Search results

Lenny222/About Haskell
! What it means ! What it is good for

586 bytes (72 words) - 21:57, 23 April 2021
Monomorphism
...s for several different types - and thus, a function is ''monomorphic'' if it works only for ''one'' type. As an example, <hask>map</hask> is polymorphic. It's type is simply

692 bytes (112 words) - 20:01, 21 May 2017
BayHac2017/dynobud
Be warned that it is non-trivial to get dynobud built as it requires somewhat tricky external C++ dependencies.

325 bytes (45 words) - 00:24, 22 February 2017
BayHac2017/Karya
To get sound you'll need VSTs, a VST host, and jack if it's linux. It's easy to set up on OS X, it might be complicated on linux, but anyone

886 bytes (153 words) - 22:47, 5 April 2017
Abandoning a package
...it. You may wish to also orphan it in this case, to allow others to take it over or claim the namespace. ...package is still good and useful, but no longer have the time to maintain it, you can reach out via the usual community channels (the haskell-cafe maili

957 bytes (167 words) - 22:55, 23 October 2016
First-class module
Because it has also [[Dependent type]]s, it can leverage them so that it is not forced to have a separate module language and a core language.

585 bytes (86 words) - 06:42, 10 August 2022
Diagrams/Install
...haskell.org/platform Haskell Platform], if you don't already have it. Then it should be enough to simply run it will be installed as well.

757 bytes (105 words) - 01:44, 19 April 2015
Blueprint
...low reading a data structure like <hask>Data.Map</hask> while constructing it. It is discussed at length in

346 bytes (51 words) - 15:19, 6 February 2021
Hie-bios
''This article is a stub. Please help expand it.'' ...ng Haskell programs using [[Cabal]], [[Stack]] and other package managers. It is used to specify how [[Haskell Language Server]] and [[ghcide]] set up a

497 bytes (72 words) - 23:38, 31 July 2023
ZuriHac2015/Projects/Gipeda
It generates static files, mostly json-files, using shake to keep track of wha ...ttp://perf.haskell.org/ghc. But it is kept generic and you are free to use it for your own projects as well.

1 KB (201 words) - 08:12, 22 May 2015
Making GHCi scale better and faster
...stops being fun anymore and you start wishing you didn’t have to wait for it to load. If you want it on all the time, you can put the above line in a <code>.ghci</code> file ei

1 KB (245 words) - 18:39, 2 October 2015
Cabal/How to install a Cabal package
...http://hackage.haskell.org/ Hackage] you'd like to try. How do you install it on your system? While it is possible to "install" a library package "globally" it is most certainly a [https://en.wikipedia.org/wiki/Dependency_hell bad idea

1 KB (169 words) - 10:06, 10 March 2021
Diagrams/GSoC
..., and raise the profile of the Haskell programming language. Most of all, it's fun---you get to tangibly experience your contributions in the form of be

1 KB (165 words) - 22:48, 5 March 2014
Haste
...ily modified version of [[haddock]] 1.x for Intellisense (tab-completion). It was [http://www.haskell.org/pipermail/haskell/2005-April/015667.html announ The development of Haste has been abandoned, and as of GHC 6.8.2, it is somewhat bitrotten. A snapshot of the last sources can be found at [[Med

2 KB (310 words) - 05:54, 10 October 2013
Yhc/Primitives
...all. This allows for the possibility that the primitive might block and so it is run in a separate OS thread. ...'t run the primitive call in a separate OS-level thread because we promise it won't block.

2 KB (288 words) - 01:58, 9 April 2021
$
.../hask> has the lowest, right-associative binding precedence (infixr 0), so it sometimes allows parentheses to be omitted; for example: It is also useful in higher-order situations, such as <hask>map ($ 0) xs</hask

1 KB (208 words) - 00:09, 1 October 2016
Strict semantics
It means, that an undefined argument of a function leads to an undefined funct It may be implemented by [[eager evaluation]].

363 bytes (53 words) - 15:18, 6 February 2021
Partial functions
...it much easier to reason about your code and makes "if your code compiles, it probably works" true for your code more often. Usually if you have a partial function, it's because your types are incorrect and you should fix your types rather tha

1 KB (247 words) - 16:53, 15 November 2014
Haskell Web Server
* Björn Bringert cleaned it up and put it to http://darcs.haskell.org/hws/

543 bytes (85 words) - 03:32, 9 April 2021
Default method implementation
It's always a design question, whether to provide default implementions of met ...duces the amount of implementation work for class instances. It also makes it more probable, that no extra super-classes are needed.

2 KB (254 words) - 21:39, 19 September 2016
Xmonad/Notable changes since 0.12
...config. This is now the preferred way to use <code>ManageDocks</code>, as it can be kept up to date with any new hooks that might be added in the future ...W_TYPE_DOCK</code> window type (there is code to handle other windows, but it does not appear to be being used). Notably, this means that if you use <cod

2 KB (420 words) - 18:27, 12 December 2017
Probabilistic Functional Programming
It turns out that random variables establish a monad, namely a list monad wher ...ulate or randomize any simulation without altering the code which defines it.

2 KB (271 words) - 22:15, 27 November 2016
Constant applicative form
...since it is not a [[lambda abstraction]] it contains no variables at all. It may however contain identifiers which refer to other CAFs, e.g. ...ome shared code which will overwrite itself with some graph the first time it is evaluated. A CAF such as

2 KB (255 words) - 06:31, 12 June 2023
99 questions/Solutions/54A
are binary trees: it is just not possible to construct an invalid tree with this type. Hence, it is redundant to introduce a predicate to

1 KB (156 words) - 13:35, 25 December 2016
Haddock
...cumentation of the standard libraries that come with [[GHC]] and [[Hugs]]. It is also supported by [[Cabal]].

684 bytes (90 words) - 02:54, 28 November 2015
Intentionally omitted instance
In an equation for `it': it = 2 + 3 :: Char It is ugly that you have to enable <hask>UndecidableInstances</hask> for this

1 KB (209 words) - 14:08, 22 February 2015
Cabal
...y involved in the creation of packages and the building of their contents. It does not manage packages. ...all non cabal packaged dependencies, it cannot uninstall packages, nor can it automatically upgrade installations.

2 KB (244 words) - 12:34, 2 October 2020
99 questions/Solutions/40
...number theory that has not been proved to be correct in the general case. It has been numerically confirmed up to very large numbers (much larger than w .... Then it looks for a pair of odd numbers where both are prime and returns it as a tuple.

1 KB (226 words) - 19:47, 18 January 2014
Space leak
That means it should preferably leak even when compiled with the latest GHC -O2, but cert It's frustrating to study about leak when the examples given no longer leak fo

1 KB (168 words) - 06:46, 4 February 2015
Infix operator
Putting parentheses around an infix operator converts it into a prefix function: Putting <code>`</code>-marks around a prefix function allows us to use it like an infix function:

1 KB (159 words) - 23:45, 25 June 2021
Commenting
It is generally a good idea to write comprehensible programs, However it is not true that every program can be become comprehensible

2 KB (315 words) - 02:39, 9 April 2021
Calling Haskell from C
It is not uncommon to want to call a Haskell function from C code. Note the foreign export. When GHC sees this, it will generate stubs

1 KB (215 words) - 17:08, 27 June 2019
Syntactic sugar
...ns]] to syntactic sugar. The goal generally being to balance the amount of it available in a language so as to maximise readability -- giving enough free ...of syntactic sugar is as cut-and-dried as some people appear to be making it.

3 KB (490 words) - 01:44, 27 October 2017
NamedAction.dpatch
This actually refers to a text darcs patch, but it works anyways.

94 bytes (15 words) - 15:19, 6 February 2021
BayHac2018/CodeWorld
== What It Is == ...CodeWorld is to be used for middle school aged children. Because of this, it defaults to a simplified variant of Haskell. However, a full Haskell versi

2 KB (275 words) - 21:13, 6 April 2018
Kibro
I've made this page for documenting it, and discussing ideas. ...with cabal install (to make sure all dependencies are there) and then run it on a port like 3000.

