspired by and largely compatible with ledger(1). What's new ? This release introduces hledger-ui, a new curses-style interface that I'm quite pleased with (not yet available on Windows). Built on vty and the new brick library, it lets you review account balances and transactions with fewer keystrokes and less effort. Ledger users with compatible journal files may also find this useful. hledger can now report current value based on market prices (hurrah); wide characters are displayed properly; regular expression account aliases are fast; and unix man pages are provided. You can see all changes and bugfixes at http://hledger.org/release-notes#hledger-0.27 . Release contributors: Simon Michael, Carlos Lopez-Camey. How to get it ? hledger can be installed with cabal or stack - see http://hledger.org/download for guidance. If you'd like to contribute Windows or Mac binaries, please get in touch. Happy Hallowe'en! -Simon

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Re: [Haskell-cafe] Determining the length of a Foldable Applicative.
by David Banas 31 Oct '15

31 Oct '15

Thanks to all, whom responded to this! With your help, I found my way to this, which seems to work correctly: app_len :: (Foldable f) => f a -> Int app_len = foldl' (flip ((+) . const 1)) 0 -db On Oct 30, 2015, at 2:47 PM, David Kraeutmann <kane(a)kane.cx> wrote: > Your types don't match here, but you have the right idea. > > 'sum' won't be enough. Take a look at the definition of sum: > >> sum :: (Foldable t, Num a) => t a -> a >> sum = getSum . foldMap Sum > > That won't work, since that requires '(Num a)'. > > We just want to count 1 up whenever we map an element. > Try doing something with const and Data.Monoid.Sum. > > > On 10/30/2015 9:03 PM, David Banas wrote: >> Hi all, >> >> I thought I had a simple way to determine the “length" (i.e. - number of elements in) of a Foldable Applicative container: >> >> import Prelude hiding (sum) >> import Data.Foldable (Foldable(..), sum) >> import Control.Applicative >> >> -- Calculate the "length" (i.e. - number of elements in) an Applicative container. >> app_len :: (Applicative f, Foldable f) => f a -> Int >> app_len = sum $ pure 1 >> >> but I didn’t: >> >> app_len_test.hs:9:11: >> Could not deduce (Foldable t0) arising from a use of ‘sum’ >> from the context (Applicative f, Foldable f) >> bound by the type signature for >> app_len :: (Applicative f, Foldable f) => f a -> Int >> at app_len_test.hs:8:12-52 >> The type variable ‘t0’ is ambiguous >> Note: there are several potential instances: >> instance Foldable ((,) a) -- Defined in ‘Data.Foldable’ >> instance GHC.Arr.Ix i => Foldable (GHC.Arr.Array i) >> -- Defined in ‘Data.Foldable’ >> instance Foldable (Const m) -- Defined in ‘Data.Foldable’ >> ...plus four others >> In the expression: sum >> In the expression: sum $ pure 1 >> In an equation for ‘app_len’: app_len = sum $ pure 1 >> >> app_len_test.hs:9:17: >> Could not deduce (Applicative t0) arising from a use of ‘pure’ >> from the context (Applicative f, Foldable f) >> bound by the type signature for >> app_len :: (Applicative f, Foldable f) => f a -> Int >> at app_len_test.hs:8:12-52 >> The type variable ‘t0’ is ambiguous >> Note: there are several potential instances: >> instance Data.Monoid.Monoid a => Applicative ((,) a) >> -- Defined in ‘Control.Applicative’ >> instance Applicative ((->) a) -- Defined in ‘Control.Applicative’ >> instance Control.Arrow.Arrow a => >> Applicative (Control.Arrow.ArrowMonad a) >> -- Defined in ‘Control.Applicative’ >> ...plus 14 others >> In the second argument of ‘($)’, namely ‘pure 1’ >> In the expression: sum $ pure 1 >> In an equation for ‘app_len’: app_len = sum $ pure 1 >> >> Can anyone help me understand what I’m missing? >> >> Thanks, and have a great weekend, >> -db >> >> _______________________________________________ >> Haskell-Cafe mailing list >> Haskell-Cafe(a)haskell.org >> http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe >> >

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Determining the length of a Foldable Applicative.
by David Banas 30 Oct '15

