- Haskell-Cafe - Haskell.org

process package with compilers besides GHC
by Michael Snoyman 03 Nov '15

03 Nov '15

I'm currently in the process* of a cleanup of the process package to reduce the usage of CPP conditionals in the code. Currently, as Simon PJ pointed out, it's quite difficult to follow the logic between Windows and POSIX platforms. During the cleanup, I've noticed that: 1. There's also quite a bit of complication around the __GLASGOW_HASKELL__ conditionals, intended to make the package compilable with other compilers 2. There seems to be no way that - in its current state - the package could be compilable with a compiler besides GHC I wanted to reach out and see if anyone is currently using the process package on a compiler besides GHC, and if so, get information on whether recent releases also work, and get some kind of automated testing in place to prevent regressions. If there are no such users, I'm likely to remove the (presumably non-working) conditionals. * No pun intend

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ANN: dimensional-1.0 for statically checked physical dimensions
by Douglas McClean 02 Nov '15

02 Nov '15

Hello Haskellers, Björn Buckwalter and I are pleased to announce the release to Hackage of version 1.0 of the dimensional library, which statically tracks physical dimensions in Haskell code, as in the example below, preventing dimensional mistakes and requiring explicit documentation of units where raw values are exchanged with external systems. {-# LANGUAGE NoImplicitPrelude #-} module Example where import Numeric.Units.Dimensional.Prelude import Numeric.Units.Dimensional.NonSI -- a function that computes with dimensional values escapeVelocity :: (Floating a) => Mass a -> Length a -> Velocity a escapeVelocity m r = sqrt (two * g * m / r) where two = 2 *~ one g = 6.6720e-11 *~ (newton * meter ^ pos2 / kilo gram ^ pos2) >>> let re = 6372.792 *~ kilo meter >>> let me = 5.9742e24 *~ kilo gram >>> let ve = escapeVelocity me re >>> ve -- Show defaults to SI base units 11184.537332296259 m s^-1 >>> showIn (mile / hour) ve -- but we can show in other units "25019.09746845083 mi / h" >>> let vekph = ve /~ (kilo meter / hour) -- and extract raw values when needed 40264.33439626653 This version is a major upgrade, consolidating features from the classic dimensional package and the dimensional-tf package. It takes advantage of the DataKinds and ClosedTypeFamilies extensions in GHC 7.8 to offer even safer types with a nearly identical interface. Also included: - Units carry names which can be combined by multiplication, division, and (only where appropriate) application of metric prefixes. You can use expressions like: showIn (milli meter / second) timeTravelSpeed to get "39339.52 mm / s" - Exact conversion factors between units are available, even when those conversion factors involve multiples of pi, thanks to the exact-pi library - The dimensionally-polymorphic siUnit term represents the coherent SI base unit of any dimension, which can be convenient for wrapping and unwrapping quantities in some contexts. - Storable and Unbox instances for Quantity types are available thanks to the efforts of Alberto Valverde González. - The Numeric.Units.Dimensional.Dynamic module offers types for safely manipulating quantities and units whose dimensions are not known statically. Also available is a term-level representation for dimensions. - Several other missing instances have been provided, including Bounded, Data, and Typeable instances. - New commonly used US customary units have been added, including US fluid measures and the knot. We have several other development efforts underway, including a type-checker plugin inspired by Adam Gundry's work, and on which he has provided valuable advice, which we hope will lead to a clean library for dimensionally typed linear algebra. Comments and contributions are welcome at http://github.com/bjornbm/dimensional-dk. (The repository name is a carryover from the name we were using while developing this version.) One particularly welcome contribution would be assistance with developing a patch for GHC issue 10391 <https://ghc.haskell.org/trac/ghc/ticket/10391>. Cheers, Doug McClean

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Why does disambiguation in RebindableSyntax sometimes requires type signatures?
by Jan Bracker 02 Nov '15