1 KB (154 words) - 05:36, 24 April 2021
Multiple instances
How is it possible? ...instance can be defined for the class/newtype pair and it is not orphan if it is defined where newtype is introduced.

2 KB (336 words) - 08:58, 30 November 2016
Binary IO
It's very simple to use, and provides a highly efficient, pure interface It is a part of the base package, so it comes with [[GHC]].

2 KB (254 words) - 19:03, 23 October 2013
Web/Libraries/Templating
...syntax for defining your templates: a Haml-inspired syntax to be precise. It also has support for type-safe URLs, and achieves very high performance by ...e Java StringTemplate library by Terrence Parr, ported by Sterling Clover. It can be used for any templating purpose, but is often used for dynamically g

1 KB (193 words) - 04:57, 26 April 2021
Gtk2Hs/Tutorials
...ses the deprecated Events module and to run some examples with gtk 0.10.1, it is necessary to include "import Graphics.UI.Gtk.Gdk.Events" in the program. A simple example how to show a list and select an entry from it.

1,006 bytes (151 words) - 04:25, 26 April 2021
Diagrams/Dev/AlignedCompose
It seems like a major wart that often, in order to compose diagrams in a certa ...some require <code>Traced</code> and some do not. That is, specifically, it is hard to imagine what type we could give to the hypothetical lens <code>a

2 KB (397 words) - 20:05, 1 June 2015
ARM
...s a [http://en.wikipedia.org/wiki/RISC RISC] instruction set architecture. It is used in most of the mobile phones and in many other consumer electronics ...project with forking jhc.] Kiwamu Okabe created a fork of [[jhc]] and used it to program a [http://en.wikipedia.org/wiki/ARM_Cortex-M Cortex-M3] processo

3 KB (409 words) - 07:55, 19 October 2015
Common Language Runtime
...H JS crew have made some good progress on creating a new target for GHC so it's doable at least. ...this spin, head over to github page, and follow the READMEs carefully. It it also the only Mono compatible solution (but again, may require manual steps

2 KB (405 words) - 10:31, 9 February 2019
Haskell.org infrastructure
...It therefore also determines the policy on the uses of those machines that it pays for. If there are problems with infrastructure, it is good to check [https://status.haskell.org status.haskell.org] to see if

1 KB (208 words) - 23:49, 17 May 2018
GHC/TypeSigsAndAmbiguity
...alas not always. Perhaps this is a deficiency in GHC, but here's one way it can happen: Now GHC finished typechecking the right hand side of <tt>f</tt>, so next it checks that the constraints ''needed'' in the RHS, namely <tt>(C a b1)</tt>

4 KB (716 words) - 11:30, 24 January 2016
Maintenance of standard collection libraries
...rac (http://hackage.haskell.org/trac/ghc/wiki/CollectionLibraries) because it made better sense there.

148 bytes (22 words) - 12:16, 8 June 2023
Hac NYC/Talks
If you'd like to give a talk, announce it here; tell us your name, the title of the talk, a short description. Pleas ...tion of what "univalence" could be and why it is reasonable to expect that it should compute.

2 KB (335 words) - 15:02, 5 April 2014
Hoare Property
...no bugs in it, or write code so complex that there are no obvious bugs in it.

431 bytes (80 words) - 01:34, 17 June 2021
Emacs/Project navigation
...ll buffer which will jump directly to its definition. You can also now use it for [[Emacs/Autocompletion|autocompletion]]. or just <code>M-x customize-group haskell</code> and it's in there.

1 KB (170 words) - 18:23, 11 April 2016
ILogBase
...based, it is limited in number sizes, and has accuracy errors that render it unusable even for simple purposes such as digit counting.

1 KB (173 words) - 01:51, 14 July 2021
Url
The URL library provides a module Network.URL that makes it easy to work with HTTP URLs. ...following example shows how to parse a URL and then add some parameters to it:

829 bytes (129 words) - 15:18, 6 February 2021
Web/Projects and Ideas
* See wai-handler-webkit, though it would be nice if it had better Windows support. Create a WAI handler which uses Webkit to conve ...ai-fastcgi. fastcgi handler for WAI. See the hack-handler-fastcgi package; it should be a simple port.

1 KB (194 words) - 18:09, 27 January 2018
Foldl as foldr alternative
...>. Yes, there is already [[Foldl as foldr|such a page]]! This one explains it differently. ...ges in the recursion. It turns out things will be simpler later if we pull it out:

5 KB (891 words) - 14:21, 3 January 2018
Infinity and efficiency
In general, it is harder to reason about time and memory complexity of an implementation t We want to call it <code>dropWhileRev</code>.

3 KB (422 words) - 21:22, 29 June 2021
Show instance for functions
Why is there a Show instance, but it only prints the type? ...en optimized to <hask>\x -> x :: Int -> Int</hask>. If it's used anywhere, it might have been inlined and optimized to nothing.

3 KB (430 words) - 00:30, 1 February 2016
GHC/Memory Management
...a new value. But GHC is able to efficiently manage garbage collection, so it's not uncommon to produce 1gb of data per second (most part of which will b ...pointed to from scratch. And since values are never modified, neither can it be pointed to later. This is the key property of immutable data.

3 KB (490 words) - 21:19, 21 November 2022
HAC
* Each contest should focus (e.g. graph-related logic) on one topic, but wrap it in some sort of fun game/competition ** By focussing on one topic it will most likely be more informative to people studying those topics

1 KB (213 words) - 01:07, 12 July 2021
Alternatives and extensions for libraries
...nge of Haskell packages and modules. Your help is appreciated in expanding it. When editing this table, please try to keep it in alphabetical order (by package name, then by module name), maintain refl

5 KB (633 words) - 15:16, 6 February 2021
Piq
'''Note''': Piq is not ready for use yet. It's waiting for [[Reactive]] to get into better shape.

835 bytes (127 words) - 03:18, 9 April 2021
Thunk
It is used in Haskell systems that implement [[non-strict semantics]] by [[laz A lazy run-time system does not evaluate a thunk unless it has to.

3 KB (450 words) - 20:07, 19 October 2020
Missing tutorials
...ications, inverses) with vectors and matrices. There are many packages and it takes a while to find the ones serving basic needs (i.e. small arrays, no s ...lications. There's two ways you could go about it. One might be to build it as a Haskell-for-Objective-C programmers, thing. Another might be Mac OS X

1 KB (222 words) - 13:03, 5 March 2024
MonadPlus reform proposal
It is proposed that MonadPlus be split like this: ...us for the Maybe monad should be used as an implementation of morelse, but it is also possible to give an unbiased mplus for Maybe:

4 KB (609 words) - 18:22, 23 June 2015
Prelude
If you wish to program without a prelude or to use a custom version of it you can suppress its automatic inclusion in several ways. The problem is al ...-XNoImplicitPrelude (or -fno-implicit-prelude in older [[GHC]]) that makes it not import Prelude implicitly. The option can be also specified by adding:

1 KB (187 words) - 22:09, 28 June 2021
Denotative
A programming language is trivially denotative if it only permits programs to be defined in terms of denotative expressions. ...O to be managed by the denotative language's implementation, with parts of it written in a non-denotative (I/O-capable) programming language.

4 KB (488 words) - 04:24, 5 April 2024
Lazy evaluation
'''Lazy evaluation''' is a method to evaluate a Haskell program. It means that expressions are not evaluated when they are bound to variables, ...o bypass undefined values (e.g. results of infinite loops) and in this way it also allows one to process formally infinite data.

2 KB (291 words) - 15:20, 6 February 2021
Burton-style nondeterminism
...nvolved in determining a <code>Decision</code> value only occur once: when it is initially used; * Once it has been determined, a <code>Decision</code> value won't change: it remains constant, even if reused.