30 Oct '15

Hi all, I thought I had a simple way to determine the “length" (i.e. - number of elements in) of a Foldable Applicative container: import Prelude hiding (sum) import Data.Foldable (Foldable(..), sum) import Control.Applicative -- Calculate the "length" (i.e. - number of elements in) an Applicative container. app_len :: (Applicative f, Foldable f) => f a -> Int app_len = sum $ pure 1 but I didn’t: app_len_test.hs:9:11: Could not deduce (Foldable t0) arising from a use of ‘sum’ from the context (Applicative f, Foldable f) bound by the type signature for app_len :: (Applicative f, Foldable f) => f a -> Int at app_len_test.hs:8:12-52 The type variable ‘t0’ is ambiguous Note: there are several potential instances: instance Foldable ((,) a) -- Defined in ‘Data.Foldable’ instance GHC.Arr.Ix i => Foldable (GHC.Arr.Array i) -- Defined in ‘Data.Foldable’ instance Foldable (Const m) -- Defined in ‘Data.Foldable’ ...plus four others In the expression: sum In the expression: sum $ pure 1 In an equation for ‘app_len’: app_len = sum $ pure 1 app_len_test.hs:9:17: Could not deduce (Applicative t0) arising from a use of ‘pure’ from the context (Applicative f, Foldable f) bound by the type signature for app_len :: (Applicative f, Foldable f) => f a -> Int at app_len_test.hs:8:12-52 The type variable ‘t0’ is ambiguous Note: there are several potential instances: instance Data.Monoid.Monoid a => Applicative ((,) a) -- Defined in ‘Control.Applicative’ instance Applicative ((->) a) -- Defined in ‘Control.Applicative’ instance Control.Arrow.Arrow a => Applicative (Control.Arrow.ArrowMonad a) -- Defined in ‘Control.Applicative’ ...plus 14 others In the second argument of ‘($)’, namely ‘pure 1’ In the expression: sum $ pure 1 In an equation for ‘app_len’: app_len = sum $ pure 1 Can anyone help me understand what I’m missing? Thanks, and have a great weekend, -db

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MonadFix wiki confusion
by Samuel Rødal 30 Oct '15

30 Oct '15

Hello, the MonadFix wiki at https://wiki.haskell.org/MonadFix has a statement that I feel is a bit misleading. In section "2.2 Lazy algorithm interleaved with effects", it claims that making the BTree data structure strict doesn't cause endless recursion. Well, that's true, but that's just because rep_x_sum returns a tuple containing the BTree and the summed values of the current subtree, and the tuple is lazily constructed - postponing the construction of the tree value. So highlighting the fact that the function still works when the BTree structure is made strict is kind of a red herring. Maybe the confusion could be avoided by removing the part about making BTree strict, or adding a note about the tuple still ensuring lazy construction? -- Samuel

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Re: [Haskell-cafe] Find a point inside (x,y,z) -> Bool
by Olaf Klinke 30 Oct '15

30 Oct '15

Martin, this may be impractical performance-wise, but Haskell offers magic data structures for searching. Have a look at Martin Escardo's blog post [1] on infinite search in finite time. There is a package on Hackage [2] implementing it. The `shapes` you get are compact, non-empty subsets of types. If you have a shape shape :: Data.Searchable.Set a then Data.Searchable.search (const True) shape will return some element of your shape. As far as I know nobody has ever used this data structure for solid geometry. You'd need to combine it with some implementation of exact reals [*] to have geometry in a product of closed intervals. A downside is that general intersections don't exist, since the shapes must be non-empty. But since images of searchable sets are searchable, you could define complicated shapes by starting with a simple one and distort it with a function. If your type of space is discrete, then the search function might resort to brute force enumeration if the shape was defined that way. -- Olaf [1] http://math.andrej.com/2008/11/21/a-haskell-monad-for-infinite-search-in-fi… [2] http://hackage.haskell.org/package/infinite-search [*] As far as I am aware there is no appropriate package on Hackage, but Haskell implementations exist in several theses.

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Re: [Haskell-cafe] haskell-ide repository name
by Alan & Kim Zimmerman 30 Oct '15

30 Oct '15

This post generated some discussion on the mailing list(s) [1],[2] and on reddit [3]. The straw poll [4] garnered (as of time of writing this mail) 138 votes, broken down as ghc-ide-engine 56 votes 41% ghc-ide-service 43 votes 31% haskides 19 votes 14% ghc-ide-daemon 16 votes 12% something else 4 votes 3% So it seems -ide-engine is the favourite In a bait-and-switch operation, I think it makes sense to keep the current "haskell-ide" prefix, and so rename it to haskell-ide-engine This has the advantages of a) The prefix is the same, so continuity is slightly better b) It does not mentally shut out any tooling constructed using other compilers/techniques, such as haskell-src-exts If anyone feels strongly that this is wrong, please let me know. Regards Alan [1] https://mail.haskell.org/pipermail/haskell-cafe/2015-October/121965.html [2] https://groups.google.com/forum/#!topic/haskell-ide/hI3MzXbwqTo [3] https://www.reddit.com/r/haskell/comments/3qh19i/rename_haskellide_project/ [4] http://strawpoll.me/5842105/r On Mon, Oct 26, 2015 at 11:06 PM, Alan & Kim Zimmerman <alan.zimm(a)gmail.com> wrote: > At the moment the repository/project is called haskell-ide > > This leads to the impression that it is an IDE. > > It is actually a backend/server to provide services for an IDE > > We are considering changing the name. > > The options are > > haskides / ghc-ide-daemon / ghc-ide-service / ghc-ide-engine > > Please cast your vote at http://strawpoll.me/5842105 > > Thanks > Alan >