02 Nov '15

Hello, I am currently playing around with RebindableSyntax and having several bind/return/sequence functions in scope at the same time. I thought that it would be enough to just pick the right one to use in each do-block by using a "where" or a "let". Surprisingly, I get some type related issues I can only fix by adding in some type signatures, but I don't understand why these signatures are actually necessary. Here is my example program: {-# LANGUAGE RebindableSyntax #-} {-# LANGUAGE DataKinds #-} {-# LANGUAGE TypeOperators #-} import Prelude import qualified Prelude as P import qualified Control.Effect as E import Control.Effect.State ifThenElse :: Bool -> a -> a -> a ifThenElse True t e = t ifThenElse False t e = e main :: IO () main = do return () where return = P.return data Tree = Leaf Int | Branch Tree Tree process :: Tree -> State '[ "flatten" :-> Bool :! 'R ] (Either Tree [Int]) process (Leaf i) = do flatten <- get (Var :: (Var "flatten")) if flatten then return $ Right [i] else return $ Left $ Leaf i where --(>>=) :: (E.Inv State f g) => State f a -> (a -> State g b) -> State (E.Plus State f g) b (>>=) = (E.>>=) (>>) :: (E.Inv State f g) => State f a -> State g b -> State (E.Plus State f g) b (>>) = (E.>>) return = E.return fail = E.fail process (Branch tl tr) = do eitherL <- process tl eitherR <- process tr case (eitherL, eitherR) of (Left l, Left r) -> return $ Left $ Branch l r (Right l, Right r) -> return $ Right $ l ++ r where (>>=) :: (E.Inv State f g) => State f a -> (a -> State g b) -> State (E.Plus State f g) b (>>=) = (E.>>=) (>>) :: (E.Inv State f g) => State f a -> State g b -> State (E.Plus State f g) b (>>) = (E.>>) return = E.return fail = E.fail The program uses the "effect-monad" package in version 0.6.1. 1) The type signatures in the "where" following each do-block of the "process" function are required. If I remove the type signature of the sequence functions I get a type error of the following nature: examples/effect/Test.hs:33:16: Could not deduce (E.Inv m0 f0 g0) arising from a use of ‘E.>>’ Relevant bindings include (>>) :: m0 f0 a -> m0 g0 b -> m0 (E.Plus m0 f0 g0) b (bound at examples/effect/Test.hs:33:9) In the expression: (E.>>) In an equation for ‘>>’: (>>) = (E.>>) In an equation for ‘process’: process (Leaf i) = do { flatten <- get (Var :: Var "flatten"); if flatten then return $ Right [...] else return $ Left $ Leaf i } where (>>=) = (E.>>=) (>>) = (E.>>) return = E.return fail = E.fail examples/effect/Test.hs:33:16: No instance for (E.Effect m0) arising from a use of ‘E.>>’ In the expression: (E.>>) In an equation for ‘>>’: (>>) = (E.>>) In an equation for ‘process’: process (Leaf i) = do { flatten <- get (Var :: Var "flatten"); if flatten then return $ Right [...] else return $ Left $ Leaf i } where (>>=) = (E.>>=) (>>) = (E.>>) return = E.return fail = E.fail Which I interpret as the inability to infer the "E.Effect" and "E.Inv" constraints that are implied by the use of "E.>>". But why can't those constraints be inferred correctly? Shouldn't a definition like "(>>) = (E.>>)" just propagate the type signature and specialize it as needed? 2) If I remove the type signature for the bind operation, I get the following type error: examples/effect/Test.hs:38:3: Couldn't match type ‘'["flatten" :-> (Bool :! 'R)]’ with ‘'[]’ Expected type: State '["flatten" :-> (Bool :! 'R)] (Either Tree [Int]) -> (Either Tree [Int] -> State '[] (Either Tree [Int])) -> State '[] (Either Tree [Int]) Actual type: State '["flatten" :-> (Bool :! 'R)] (Either Tree [Int]) -> (Either Tree [Int] -> State '[] (Either Tree [Int])) -> State (E.Plus State '["flatten" :-> (Bool :! 'R)] '[]) (Either Tree [Int]) In a stmt of a 'do' block: eitherR <- process tr In the expression: do { eitherL <- process tl; eitherR <- process tr; case (eitherL, eitherR) of { (Left l, Left r) -> return $ Left $ Branch l r (Right l, Right r) -> return $ Right $ l ++ r } } In an equation for ‘process’: process (Branch tl tr) = do { eitherL <- process tl; eitherR <- process tr; case (eitherL, eitherR) of { (Left l, Left r) -> return $ Left $ Branch l r (Right l, Right r) -> return $ Right $ l ++ r } } where (>>=) = (E.>>=) (>>) :: (E.Inv State f g) => State f a -> State g b -> State (E.Plus State f g) b (>>) = (E.>>) return = E.return Which tells me that GHC is expecting the wrong type, but inferring the correct type. Again I don't see why this wrong type is expected and the right type is ignored. In either case, why does adding or removing the type signature for the local definitions make a difference at all? I suspect the issue has to do with the language extensions I enabled or the type-level computations that are done by the "effect-monad" package, but I cannot find a satisfying answer. Does anybody have a good explanation? I am working with GHC 7.10.2. Best, Jan