2 KB (341 words) - 09:18, 22 February 2022
Jhc
...ient programs possible via whole program analysis and other optimizations. It also performs well as a cross compiler and is able to generate Windows prog ...project with forking jhc.] Kiwamu Okabe created a fork of [[jhc]] and used it to program a [http://en.wikipedia.org/wiki/ARM_Cortex-M Cortex-M3] processo

2 KB (230 words) - 22:57, 23 May 2014
Anonymous function
An anonymous function is a [[function]] without a name. It is a [[Lambda abstraction]] and might look like this: <hask>\x -> x + 1</ha ...So if I wanted to add one to each element of a list, here's one way to do it (without anonymous functions):

2 KB (296 words) - 06:56, 12 April 2021
Safe Haskell
Safe Haskell is a Haskell language extension. It is described in detail: As the Safe Haskell paper describes, it "hardens" the Haskell language by providing five properties:

3 KB (471 words) - 03:00, 5 August 2021
Haskell/Lazy evaluation
...e up in #haskell, and it seemed instructive to take the discussion and sum it up into a simple tutorial on lazy evaluation. ...empty list, and any Int. The 'any Int' part is fine, so we need to know if it's passed an empty list. Answering that question forces one step in the eval

4 KB (708 words) - 23:10, 19 April 2021
Euler problems
...:Euler problems|talk page]] for discussion. Many P.E. participants regard it as a global Internet competition which is being compromised by these readil I solved it by using a search engine, does that matter?

2 KB (325 words) - 01:17, 13 February 2019
Xmonad/Guided tour of the xmonad source
Do you know a little Haskell and want to see how it can profitably be ...ut of sync, report it on the xmonad mailing list, or -- even better -- fix it!

3 KB (531 words) - 09:09, 15 August 2017
Humor/Dialogs
so don't tell me how to spend it! I'll ask Mom instead. What do you care where I get them from? It's no extra work for you!

3 KB (445 words) - 15:19, 6 February 2021
ZuriHac2015/Projects
...project. Feel free to add your project or your name to a project below as it was done for [[ZuriHac2014/Projects|ZuriHac 2014]]. ...ed Boltzmann Machines using Accelerate, compiled to Cuda and run on GPU's. It's about unsupervised machine learning. Later: Convolutional RBM's. || Marku

3 KB (355 words) - 14:25, 30 May 2015
GHC/Kinds
...defines a ''promotable'' data type at the term level they are able to use it at the type level too. For instance, the user can write the following examp == How do I use it? ==

2 KB (289 words) - 16:02, 28 February 2014
Applications and libraries/Robotics
:Frob is an Embedded Domain Specific Language for controlling robots. It is built using the principals of Functional Reactive Programming, as develo ...It supports direct commands, messages and many sensors (also unofficial). It has also support for a simple message-based control of a NXT brick via remo

1 KB (178 words) - 12:02, 8 June 2023
Avoiding partial functions
we replace it by combination of check and computation of f. You may implement it with the partial function <hask>minimum</hask>.

3 KB (506 words) - 04:03, 4 September 2017
Upgrading from MTL 1 to MTL 2
...version 2. Most of the remainder require only small changes to upgrade to it, though that will usually render them incompatible with version 1 without s ...mers] package. You may wish to check it's the same, so you can just delete it.

2 KB (374 words) - 00:43, 9 April 2021
Gentoo
...packages that are distributed via [http://hackage.haskell.org/ Hackage] as it allows us to use automated tools. ...their dependencies changed (ala revdep-rebuild/reconcilio/etc.). That is, it will rebuild packages corresponding to the libraries listed by "ghc-pkg che

4 KB (592 words) - 08:43, 1 September 2022
From a newbie II
...y good programmer I decided to take a look. Ugh, what the f*ck is this? So it never went past taking a glance from the examples in wikipedia or haskell.o ...r boredom I decided to resume my Haskell lessons. Naturally, I am enjoying it more than ever, since this 'feeling' that learning something \this\ new giv

2 KB (390 words) - 15:19, 6 February 2021
HQK
...eless, you can [http://community.haskell.org/~jeltsch/hqk.tar.gz download] it. Here are some building tips from Sönke Hahn: ...Wolfgang Jeltsch]], would be happy to hear from you whether you think that it is sensible to transform the current version into something that can be rel

2 KB (285 words) - 06:52, 22 June 2021
DDC/ReleaseNotes-Alpha1
:The GC used to work on 64 bit machines also, but it hasn't been tested for a long time. [http://code.google.com/p/disciple/issu ...t support functions being partially applied to unboxed arguments. Nor does it support unboxed data being free in the closure of a function, or being used

2 KB (394 words) - 11:57, 19 April 2021
Gtk2Hs/Tutorials/TreeView
...the web i could find. Therefore i post here the solution I have working - it is not optimal and I would appreciate comments. ...our names and after clicking on one it says which one you selected. i hope it is useful for others!

2 KB (280 words) - 00:46, 9 April 2021
99 questions/Solutions/5
...e wasteful than the one in Prelude as it repeatedly reconses the result as it is accumulated. The following variation avoids that, and thus computational

1 KB (148 words) - 12:06, 11 August 2017
Physical units
...th integral seconds and fractional seconds). If this can in fact be done, it could also be used to model coordinate system axes in, say, Geometric Algeb ...y of handling it without forcing a choice of basis. I'm also not sure how it would work -- the whole point of GA is to incorporate areas, lengths, volum

3 KB (521 words) - 07:04, 13 September 2016
Diagrams/GHC7.6
...in time to try to find an ''earlier'' version of diagrams which "works". It finds diagrams-0.2.2.3, which is quite old and happens to be the last time

1 KB (207 words) - 15:18, 6 February 2021
Worker wrapper
It is sometimes easier or more efficient to write functions which have particu however this will be more efficient if it were written

2 KB (333 words) - 12:44, 4 June 2018
Diagrams/Dev/ReviewingAndMerging
...s reading carefully through their proposed changes and commenting; ideally it also means downloading and testing their code.Some guidelines for co ** ''Be clear''. Make it clear what action(s) are necessary to improve or correct the code. Clearly

4 KB (614 words) - 16:36, 9 May 2015
Quotes
<LoganCapaldo> No, it just lifts a monad in each hand <oerjan> EvilTerran: no, it's for turning cotheorems into ffee.

3 KB (561 words) - 02:55, 26 April 2021
ZuriHac2015/Projects/FRPGames
...re obvious caveats in all FRP implementations, Yampa included, so I'd love it for you to help me figure out how to make Yampa better. You do not need to ...esigners to share assets. I tend to use SDL2 and 2D graphics, only because it's easier. You can also talk to the LambdaCube3D people and combine FRP and

3 KB (578 words) - 15:24, 29 May 2015
Budapest Hackathon 2016/Projects
of course work assignments, mid-term and final examinations. It is almost fully implemented in Haskell based on the Snap framework, it uses the

5 KB (679 words) - 14:07, 5 August 2016
Import modules properly
...ntifier that you never needed but only annoyed you, annoys you again, when it was meant to not bother you any longer! The first variant of import does no ...ll too often I find an old module that cannot be compiled any longer since it uses identifiers that do no longer exist. If the module imports implicitly

5 KB (816 words) - 08:28, 2 May 2015
Num instance for functions
It is possible to write a <hask>Num</hask> instance for functions in Haskell: The usefulness of this instance is debatable, and it is not currently part of [[Language and library specification|the language

1 KB (145 words) - 01:24, 28 December 2014
Hack-Nix
* It works the same way no matter which linux distribution you're using # In this example it's used to remove base >= 4 from the

5 KB (726 words) - 10:39, 5 January 2018
Let vs. Where
...sense of "[[Declaration vs. expression style]]", however there is more to it. ...ortant to know that <hask>let ... in ...</hask> is an expression, that is, it can be written wherever expressions are allowed. In contrast, <hask>where</

4 KB (716 words) - 07:41, 26 January 2019
Use of language extensions
However, when it comes to designing libraries one should carefully think about which extensi ...ram and the compiler suggests to use a language extension to resolve that. It is a quick fix to solve the problem by enabling the extension, but if you d

3 KB (387 words) - 05:21, 12 July 2021
Data declaration with constraint
The designers of Haskell 98 do now think, that it was a bad decision to allow constraints on constructors. GHC as of version ...en something pattern matches a <hask>Cons x</hask>, the context comes with it.