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New release Csound-expression 4.9 is out
by Anton Kholomiov 30 Oct '15

30 Oct '15

*The 4.9.0 is out! New features:* csound-expression - Functions for creation of FM-synthesizers. We can create the whole graph of FM-units (with feedback). Check out the module Csound.Air.Fm - Support for Monosynth patches. See atMono in the module Csound.Air.Patch see the function atMono and atMonoSharp. - Easy to use Binaural panning. See the module Csound.Air.Pan It’s like: headPan :: (Sig, Sig) -> Sig -> Sig2headPan (azimuth, elevation) asig = (aleft, aright) the compiler can supply the right extra files by reading the header of .csd - Construction of patches for sound fonts (sfPatch, sfPatchHall). - Table of tables. We can create a table that contains tables. - Harmonic oscillators for subtractive synth: buz and gbuz (the functions are adapted from the Csound ones) - Reverbs for patches. It’s very easy to add a reverb to your patch (withSmallHall patch, withLargeHall patch, etc) - Some bug-fixes csound-catalog - Many mono-synth were added. You can use them with function atMono in place of atMidi. The mono versions of patches have suffix m. Like hammonOrganm or nightPadm. We can use it like this: > dac $ atMono nightPadm - SHARC instruments. SHARC db contains a FFT-samples for sustain notes. It includes many orchestra instruments. There are many new patches that use natural sounding timbres taken from the SHARC library. Check out functions soloSharc, padSharc, dreamSharc. We can use it like this: > dac $ atMidi $ padSharc shCello csound-sampler - Handy function withBpm allows to query current bpm with in the scope of expression. - Sampler mappers were generalized. - Char trigering functions are synchronized with bpm. Cheers! Anton

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2nd CfP: Haskell in Leipzig (Germany) 2015
by Johannes Waldmann 29 Oct '15

29 Oct '15

HaL-10 Haskell in Leipzig (December 4/5) http://nfa.imn.htwk-leipzig.de/HAL2015/ We are proud to present Joachim Breitner (nomeata) as our invited speaker. The submission deadline (November 2) is approaching! See you - Johannes Waldmann (PC chair)

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Re: [Haskell-cafe] GHC can't find DLL dependencies on Windows
by Ryan Scott 29 Oct '15

29 Oct '15

Never mind, I figured it out. Previously, I had been placing C:\msys64\mingw64\bin at the end of my user PATH. It turns out that my PATH was in fact on the DLL search path, but for some reason, an earlier directory on my PATH was causing problems. I can't exactly pinpoint what was causing the problem, but after moving C:\msys64\mingw64\bin to the start of my system PATH, I can run Haskell executables in PowerShell/cmd.exe without a problem. Ryan S.

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Stripe-Haskell Updates !
by David Johnson 29 Oct '15

29 Oct '15

*stripe-haskell 2.0* has been released on hackage. *The 2.0 release will entail the following:* - All types will now live in their own repository 'stripe-core' (for better use w/ ghcjs projects). - 'stripe-http-streams' is a specific http client backend for 'stripe-haskell' - Other backends (wreq, conduit, etc.) can be added. As always, pull requests welcome. - 'stripe-haskell' is now a virtual package that wraps 'stripe-http-streams' and 'stripe-core'. - We have a 'gitter' chat for our repo, to promote collaboration. - We now have a multi-ghc travis build that uses stack. - Jeremy Shaw has implemented a novel approach to the optional parameters problem using typeclasses. The docs will contain more information. - For existing stripe-haskell users version 2.0 is a breaking change, but it features a nicer interface due to Jeremy Shaw's changes. *Other notes:* - Existing 1.4 users will not be neglected. We can continue to submit patches up to 2.0. *Future goals:* - Migrate to servant-client ASAP. - Continue to beg Stripe for a machine readable specification that will relieve us from having to perform manual updates on subsequent API changes, and furthermore will allow us to fully take advantage of this wonderful service. Please respond here if you have questions, or visit our gitter at https://gitter.im/dmjio/stripe.

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