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simple library for HTML form generation and processing
by Henning Thielemann 02 Nov '15

02 Nov '15

I posted the following already to web-devel(a)haskell.org but it seems to be relatively quiet there. ----- I like to get your advice about a simple library for web form generation and processing. So far I tried digestive-functors and reform. Both of them are advertised as being good in separating data from view. However, I am interested in one-off forms, that is, form data will always be rendered in one way. Thus I would like to save the efforts to combine data and view after they have been carefully separated. Formerly I have also used autolib-cgi: http://autolat.imn.htwk-leipzig.de/haddock/autolib-cgi-1.2/ It allowed me to generate the form and fetch and validate the data in one (monadic) go. The blaze-markup type MarkupM is a monad anyway, thus it seems to be straight-forward to use the monadic results for the data entered to the form. Is there a library that supports this style of web form handling?

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testing for exceptions
by Roelof Wobben 02 Nov '15

02 Nov '15

Hello, I have made this exercise which can be found at the Craft of Functional Programming book. -- exercise 32 -- Suppose we have to raise 2 to the power n. If n is even, 2*m say, then -- 2n = 22*m = (2m)2 -- If n is odd, 2*m+l say, then -- 2n = 22*m+l = (2n)2*2 -- Give a recursive function to compute 2n which uses these insights. f2 :: Integer -> Integer f2 n | n < 0 = error "This will only run for positive numbers" | n == 0 = 1 | even n = f2 ( n `div` 2) ^ 2 | odd n = (f2 ( n `div` 2) ^ 2) * 2 Now I have to make Hunit tests for it, But is there a way I can test if the error message is shown when a negative number is being used ? Roelof

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what do I have to do exactlry with this exercises
by Roelof Wobben 02 Nov '15

02 Nov '15

Hello, Im self studing Haskell with the Craft o ffunctional programmimg of Hutton. Now I see two exercises that I do not understand what is really the purpose here. The two exercises are : 4.21 Given a function f of type Integer -> Integer give a recursive definition of a function of type Integer -> Integer which on input n returns the maximum of the values f 0, f 1, ..., f n. You might find the max function defined in Section 3.4 useful. To test this function, add to your script a definition of some values of f thus: f 0 = 0 f 1 = 44 f 2 = 17 f _ = 0 and so on; then test your function at various values. 4.22 Given a function f of type Integer -> Integer give a recursive definition of a function of type Integer -> Bool which on input n returns True if one or more of the values f 0, f 1, ..., f n is zero and False otherwise.