2 KB (312 words) - 23:26, 19 September 2016
Haskell-language-server
.../ Ghcup] can install HLS, but after installation, you'll need to integrate it with an editor. The [https://github.com/haskell/haskell-language-server#con ...e-them-all.html</ref> Over time, this project became the HLS, which allows it to be used with many IDEs and code editors.

1 KB (157 words) - 00:07, 26 April 2024
Web/Framework Interfaces
...like WAI, it uses lazy bytestrings for request and response bodies, making it easier to use for some. Many backends are available, for numerous backends;

2 KB (217 words) - 12:02, 19 April 2024
Roll your own IRC bot/Source
...of the source code for the bot described in [[Roll your own IRC bot]], but it fell out of date with the article (and became uncompilable). That page alre

284 bytes (52 words) - 00:57, 17 June 2015
QualifiedDo
...ps://gitlab.haskell.org/ghc/ghc/-/merge_requests/3436 merged] in 2020, and it is available in GHC 9 and later releases.

347 bytes (52 words) - 23:50, 6 December 2020
A new list type
...lso computes and stores the size of the source list - if anybody still has it.) The really interesting case is <hask>select</hask> (which is equivalent t ...id]] for why you should try to avoid calling <hask>length</hask>. Although it probably requires quite a change of mindset for a non-Haskeller to apprecia

3 KB (587 words) - 15:19, 6 February 2021
Diagrams/Install/Install-cairo
...through your operating system's package manager or otherwise. After that, it should ''ideally'' be enough to run ...hs-buildtools</code> in the past then you probably don't need to reinstall it; though note that in order to build <code>cairo</code> under GHC 7.6 you ne

3 KB (511 words) - 01:45, 19 April 2015
Encoding issues
...ch a type is either a list of bytes, equivalent to <hask>[Word8]</hask> or it is a string, a list of character, <hask>[Char]</hask>. ...t will be the encoding from the current locale (usually UTF-8). On windows it will be based on a Byte order mark for file IO, while the output encoding c

2 KB (307 words) - 13:45, 23 May 2021
99 questions/Solutions/34
...ke coprime from the previous exercise and give it to filter, which applies it to each element of a list from 1 to one less than the number, returning onl This example uses Data.Ratio to ensure no precision is lost. It also relies on a function primeFactors (not shown) that returns a list of a

1 KB (224 words) - 19:44, 18 January 2014
99 questions/Solutions/35
...imeFactors. primeFactors checks to make sure the factors are prime. If not it prime factorizes them. In the end a list of prime factors is returned. ...ial division, speeds it up a lot (especially as memoized). Or you can find it on [[prime numbers]] haskellwiki page.

3 KB (485 words) - 19:45, 18 January 2014
MultiCase
It is proposed that Haskell allow multiple pattern matches in a case statement ...ntax. Using `,` is also a problem for nested options such as this, because it conflicts with pattern matching on tuples:

3 KB (470 words) - 23:09, 11 July 2021
Seq
..., and returns the second. However, it also has the important property that it is always strict in its first argument. In essence, <code>seq</code> is def ...esn't evaluate anything just by virtue of existing in the source file, all it does is introduce an artificial data dependency of one value on another: wh

4 KB (716 words) - 14:44, 8 January 2024
Lambdabot/Building
Fortunately, the [[darcs]] repositories of most of these packages do support it. Apply a patch to lambdabot and install it:

2 KB (271 words) - 03:32, 14 August 2021
GHC/Type system/PolyKinds
...retin/papers/fc-kind-poly.pdf Giving Haskell a promotion], the paper about it. The former must mean what it always means in Haskell, namely

2 KB (242 words) - 23:38, 24 July 2021
Diagrams/Dev/IRCHooks
It's helpful to have repositories in the diagrams organization on github gener ...ll be sent to the IRC channel for pushes and pull requests only. However, it is useful to get notifications for other sorts of events too. Strangely, t

2 KB (329 words) - 13:42, 17 October 2014
Cookbook/Files
...and will be closed when the resulting string is garbage collected. Closing it manually may result in a random truncation of the input.'' ...kes a function from <hask>string</hask> to <hask>string</hask> and applies it lazily to the input from stdin, writing the output to stdout.

2 KB (345 words) - 21:08, 6 January 2019
How to get rid of IO
...ing the code expecting <code>regularThingie</code>: If you're able to make it into a function e.g: ...r <code>IO</code> value (The result will depend on the environment because it uses a value dependent of the environment).

4 KB (726 words) - 05:08, 6 April 2022
Cookbook/XML
...(limited) experience, I could only get [[HXT]] to do everything I wanted. It does make heavy use of [http://haskell.org/arrows/ Arrows].

250 bytes (38 words) - 02:01, 26 April 2021
Bad type errors
...s you that your program doesn't make sense. Unfortunately, the description it provides for the problem '''''also''''' does not make sense.

247 bytes (40 words) - 13:50, 23 May 2021
X-DSP
...unified interface to different audio signal processing systems. Currently it supports Csound.

251 bytes (34 words) - 21:24, 29 June 2021
HDBC-ODBC MS SQL under Linux
You can test it from a [[GHC/GHCi| ghci]] prompt (obviously you'll need to change the conne If you are not using a DSN, it's critical to explicitly set the Port in the connection string

1 KB (210 words) - 11:52, 19 April 2021
BayHac2018/haddock
...the markup types we don't have to pay the cost of 'String' and let GHC use it's efficient, internal string types.

1,000 bytes (161 words) - 18:06, 15 April 2018
Xmonad/Config archive/Template xmonad.hs (darcs)
If you want a good configuration to start from, it's quite simple. ...<code>hookName baseConfig <+></code> to the new value. (You may also make it the first item in a <code>composeAll</code> for the <code>manageHook</code>

3 KB (366 words) - 17:06, 11 January 2018
Functional programming/Old version
No, there is more in it. On the one hand this is a powerful property, since it gives you guarantees you cannot have in imperative languages.

2 KB (378 words) - 23:58, 5 April 2021
Currying
It holds however the curried form is usually more convenient because it allows [[partial application]].

4 KB (669 words) - 02:17, 3 November 2023
LondonInfrastructureHac2015
...e place in London during the two days following the Haskell eXchange 2015. It will be hosted at Pivotal Labs, London. Everyone is welcome, beginners and ...d merge projects started at the first and to hopefully celebrate progress. It is, however, not at all necessary to commit yourself to attending both Hack

2 KB (307 words) - 08:59, 10 October 2015
Type variables instead of concrete types
But the signature is not as expressive as it could be. It is fixed to a concrete type, say <hask>Double</hask>.

3 KB (531 words) - 15:19, 6 February 2021
BayHac2017/CodeWorld
== What It Is == ...CodeWorld is to be used for middle school aged children. Because of this, it defaults to a simplified variant of Haskell. However, a full Haskell versi

4 KB (593 words) - 01:45, 27 March 2017
Simple monad examples
...> on its left-hand side; or if its left-hand side is a <code>Just …</code> it strips off the <code>Just</code>, and passes the contents into the function

1 KB (188 words) - 11:16, 22 October 2022
Tomato-rubato
== What is it? == ...o-openl] package which allows you to play raw audio data on your speakers. It has an extremely simple interface and uses [http://hackage.haskell.org/pack

1 KB (183 words) - 22:25, 4 January 2015
Type classes are for reusability
(Actually, it was not necessary to bundle the number literal feature expressed by the <ha But it is generally accepted that number literals are reserved for objects that al

2 KB (322 words) - 04:01, 6 April 2021
Bottom
...as '&perp;' and in LaTeX as '\bot' (within math mode). In plain ASCII, it's often written as the extremely ugly character sequence '<code>_|_</code>' If it were not, the compiler could solve the [http://en.wikipedia.org/wiki/Haltin

2 KB (306 words) - 09:04, 16 June 2014
Wadler's Law
about half saying that > is wonderful, and half saying it is awful. Under these circumstances, Paul's ruling seems right: it is pointless

4 KB (583 words) - 10:26, 26 December 2017
Switching type classes at runtime
It is possible to create a type class instance at runtime by coercing a value We'd like to turn this into a "IOError", so that it can be caught:

1 KB (215 words) - 10:06, 3 August 2015
Simple Unix tools
tools, it is possible to compile a single monolithic binary and have it detect what name it is run by and then act appropriately. This is the

6 KB (842 words) - 05:27, 8 February 2016
Orphan instance
...ule somewhere. It is almost impossible to assert that, or put differently, it would reduce the composability of libraries considerably. ...d, too. If you want to define a new instance then the compiler will reject it immediately.

3 KB (489 words) - 10:13, 31 May 2015
Community server (defunct)
It has now been retired: http://blog.haskell.org/post/7/the_future_of_communit

308 bytes (49 words) - 04:03, 8 June 2023
PortAudio
In Haskell it is supported by

361 bytes (51 words) - 03:53, 26 April 2021
Generics
...resent in compiled code. So the word "generic" is somewhat overloaded, and it may be desirable to use "polymorphic" when possible. ...implementation is necessary, similarly to <hask>Show</hask>, for instance. It's described in a [[GHC.Generics|separate wiki page]].

4 KB (598 words) - 02:44, 13 February 2021
Hac Boston/Projects
If you need a place to host a project so that others can help with it, we suggest ...have a project that you want to work on at the Hackathon, please describe it here.

1 KB (193 words) - 23:52, 27 July 2014
Applications and libraries/Bioinformatics
...rtunately is hard to tune to give optimal results. Unless you plan to fix it, use CAP3 instead. ...spe and L. De Raedt (1997) Mining Association Rules in Multiple Relations. It is described in Clare, A. and King R.D. (2003) "Data mining the yeast geno

2 KB (339 words) - 18:30, 6 December 2013
POSIX process group API reform proposal
It is proposed that <tt>System.Posix.Types</tt> have a new type <tt>ProcessGro It is proposed that <tt>System.Posix.Process</tt> have these functions, (at le

2 KB (359 words) - 00:16, 17 June 2021
Web/Testing and Verification
...s to communicate with a Selenium Remote Control server. This package makes it possible to use Haskell to write test scripts that exercise web application ...ing WAI applications. Developed initially for testing wai-extra and Yesod, it should prove generally useful.

2 KB (207 words) - 00:35, 17 January 2017
Netwire
...mming]] library that provides both an applicative and an arrow interface. It allows you to express time-varying values with a rich event system. Netwire's FRP framework is intended to be used for continuous applications. It replaces the traditional big main loop with its global state and event call

3 KB (433 words) - 21:39, 2 October 2014
DDC/PolymorphicUpdate
...ype <hask>(forall a. [a])</hask>, but suppose we update the box containing it at two different types... ...calls to <hask>getSet2</hask>. When <hask>makeGetSet</hask> was evaluated it created a shared mutable object (the <hask>box</hask>) and then returned fu

3 KB (432 words) - 00:47, 24 February 2018
GPipe
...ng unit). It is an alternative to using OpenGl, and has the advantage that it is functional and statically typed as opposed to OpenGl's inherently impera ...have something to contribute with, just send me a patch and I might merge it into the trunk.

3 KB (460 words) - 15:27, 6 January 2016
Language extensions
when it is useful]] and what risk it may bring to your program. * {{GHCUsersGuide|exts/tuple_sections||section on TupleSections}} It allows tuples to be partially applied.

3 KB (379 words) - 05:36, 9 September 2021
Scoped type variables
...possible to specify the particular type of a function in situations where it is not otherwise possible, which can in turn help avoid problems with the [ It is used like <hask>x `asTypeOf` y</hask> and has the same value like <hask>

3 KB (435 words) - 22:56, 12 June 2021
99 questions/Solutions/49
...f n-1, prepend a 0 to each word, take the Gray code for n-1 again, reverse it and prepend a 1 to each word. At last we have to append these two lists. Fo ...etely different solution (using folds) that is way more efficient, because it needs just the space which is occupied by the list itself:

2 KB (298 words) - 03:02, 7 June 2021
Trash/DDC/ClosureTyping
...original definition of <hask>g</hask> so is shared between applications of it. ...t the <hask>Int</hask> is free in its closure so is shared by all calls to it. The type system does not generalize regions which are free in these closur

3 KB (472 words) - 04:20, 8 June 2023
Constructor
...] constructor''' may have zero or more arguments, if it has zero arguments it is called a ''nullary'' type constructor (or simply a '''type'''). An examp ...sk>, <hask>Maybe String</hask>, or even <hask>Tree b</hask>, in which case it will be a tree of tree of <hask>b</hask>. The data type is polymorphic (and

6 KB (1,060 words) - 16:51, 18 June 2021
ZuriHac2015/Projects/hackage-security
hackage-security is an effort to bring security to the cabal environment. It is based on The Update Framework (TUF) that has been inspired by tor's buil ...g to hackage servers in sync. Re-write the download and/or upload part so it provides TUF security guarantees for the mirror and its users.

2 KB (233 words) - 11:01, 27 May 2015
Cabal-dev
cabal-dev is a tool for managing development builds of Haskell projects. It supports maintaining sandboxed cabal-install repositories, and sandboxed gh

377 bytes (51 words) - 07:14, 9 June 2023
99 questions/Solutions/6
Here's one to show it done in a fold just for the fun of it. Do note that it is less efficient then the previous 2 though.

2 KB (320 words) - 00:08, 8 July 2019
Idiom brackets
Since f is not a pure function, it's f :: x -> y -> m c. The correct form would be I thought I'd present it as a curio illustrating part of the design space, but

2 KB (365 words) - 18:50, 19 September 2017
Power function
...ately, the Haskell implementation does not try to be too clever here. But it does so at another point: One can refine the set of power functions further as it is done in the [[Numeric Prelude]]. In this library, the more general the

4 KB (574 words) - 21:34, 10 March 2016
Fairbairn threshold
it or inlining it. There are reasonable exceptions for especially common idioms, but it does

2 KB (321 words) - 14:41, 4 May 2020
Composing functions with multiple values
such that it meets the needs of <hask>(++)</hask>? It is

1 KB (233 words) - 23:09, 26 January 2016
Automatic Differentiation
However, it becomes more difficult for vector functions, when computing the derivatives Forward mode is suitable when you have fewer arguments than outputs, because it requires multiple applications of the function, one for each input.

3 KB (413 words) - 04:23, 7 October 2013
Monad/ST
...read" of computation cannot exchange mutable state with the outside world, it can only exchange immutable state. ...llocate mutable memory, then you initialize and play with it, then you put it away and return a normal Haskell value.

5 KB (802 words) - 05:38, 4 August 2021
Section of an infix operator
...and it represents a function which intuitively takes an argument and puts it on the "missing" side of the infix operator.

2 KB (233 words) - 17:58, 31 March 2017
Syntactic sugar/Pros
...ge shall give arguments why syntactic sugar is useful, give examples where it is useful and show why the arguments against syntactic sugar don't matter.