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Find a point inside (x,y,z) -> Bool
by martin 02 Nov '15

02 Nov '15

Hello all, I hope this is not a too silly question. It goes like this: Suppose I have a shape defined as (x,y,z) -> Bool how can I find a Point inside this shape? Obviously I could iterate through all possible x,y and z, but this appears very expensive. There may be no point at all at x=0. With brute force iteration I would have no clue that the False I am receiving with (0,1,1) is caused by x=0 and I may nedlessly try all combinations of y and z without ever receiving a True. Are there any alternative ways of finding points inside a shape?

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Re: [Haskell-cafe] ANN: hledger-0.27, with more console power
by Simon Michael 01 Nov '15

01 Nov '15

Hi Johannes, quite right. I've added a few screenshots to the manual at http://hledger.org/manual#ui <http://hledger.org/manual#ui> . Some of them use the more realistic example data from the beancount project, thanks to Martin Blais. Best, -Simon > On Nov 1, 2015, at 10:16 AM, johannesjh(a)gmail.com wrote: > > Hi Simon! > > The availability of a text-based user interface for hledger sounds great. Could you please post some screenshots of what the UI looks like? > > thank you very much, > Johannes > > > > On Saturday, October 31, 2015 at 10:38:20 PM UTC+1, Simon Michael (sm) wrote: > 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 <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 <http://hledger.org/download> for guidance. > If you'd like to contribute Windows or Mac binaries, please get in > touch. > > Happy Hallowe'en! > -Simon > > > -- > You received this message because you are subscribed to the Google Groups "hledger" group. > To unsubscribe from this group and stop receiving emails from it, send an email to hledger%2Bunsubscribe(a)googlegroups.com <mailto:hledger+unsubscribe@googlegroups.com>. > For more options, visit https://groups.google.com/d/optout <https://groups.google.com/d/optout>.

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Month in Haskell Mode October 2015
by Gracjan Polak 01 Nov '15

01 Nov '15

Welcome Haskell Mode users, Haskell Mode progress report for October 2015. It is also available online <https://github.com/haskell/haskell-mode/wiki/Month-in-Haskell-Mode-October-…> and on reddit <https://www.reddit.com/r/haskell/comments/3r26px/month_in_haskell_mode_octo…> . For previous issue see September 2015 <https://github.com/haskell/haskell-mode/wiki/Month-in-Haskell-Mode-Septembe…> . <https://github.com/haskell/haskell-mode/wiki/Month-in-Haskell-Mode-October-…>What is Haskell Mode? Haskell Mode is an umbrella project for multiple Emacs tools for efficient Haskell development. Haskell Mode is an open source project developed by a group of volunteers. For more information see https://github.com/haskell/haskell-mode. <https://github.com/haskell/haskell-mode/wiki/Month-in-Haskell-Mode-October-…>Important developments Functionality provided by haskell-indentation received a lot of fixes and contributions lifting it to a complete new level of quality. haskell-indentation is now a default indentation mode enabled when haskell-mode itself is enabled. ATTENTION TUTORIAL WRITERS: The following line is NO LONGER NEEDED: (add-hook 'haskell-mode-hook 'haskell-indentation-mode) PLEASE REMOVE IT FROM ALL THE TUTORIALS OUT THERE. Thanks. Note that for backward compatibility all other indentation modes know how to properly handle new defaults. We have also improved our development process by defining Complete functionality <https://github.com/haskell/haskell-mode/wiki/Complete-functionality> as a concept. <https://github.com/haskell/haskell-mode/wiki/Month-in-Haskell-Mode-October-…>Cooperation with related projects As noted last time Haskell Mode wanted to reach out to other projects in editor space. This has not happened because even better events unfolded. Things of note: haskell-ide-(backend) <https://github.com/haskell/haskell-ide> project got started by Alan Zimmerman. The goal is to bring in all the backend tools that editors need to properly handle advanced Haskell editing. ghc-mod <https://github.com/kazu-yamamoto/ghc-mod> does not need to be introduced. We are thinking how to better split work between haskell-mode and ghc-mod. HaRe <https://github.com/RefactoringTools/HaRe> is a Haskell refactorer. It can rename all the one letter variables to something more descriptive! It can also do other things. And it has somewhat working Emacs integration. <https://github.com/haskell/haskell-mode/wiki/Month-in-Haskell-Mode-October-…>Heads up tutorial writers! There are plenty tutorials out there how to setup haskell-mode. Thanks for writing those! Note that some of them are quite outdated at this point in time and a bit confusing due to the improvements in haskell-mode. Can I ask tutorial writers to contribute directly to haskell mode documentation so that Haskell Mode Manual can be kept up to date with haskell-mode developments? Please contribute documentation back to the project. External tutorials get out of hand pretty fast. Thanks <https://github.com/haskell/haskell-mode/wiki/Month-in-Haskell-Mode-October-…>Heads up! Cruft removal! haskell-mode is about to loose some weight so that it can be better carried by Haskell Mode Community. On the list to be removed are: - Remove haskell-bot.el <https://github.com/haskell/haskell-mode/pull/960> - Remove scc functions <https://github.com/haskell/haskell-mode/pull/961> - Remove horizontal whitespace based smart indentation mode haskell-simple-indent <https://github.com/haskell/haskell-mode/pull/958> - Remove Unicode input method <https://github.com/haskell/haskell-mode/pull/939> - Remove haskell-checkers.el <https://github.com/haskell/haskell-mode/pull/959> If you use one of the above yourself, feel strongly that it should be supported by the community and volunteer to write some unit tests and documentation, please speak up! The changes above will be merged no earlier than December 2015 so there is time to chime in. <https://github.com/haskell/haskell-mode/wiki/Month-in-Haskell-Mode-October-…>Current project focus Current project focus is to lower entry barrier for newcomers by defining bite-sized tasks. Get 50 'well-defined-tasks' done as by the metric: https://github.com/haskell/haskell-mode/issues?q=is%3Aissue+label%3Awell-de… A 'well-defined-task' is a category of tasks that have the field cleared for them, questions already sorted out and detailed information how to get them done. So you can just sit, search for 'well-defined-task' label and enjoy the coding! The point is to lower the entry barrier for new users, new issue reporters and advanced programmers but Emacs lisp beginners to contribute to the project. Current status: 13 well-defined-tasks closed <https://github.com/haskell/haskell-mode/issues?q=is%3Aissue+label%3Awell-de…> plus 13 more open <https://github.com/haskell/haskell-mode/issues?q=is%3Aissue+label%3Awell-de…> . If only you can help with reaching our targets please do so! <https://github.com/haskell/haskell-mode/wiki/Month-in-Haskell-Mode-October-…>Issues closed in October - Disable Indentation #90 <https://github.com/haskell/haskell-mode/issues/90> - Unicode symbols inside ghci prompt hang inferior-haskell-mode #176 <https://github.com/haskell/haskell-mode/issues/176> - Multi-line -ferror-spans syntax not supported #192 <https://github.com/haskell/haskell-mode/issues/192> - [Discussion] Add end-to-end guide for configuring haskell-mode in a place where users will see it #197 <https://github.com/haskell/haskell-mode/issues/197> - Sorting imported functions from a module alphabetically #206 <https://github.com/haskell/haskell-mode/issues/206> - After the newline have to hit twice to start cycling #276 <https://github.com/haskell/haskell-mode/issues/276> - indent-according-to-mode opens the help buffer for haskell-mode-hook #290 <https://github.com/haskell/haskell-mode/issues/290> - Can't get type info unless file compiles #294 <https://github.com/haskell/haskell-mode/issues/294> - Parsing broken on quasi quotes #323 <https://github.com/haskell/haskell-mode/issues/323> - getLine behaves not correctly in Interactive-Haskell-mode. #333 <https://github.com/haskell/haskell-mode/issues/333> - Overly aggressive indenting after recent Emacs update #377 <https://github.com/haskell/haskell-mode/issues/377> - haskell-indentation-mode parse error on indenting import declaration #397 <https://github.com/haskell/haskell-mode/issues/397> - Pick one indentation mode as preferred in the documentation/customize. #414 <https://github.com/haskell/haskell-mode/issues/414> - haskell-indendation and guards #481 <https://github.com/haskell/haskell-mode/issues/481> - Running indent-according-to-mode moves the cursor way to the right #488 <https://github.com/haskell/haskell-mode/issues/488> - haskell-session-change-target should list available targets #534 <https://github.com/haskell/haskell-mode/issues/534> - Haskell-mode crashing and buffer erased (not sure exactly where problem is) #594 <https://github.com/haskell/haskell-mode/issues/594> - haskell-indentation breaks with UnicodeSyntax #715 <https://github.com/haskell/haskell-mode/issues/715> - Handle Template Haskell / DataKinds names in haskell-indentation #760 <https://github.com/haskell/haskell-mode/issues/760> - No indentation suggested for case clauses #786 <https://github.com/haskell/haskell-mode/issues/786> - Pull in ghc-mod's ghc-make-indent-shallower/deeper into haskell-mode #826 <https://github.com/haskell/haskell-mode/issues/826> - Clean up example init.el on wiki #843 <https://github.com/haskell/haskell-mode/issues/843> - Indentation mode needs to be able to recover from parser errors #861 <https://github.com/haskell/haskell-mode/issues/861> - haskell-simple-indent-mode non-responsive #867 <https://github.com/haskell/haskell-mode/issues/867> - Get hit by 'Invalid Token := )' #875 <https://github.com/haskell/haskell-mode/issues/875> - Invalid Token :| #878 <https://github.com/haskell/haskell-mode/issues/878> - Parse error: Illegal token: where #883 <https://github.com/haskell/haskell-mode/issues/883> - parse-error "Expecting then" "Expecting else" DoAndIfThenElse in indentation #884 <https://github.com/haskell/haskell-mode/issues/884> - Illegal tokens and QuasiQuotes #894 <https://github.com/haskell/haskell-mode/issues/894> - Haskell Interactive Shell Stuck in Insert Mode (spacemacs) #895 <https://github.com/haskell/haskell-mode/issues/895> - Syntax highlighting: no difference between data constructor and type ? #898 <https://github.com/haskell/haskell-mode/issues/898> - Let the enter create a new line despite the indentation errors #905 <https://github.com/haskell/haskell-mode/issues/905> - Parse Error inside QuasiQuotes #907 <https://github.com/haskell/haskell-mode/issues/907> - "Expecting else" error message #917 <https://github.com/haskell/haskell-mode/issues/917> - Support commas in first indentation column #918 <https://github.com/haskell/haskell-mode/issues/918> - haskell-process changes the directory which causes loaded modules to be unloaded #923 <https://github.com/haskell/haskell-mode/issues/923> - Syntax highlighting only #924 <https://github.com/haskell/haskell-mode/issues/924> - haskell-process.el binds C-c c but should not #926 <https://github.com/haskell/haskell-mode/issues/926> - Simple indent vs haskell-indentation when using autofill on comments #932 <https://github.com/haskell/haskell-mode/issues/932> - How to use REPL with stack? #953 <https://github.com/haskell/haskell-mode/issues/953> - Wiki documentation out of sync ? #968 <https://github.com/haskell/haskell-mode/issues/968> ### Pull