322 bytes (47 words) - 03:29, 14 August 2021
DDC/ClassSystem
...ables. If a region variable in the return type of a function is quantified it means the region is ''fresh'', ie the data was allocated by the function it ...just static <hask>Float</hask> and not a function that does allocation, so it doesn't have a <hask>forall</hask>.

5 KB (774 words) - 12:35, 8 June 2023
Gtk2Hs/Tutorials/ThreadedGUIs
...there was little accurate info on how to do multithreaded GUI in gtk2hs. It's trivial. ...you have to know, is that you MUST compile your program with -threaded for it to work properly. Otherwise you will get random hangs.

4 KB (613 words) - 21:06, 7 October 2014
Hat
...e Haskell debugger, see http://projects.haskell.org/hat/ for more details. It can be downloaded from [http://hackage.haskell.org/package/hat Hackage].

374 bytes (49 words) - 18:21, 24 February 2014
Iteratee I/O
...r, while it is good enough for simple programs, its unpredictability makes it unsuitable for practical use. ...common beginner mistake is to close a file before one has finished reading it:

4 KB (653 words) - 12:02, 19 April 2024
Top-level vs. local recursion
* It clearly shows that the <hask>f</hask> is not "altered" in the recursion. ...er in laziness or performance. Their names are only slightly different and it happened too often that after ''copy&paste&name-change'' the recursive call

1 KB (226 words) - 23:02, 18 April 2021
OCaml
OCaml is strict by default, although it has some facility for introducing laziness. OCaml is impure: although it makes heavy use of immutable data, it also has mutable references and arrays available, and IO is performed by or

2 KB (293 words) - 16:34, 15 May 2023
Guess a random number
...self randomly generated. Along the way, it became a game. At this point, it also demonstrates simple interaction with the environment (prompting users, ...y or mind-blowing about it; it's my first Haskell program, and I just hope it can help out other newbies. Comments, criticism, and rewrites are welcome.

5 KB (787 words) - 15:17, 6 February 2021
Questions and answers
;Q. I just wrote this really cool program! Who can I show it to? ...s interesting program that someone else might find useful. Where can I put it?

6 KB (915 words) - 06:17, 23 July 2020
LLVM
It is developed by the University of Illinois. It is implemented on many platforms, amongst others the [http://www.ipodobserv

2 KB (204 words) - 11:22, 2 October 2020
Bluetile
time is the most limited resource among the majority of users. It's good if you can configure a software in every respect. It's better if you

5 KB (770 words) - 23:20, 11 July 2021
Xml
...nce is anything which has some convention for generating an Element out of it. ...(qualified name) denotes a name with its qualifying namespace attached to it.

2 KB (327 words) - 08:14, 20 February 2014
Diagrams/Dev/Expression
...ntation for every existing class); others, e.g. algebraic data types, make it easy to add new operations (just write a new function) but annoying to add ...equire changing existing backends, which will simply not be able to render it) but also new backends.

8 KB (1,309 words) - 19:09, 18 May 2014
Glome
Glome is a ray tracer written by Jim Snow. Originally it was written in Ocaml, but the more recent versions are written in Haskell. ...vailable on Hackage called glome-hs, which renders into an OpenGL window. It probably won't work with recent versions of GlomeTrace.)

4 KB (684 words) - 19:46, 11 April 2014
Applications and libraries/Data structures
....haskell.org/ghc/docs/edison/ earlier version of Edison] by Chris Okasaki. It provides sequences, finite maps, priority queues, and sets/bags. ([http://w :*It's easy to migrate from standard Lists/Sets/Maps to the new package. The pac

17 KB (2,508 words) - 07:09, 8 June 2023
Unde gasim lucrarea lui Graham Hutton despre fold ?
...tt.ac.uk/~gmh/foldl.pdf A tutorial on the universality of fold - Download it from here.]

356 bytes (63 words) - 03:29, 9 April 2021
Computer science
...utabilty theory: [[Exact real arithmetic]]. For me, it was surprising, how it connected problems in mathematical analysis, arithmetic and computability t ...n experimentable, playable incarnation of [[recursive function theory]] -- it could yield a playground for learning concepts like [http://www.madore.org/

3 KB (357 words) - 15:18, 6 February 2021
Laziness is not always good
You find that it is not <hask>mappend mempty undefined = undefined</hask>, but <hask>mappend I think it is the latter one, because a <hask>Monoid</hask> instance implicitly promis

2 KB (342 words) - 09:27, 9 June 2023
Xmonad/Installing xmonad
# the contrib package depends on xmonad so it gets also installed It may also be convenient to perform various startup operations like adjusting

5 KB (613 words) - 20:56, 22 November 2016
BayHac2017/hopes
* I will be happy any way it turns out but I would prefer pizza and swag. ...ith proficient Haskellers and walk through their code and my code. I hope it will be friendly and inviting.

4 KB (596 words) - 18:52, 27 January 2017
Case
It is however in the [http://hackage.haskell.org/packages/archive/utility-ht/0 you may call it <hask>?</hask> like in C,

3 KB (411 words) - 11:36, 11 June 2020
Taking over a package
* The current maintainer can do it directly on the package maintainer group page on Hackage: <code>https://hac This situation is more tricky because it involves overriding the normal rights of authors/maintainers.

3 KB (427 words) - 21:49, 27 April 2023
99 questions/Solutions/90
This is easy to understand, but it's also quite slow, as it generates and tests N^N possible N-queen configurations. The key to speeding it up is to fuse the composition <hask>filter test . generate</hask> into a se

3 KB (451 words) - 17:56, 30 September 2019
Vogonism
...that manner, information is avoided to be present where recipients expect it due to related information already having been transmitted over the same ch ...y the authors, and not even those after a couple of months) can comprehend it, as well as to code that has problems understanding itself. Examples for th

1 KB (224 words) - 01:34, 17 June 2021
Distributions
...' can download GHC, [[Haskell Language Server]] and [[cabal-install]], and it can auto-update. ...is an easy-to-use integrated programming environment for Haskell on OS X. It is a one-click install of a complete Haskell system, including Haskell comp

4 KB (620 words) - 19:54, 9 December 2020
Haskell projects needing help
Windows, X11, and MacOS X. Furthermore, it is a mature library (in There is no such project currently going on, but someone should start it. It probably needs several people to make sure that the project will run to til

6 KB (833 words) - 00:37, 25 March 2015
If-then-else
...ns, the <hask>if-then-else</hask> syntax was defined in Haskell98. However it could be simply replaced by the function <hask>if'</hask> with ...tool can process it without hassle. Haddock can generate documentation for it, a text editor can make suggestions for values to insert, Hoogle can retrie

6 KB (937 words) - 05:34, 10 December 2020
WxHaskell/Contribute
However, it is hard to find out which features are particularly interesting, the hardne :(It is best to discuss this on the wxHaskell developer mailing list first.)

4 KB (687 words) - 14:54, 8 October 2015
AI/Genetic programming/Evolutionary chess
So, for about 2 years or so, I've been batting around the idea of what it would look like to apply genetic programming to chess. Here's a non-technic ...platform on which to build this idea. To be a little more technical about it than I was in that overview, here's some more haskell-ish ideas.

5 KB (819 words) - 01:04, 9 April 2021
Memory leak
but it is easily possible to produce memory leaks, especially in connection with [ Note that a leak will not only consume more and more memory but it will also slow down the [[garbage collector]] considerably!

4 KB (648 words) - 14:59, 13 June 2016
Hommage
It was developed 2005-2006 and runs with the current version of the Glasgow Ha

482 bytes (58 words) - 04:54, 12 July 2021
Homework help
...now Haskell well had to learn it once, and if they were creative, they did it in the appropriate way: First by attempting to understand each issue on th ...doesn't mean that you can't ask for homework help. Far from it! However, it does mean the following:

8 KB (1,447 words) - 08:49, 15 September 2015
KURE
...ped strategy control language in the tradition of Stratego and Strafunski. It is intended for writing reasonably efficient rewrite systems, makes use of ...ate Haskell) to provide the basic rewrite abilities inside [[Hera| HERA]]. It was rewritten in late 2008, and is published on hackage. KURE will be used

1 KB (185 words) - 00:27, 12 July 2021
Pairs of identifiers
It is even better if many libraries would share the same scheme. It would be great if the discussion lead to a more streamlined collection

1 KB (222 words) - 22:51, 18 April 2021
ZuriHac2015/Projects/fficxx
...ugh this project has potentially significant effects on haskell ecosystem, it has been stalled for a quite long time. In this hackathon, we would like to Currently, it uses ugly string template approach, but we would like to use clean abstract

2 KB (344 words) - 12:43, 26 May 2015
Poorly named things
* forkOS - forkOS does not create an OS-level thread. It creates a lightweight thread, the same as forkIO. The only difference is w

398 bytes (64 words) - 15:19, 6 February 2021
Shared libraries and GHC
* shared libraries include all code from a library, even if it is unused ...you can get when a majority of values are not strictly evaluated. However, it is only relatively efficient: evaluation jumps around a lot more than in st

4 KB (701 words) - 13:33, 24 December 2018
Threepenny-gui
== What is it? == ...ML at your disposal when creating user interfaces. This is a blessing, but it can also be a curse, so the library includes a few layout combinators to qu

6 KB (786 words) - 00:53, 12 February 2022
Humor/Erlkönig
> You're giving it a tuple of Int, so we can substitute Int for 'a' in It's Haskell with his child Hank;

5 KB (787 words) - 11:02, 26 December 2017
Simple RWST use
...putStrLn "I'm thinking of a number between 1 and 10, can you guess it?" (EQ, _) -> do lift $ putStrLn "Got it!"

2 KB (237 words) - 19:47, 9 January 2018
Live-Sequencer
While doing so it highlights active terms and shows the result of the term reductions. The nice thing is, that the user can change the program while it is performed.

2 KB (314 words) - 09:50, 26 September 2018
Enumerator and iteratee
...e iteratee finishes, it outputs an accumulator. If the iteratee continues, it outputs nothing (i.e., <hask>()</hask>). The distinct feature of iteratee is that it can say after which list element an iteratee finishes. An iteratee says thi

6 KB (927 words) - 12:02, 19 April 2024
Frag
Cheong. It is licensed under the GPL. The design and implementation of * Frag has portability problems. It is known to work on i386 and AMD64, and known not to work on big-endian sy

3 KB (386 words) - 11:31, 5 May 2017
Web/Databases and Persistence
| http://acid-state.seize.it/ | [http://mirror.seize.it/acid-state/examples/ Stand-alone examples], [http://happstack.com/docs/cras

5 KB (701 words) - 02:22, 26 April 2021
Haiku
It is like Haiku It is only code! 

4 KB (621 words) - 05:56, 26 April 2021
Pure
...ked in a different context or at a different time with the same arguments, it will produce the same result. In comparison, procedures or subrou * it only permits programs to be defined in terms of pure definitions,

2 KB (290 words) - 08:52, 24 April 2024
Diagrams/Dev
...askell-style-guide/blob/master/haskell-style.md Coding style guidelines]. It's not worth being super picky about these, but in general they are quite go ...s with ambiguous type variables. This comes up a lot when using diagrams, it would be nice to see this ticket resolved.

3 KB (338 words) - 19:39, 16 October 2016
Calitatea si inspectorul cozonacilor


391 bytes (64 words) - 05:12, 24 April 2021
Almost Haskell
Almost code is code that sounds like it might be real Haskell, but isn't.

328 bytes (43 words) - 01:32, 14 July 2021
HaskellImplementorsWorkshop
..., aimed at bringing together the people behind the Haskell infrastructure. It provides a forum where the people working on compilers, tools, or libraries

2 KB (193 words) - 13:11, 10 January 2024
Monoid
...when you combine it with others (this is called the ''identity'' element). It is closely related to the [[Foldable]] class, and indeed you can think of a -- defining sconcat is unnecessary, it has a default implementation

7 KB (1,101 words) - 02:30, 27 December 2019
Tail recursion
1 to it, or consing another element onto the beginning of it), it is ...sk>). This allows the result of the function to be consumed lazily, since it can be evaluated up to the data constructor and the recursive call delayed

3 KB (581 words) - 14:04, 5 May 2019
Functor-Applicative-Monad Proposal
...ction] with [[Roles]]. Will "probably be fixed in the future", but for now it's off the table. ...e <hask>pure</hask>. Instead, leave <hask>return</hask> in Monad, and give it <hask>pure</hask> as default implementation.

10 KB (1,557 words) - 11:46, 24 October 2015
99 questions/Solutions/27
...the possibilities for this choice in <hask>ts</hask>) or if we don't want it in the combination (<hask>ds</hask> collects the possibilities for this cas And a way for those who like it shorter (but less comprehensive):

2 KB (410 words) - 19:40, 18 January 2014
Hugs
...d, and is based on the stable but superseded Haskell 98 standard. However, it still works quickly and correctly, can be installed quickly without adminis ...xceptionally portable. If Hugs can't be installed on your machine, report it as a bug!

3 KB (343 words) - 20:18, 9 December 2020
Functor hierarchy proposal
It might also be useful to split a <hask>Pointed</hask> class from the <hask>A ...k> functionality by itself could be useful, for example, in a DSL in which it is only possible to embed values and not to lift functions to functions ove

2 KB (294 words) - 05:14, 8 June 2023
HaskellITA
[https://www.haskell-ita.it/ Haskell ITA] is an Italian community of Haskellers. * Other events are listed at https://www.haskell-ita.it/events/

476 bytes (70 words) - 14:33, 27 March 2022
Foldl as foldr
...ttp://www.willamette.edu/~fruehr/haskell/evolution.html lean so far right] it came back left again.) It holds

5 KB (822 words) - 10:42, 2 February 2018
LUI
...has a very simple pure semantic model. It is a function from a model that it is editing to an image, size, and mapping of event groups to documentation ...ected child. A FocusDelegator will pass its focus to its selected child if it is in child mode, and stop doing so when going to self-mode.

4 KB (663 words) - 08:07, 23 May 2021
Performance/Data types
...detect when this is the case and optimise away the wasted evaluation, but it is hard to do this well (GHC does a poor job, currently). ...s, such as tuples. A single-constructor datatype can be ''unpacked'' when it is passed to a strict function. For example, given this function:

5 KB (782 words) - 16:41, 4 February 2023
HacFreiburg2017/ListOfProjects
...the data type itself. Currently when haddock sees a name in an export list it tries to find its corresponding declaration. From an ASTs viewpoint single ...ithub.com/haskell/haddock/pull/645 laid the groundwork for such a feature. It adds a command line parameter which dumps an interface file to json. If yo

3 KB (381 words) - 14:33, 4 August 2017
UnicodeByteString
It provides a most general conversion function with type: -- | An error in the conversion process. If this occurs it will be the

5 KB (717 words) - 15:20, 6 February 2021
DDC/ReleaseNotes-Alpha1.1
...t support functions being partially applied to unboxed arguments. Nor does it support unboxed data being free in the closure of a function, or being used ...ining monomorphic type vars is unsound because client modules could update it at different types. [http://code.google.com/p/disciple/issues/detail?id=12

4 KB (583 words) - 00:53, 9 April 2021
Thompson-Wheeler logo
It has been tested for TeXLive 2007 and TeXLive 2008. It requires a version of TikZ that includes the file pgfkeys.sty (unfortunatel ...se unfamiliar with TikZ, it stands for "TikZ ist kein Zeichenprogramm" and it allows one to make drawing ([http://www.texample.net/tikz/ like these]) dir

3 KB (488 words) - 16:11, 3 August 2013
TypeDirectedNameResolution
It's hard to gauge how much people like proposals like this, so let's try the ...he language. I have not much missed it yet, so I don't feel strongly about it, though.)