requests merged in October - Support where keyword after any expression #897 <https://github.com/haskell/haskell-mode/pull/897> - Support names starting with quotes #903 <https://github.com/haskell/haskell-mode/pull/903> - Fix switching to the presentation buffer #904 <https://github.com/haskell/haskell-mode/pull/904> - Implement QuasiQuotes syntax in indentation #909 <https://github.com/haskell/haskell-mode/pull/909> - Add build notification to #haskell-emacs #912 <https://github.com/haskell/haskell-mode/pull/912> - Mobile friendly README.md #913 <https://github.com/haskell/haskell-mode/pull/913> - Add failing tests for indentation #916 <https://github.com/haskell/haskell-mode/pull/916> - Toplevel indentation bugfixes for data, newtype, instance #919 <https://github.com/haskell/haskell-mode/pull/919> - Document failing indentation #920 <https://github.com/haskell/haskell-mode/pull/920> - Navigate to top level declaration in indenatation #921 <https://github.com/haskell/haskell-mode/pull/921> - Make haskell indentation the default indentation mode #922 <https://github.com/haskell/haskell-mode/pull/922> - Don't change directory when using stack-ghci. #925 <https://github.com/haskell/haskell-mode/pull/925> - Add rather baroque indentation test which cause parse failure #927 <https://github.com/haskell/haskell-mode/pull/927> - Yet another parser failure #928 <https://github.com/haskell/haskell-mode/pull/928> - Reloading: haskell-process-file-loadish needs the current buffer as an argument #929 <https://github.com/haskell/haskell-mode/pull/929> - Fix nested layout 1 #930 <https://github.com/haskell/haskell-mode/pull/930> - Filter only sections bearing targets - fixes #534 #931 <https://github.com/haskell/haskell-mode/pull/931> - Honour curly braces in target sections #933 <https://github.com/haskell/haskell-mode/pull/933> - Add failing tests for multiline string literals #934 <https://github.com/haskell/haskell-mode/pull/934> - Mark some indentation tests as passing #936 <https://github.com/haskell/haskell-mode/pull/936> - Remove useless debugging functions #937 <https://github.com/haskell/haskell-mode/pull/937> - Write tests properly, mark them as passing #944 <https://github.com/haskell/haskell-mode/pull/944> - Remove auto-fill code from indentation #945 <https://github.com/haskell/haskell-mode/pull/945> - Improve can grab prefix for completions #946 <https://github.com/haskell/haskell-mode/pull/946> - Remove dynamic indentation showing #947 <https://github.com/haskell/haskell-mode/pull/947> - Indentation of guards with commas is working properly #948 <https://github.com/haskell/haskell-mode/pull/948> - Fix indent for do inside a list #956 <https://github.com/haskell/haskell-mode/pull/956> - Recognize top level constructs in indentation #965 <https://github.com/haskell/haskell-mode/pull/965> - Remove indentation safety hack #966 <https://github.com/haskell/haskell-mode/pull/966> - Change 'w.r.t' to 'with regards to' for clarity #967 <https://github.com/haskell/haskell-mode/pull/967> <https://github.com/haskell/haskell-mode/wiki/Month-in-Haskell-Mode-October-…>Contributors active in October Alexey Khudyakov, Chris Done, Gracjan Polak, Gregor Riegler, Kabelo Moiloa, Marlo Major, vlatkoB <https://github.com/haskell/haskell-mode/wiki/Month-in-Haskell-Mode-October-…> Contributing Haskell Mode needs volunteers like any other open source project. For more information see: https://github.com/haskell/haskell-mode/wiki Also drop by our IRC channel: #haskell-emacs at irc.freenode.net. Thanks!

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Re: [Haskell-cafe] testing for exceptions
by Darren Grant 01 Nov '15

01 Nov '15

Great points. I often run into situations where sketching out non-terminating endpoints leads to a precise domain, but after peer review it becomes clear that a much simpler program would result from compromising with a less precise domain that eliminates these points altogether. Eliminating branching on constructors in Haskell is a common aspect of this refinement, it's true. Cheers, Darren On Nov 1, 2015 03:18, <joachifm(a)fastmail.fm> wrote: The ability to express non-termination is a feature, not a bug. If the program truly cannot produce a useful result for some input, it should crash, the earlier the better. Wrapping the return value ONLY to make a non-total program *appear* total is kind of ugly (and commits you to a potentially inappropriate/nonsensical model for the problem at hand). It is cleaner to either constrain the input to values you're prepared to deal with or crash when the implicit invariant is violated. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe(a)haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe

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