7 KB (1,198 words) - 05:55, 10 December 2020
Brand
...top, using the dark blue color of the palette, with a border at the top of it using the lighter blue color. [http://tryhaskell.org/ocean/components.html# * The web site's logo should be below the navigation, not inside it, unless it is properly resized and looks cohesive with the Haskell logo.

3 KB (483 words) - 23:13, 22 May 2014
Monk upgrade
...askell.org (aka haskell.galois.com; aka monk) is in need of an OS upgrade. It's currently running Debian ''sarge''; the upgrade will be to ''etch'', the before doing the upgrade. Then upgrade postgres (it should migrate the data) and stop the server running to see if anyone compl

3 KB (427 words) - 22:48, 23 April 2021
Parallel/Glossary
: ''TODO: non-Haskellers may have heard of MapReduce - what does it translate to in Haskell terms?'' : A deterministic parallel Haskell library. It provides an API that resembles Concurrent Haskell (without sacrificing pred

4 KB (606 words) - 16:32, 17 April 2014
Metaチュートリアル
: ''and if you say no, it points you at a tutorial which explains it'' -- ndm on #haskell

5 KB (398 words) - 11:37, 22 October 2022
Maybe
It allows the programmer to specify something may not be there. When the module is imported, it supplies a variety of useful functions including:

2 KB (409 words) - 00:28, 11 November 2023
WxAsteroids
and unpack it; go to the directory with the game code ...b/master/reactive-banana-wx/src/Asteroids.hs version of the main program], it uses the package [http://hackage.haskell.org/package/reactive-banana reacti

2 KB (267 words) - 19:22, 21 September 2014
Cont computations as question-answering boxes
...just hang on to a value of type <code>t</code>, and answer questions about it truthfully, by simply applying them to the value. (The fun will happen late ...</code>. That's a bit brain-twisting, so let's think about how we might do it...

7 KB (1,253 words) - 23:34, 25 June 2021
Web/Servers
...rtions of the server are not cleanly separated into different packages, so it is not the best choice if you only need a low-level backend. ...rks#Snap Snap framework], the Snap HTTP server is similar to Hyena in that it provides a very fast low level web server.

5 KB (695 words) - 08:40, 2 July 2017
Failure
* Error usually refers to a programming error. It can also refer to the "error" function, which in fact causes a runtime exce * Exception usually refers to an exception which is thrown in the IO monad. It can also refer to the actual typeclass "Exception" which was introduced alo

6 KB (961 words) - 12:45, 12 August 2019
Hackage
...'' is the Haskell community's central package archive. Package authors use it to publish their libraries and programs while other Haskell programmers use * The main [https://hackage.haskell.org/ web interface]. It also has [https://hackage.haskell.org/api interfaces] used by tools like [[

2 KB (335 words) - 11:22, 25 February 2016
Installing xmonad log applet
...highly experimental application that's seen very little testing. However, it's also small, simple, and unlikely to break other parts of your system. Fro ...space it's possible to build the applet on another host and simply install it on the small device, however that's outside the scope of this discussion.

6 KB (1,036 words) - 10:20, 20 April 2021
SDL/Windows
...ecompiled [https://www.libsdl.org/download-2.0.php SDL2 package] and unzip it to e.g. C:\Libs .... You might be able to get around this restriction with some symlinks, but it's really not worth the effort.

6 KB (984 words) - 23:58, 17 June 2016
CabalFind
...ost frequently a darcs repo) somewhere Google Bot or Yahoo Slurp may index it, and eventually information about your package will show up in search resul It will be necessary to parse the returned HTML for <a> tags containing filena

4 KB (666 words) - 22:21, 23 April 2021
Why not Pointed?
...tually abuses of ad hoc relationships it happens to have for the instances it does offer. The one law Pointed offers is how it interoperates with fmap:

4 KB (765 words) - 04:26, 4 September 2013
Installers
...your enthusiasm and, instead of just putting your own tool first, think of it as adding functionality to a whole box of Haskell tools. You may only chang ...tively replacing all handlers associated with the existing file types; but it would be nice if new installers would try to copy existing handlers before

6 KB (1,025 words) - 20:14, 9 December 2020
XMonadContribTour
...r for new users, but applied to the XMonad Contrib. Mainly because I think it's very difficult for newcomers to discover what extra features XMonad provi ...-docs/xmonad-contrib/XMonad-Hooks-DynamicLog.html XMonad.Hooks.DynamicLog] it provides some drop-in loggers and some helper functions to make your own lo

7 KB (1,099 words) - 15:18, 6 February 2021
MigratingWikiContent
...ror, so does uploading of new PDF files. The wiki admins are looking into it. ...t other markup inside <hask> or <haskell> tags. You can may rewrite it to use no syntax highlighting (using <code>) or perhaps use Unicode symb

1 KB (234 words) - 05:13, 24 April 2021
Monad laws
It's now easy to see that monad composition is an associative operator with le When we see a program written in a form on the left-hand side, we expect it to do the same thing as the corresponding right-hand side; and vice versa.

5 KB (788 words) - 10:40, 1 February 2024
Concurrency with oracles
...ith concurrency presents a challenge - the usual techniques for supporting it used by most other (imperative) languages cannot not be simply transferred ...am should depend on the order in which external events occur. For example, it might be desirable to merge the elements of two lists in the order in which

4 KB (565 words) - 06:24, 12 June 2023
Xmonad/Notable changes since 0.7
...e of XMonad.Layout.WindowNavigation that lets you navigate across screens. It has some bugs. ...rompt), and the URL string. If you want to replicate the old simpleEngine, it'd look like 'newEngine = searchEngine "" "http://..."'.

3 KB (451 words) - 12:13, 19 April 2021
Nitpicks
...s probably not important enough to justify the added complexity of tacking it on as an extension or breaking existing code. ...go back in time and fix it before it happened, we probably would, but now it would probably be too onerous.

7 KB (1,033 words) - 01:16, 27 September 2021
Extensible datatypes
...e this can be done with <tt>Dynamic</tt> too, by defining dummy types. But it's ugly. It's possible to define [[Dynamic]] using extensible datatypes. Here's a naive

4 KB (587 words) - 11:16, 28 March 2018
Scrap your boilerplate
In the current GHC implementation, it consists of a set of modules (Data.Generics and its submodules) and derivin ...n alternative to recursive list concatenation - the latter is inefficient. It also illustrates how laziness automatically means that sublists of type [b]

3 KB (427 words) - 01:33, 28 December 2013
Yampa/reactimate
...nuous time but to evaluate a signal function (or a signal for that matter) it is necessary to sample the signals at discrete points in time. This is exac * The <code>init</code> action is rather self-explanatory; it executes an initial IO action (e.g. print a welcome message), which then yi

5 KB (780 words) - 11:40, 6 June 2016
Partial application
...ng <hask>add</hask>. It is a new function that takes an integer, adds 1 to it and returns that as the result.

1 KB (248 words) - 20:05, 13 May 2020
DDC/EffectSystem
In Haskell, because <hask>putStr</hask> prints to the screen it has the <hask>IO</hask> constructor in its return type: But wait, that's evil isn't it?

5 KB (834 words) - 04:20, 8 June 2023
Salsa
It uses type families extensively to provide a type-safe mapping of the .NET ...ypographical error can trigger multiple pages of errors from GHC, or cause it to eat lots of memory.

5 KB (685 words) - 07:56, 22 August 2016
Diagrams/Dev/Gradients
...actually ''above'' the g transform node in the tree, but it seems perhaps it is actually looking at any path nodes which actually use the fill, although ...rmation (an 'M' node) instead of a split (:|:) and the only way to tell if it is frozen is to look for any splits below

9 KB (1,383 words) - 16:48, 18 November 2013

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