https://wiki.haskell.org/api.php?action=feedcontributions&user=SergeyAstanin&feedformat=atomHaskellWiki - User contributions [en]2022-09-30T09:56:15ZUser contributionsMediaWiki 1.31.7https://wiki.haskell.org/index.php?title=Applications_and_libraries/Mathematics&diff=55738Applications and libraries/Mathematics2013-04-23T10:07:40Z<p>SergeyAstanin: /* Linear algebra */</p>
<hr />
<div>== Applications ==<br />
<br />
=== Physics ===<br />
<br />
;[http://ab-initio.mit.edu/meep/ Meep]<br />
:Meep (or MEEP) is a free finite-difference time-domain (FDTD) simulation software package developed at MIT to model electromagnetic systems.<br />
<br />
;[[Numeric Quest]]<br />
:Jan Skibinski's [[Numeric Quest]] library provides modules that are useful for Quantum Mechanics, among other things.<br />
<br />
== Libraries ==<br />
<br />
=== Linear algebra ===<br />
<br />
;[https://github.com/patperry/hs-linear-algebra hs-linear-algebra]<br />
:Patrick Perry's linear algebra library, built on BLAS. [https://github.com/cartazio/hs-cblas hs-cblas] seems to be a more up-to-date fork.<br />
<br />
;[http://www.cs.utah.edu/~hal/HBlas/index.html Wrapper to CLAPACK]<br />
<br />
;[http://haskelldsp.sourceforge.net/ Digital Signal Processing]<br />
:Modules for matrix manipulation, Fourier transform, interpolation, spectral estimation, and frequency estimation.<br />
<br />
;[http://article.gmane.org/gmane.comp.lang.haskell.general/13561 Index-aware linear algebra]<br />
:Frederik Eaton's library for statically checked matrix manipulation in Haskell<br />
<br />
;[[Numeric Quest]]<br />
:Jan Skibinski's [[Numeric Quest]] library provides several modules that are useful for linear algebra in general, among other things.<br />
<br />
;[[vector-space]]<br />
:The [[vector-space]] package defines classes and generic operations for vector spaces and affine spaces. It also defines a type of infinite towers of generalized derivatives (linear transformations).<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hmatrix HMatrix]<br />
:By Alberto Ruiz. From the project [http://perception.inf.um.es/hmatrix/ website]:<br />
::''A purely functional interface to linear algebra and other numerical algorithms, internally implemented using LAPACK, BLAS, and GSL.<br />
<br />
::''This package includes standard matrix decompositions (eigensystems, singular values, Cholesky, QR, etc.), linear systems, numeric integration, root finding, etc.<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Vec Vec]<br />
:By Scott E. Dillard. Static dimension checking:<br />
::''Vectors are represented by lists with type-encoded lengths. The constructor is :., which acts like a cons both at the value and type levels, with () taking the place of nil. So x:.y:.z:.() is a 3d vector. The library provides a set of common list-like functions (map, fold, etc) for working with vectors. Built up from these functions are a small but useful set of linear algebra operations: matrix multiplication, determinants, solving linear systems, inverting matrices.''<br />
<br />
== See also ==<br />
<br />
* [[Linear algebra]]<br />
* [[Mathematical prelude discussion]]<br />
<br />
<br />
See also: [[Linear algebra|Design discussions]]<br />
<br />
=== [[Physical units]] ===<br />
<br />
;[[Dimensionalized numbers]]<br />
: Working with physical units like second, meter and so on in a type-safe manner.<br />
<br />
;[http://darcs.haskell.org/numericprelude/src/Number/SI.hs NumericPrelude: Physical units]<br />
: Numeric values with dynamically checked units.<br />
<br />
;[[CalDims]]<br />
:This is not simply a library providing a new type of <hask>Num</hask> class, but stand-alone calculation tool that supports user defined functions and units (basic and derived), so it can provide dimension-safe calculation (not embedded but via shell). Calculations can be modified/saved via shell. It uses rational numbers to avoid rounding errors where possible.<br />
<br />
;[http://code.google.com/p/dimensional/ Dimensional]<br />
: Library providing data types for performing arithmetic with physical quantities and units. Information about the physical dimensions of the quantities/units is embedded in their types and the validity of operations is verified by the type checker at compile time. The boxing and unboxing of numerical values as quantities is done by multiplication and division of units.<br />
<br />
=== Number representations ===<br />
<br />
==== Decimal numbers ====<br />
<br />
;[http://src.seereason.com/decimal/ Decimal arithmetic library]<br />
:An implementation of real decimal arithmetic, for cases where the binary floating point is not acceptable (for example, money).<br />
<br />
==== Real and rational numbers ====<br />
<br />
There are several levels of [[Exact real arithmetic|handling real numbers]] and according libraries.<br />
<br />
===== Arbitrary precision =====<br />
<br />
* Numbers have fixed precision<br />
* Rounding errors accumulate<br />
* Sharing is easy, i.e. in <hask>sqrt pi + sin pi</hask>, <hask>pi</hask> is computed only once<br />
* Fast, because the routines can make use of the fast implementation of <hask>Integer</hask> operations<br />
<br />
;[[Numeric Quest]]<br />
:Jan Skibinski's [[Numeric Quest]] library provides, among other things, a type for arbitrary precision rational numbers with transcendental functions.<br />
<br />
;[http://cvs.haskell.org/darcs/numericprelude/src/Number/FixedPoint.hs FixedPoint.hs]<br />
:part of NumericPrelude project<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/AERN-Basics AERN-Basics] [http://hackage.haskell.org/cgi-bin/hackage-scripts/package/AERN-Real AERN-Real] [http://hackage.haskell.org/cgi-bin/hackage-scripts/package/AERN-Real-Interval AERN-Real-Interval] [http://hackage.haskell.org/cgi-bin/hackage-scripts/package/AERN-Real-Double AERN-Real-Double]<br />
:contains type classes that form a foundation for ''rounded arithmetic'' and ''interval arithmetic'' with explicit control of rounding and the possibility to increase the rounding precision arbitrarily for types that support it. At the moment there are instances for Double floating point numbers where one can control the direction of rounding but cannot increase the rounding precision. In the near future instances for MPFR arbitrary precision numbers will be provided. Intervals can use as endpoints any type that supports directed rounding in the numerical order (such as Double or MPFR) and operations on intervals are rounded either outwards or inwards. Outwards rounding allows to safely approximate exact real arithmetic while a combination of both outwards and inwards rounding allows one to safely approximate exact interval arithmetic. Inverted intervals with Kaucher arithmetic are also supported.<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/AERN-RnToRm AERN-RnToRm]<br />
:contains arithmetic of ''piecewise polynomial function intervals'' that approximate multi-dimensional (almost everywhere) continuous real functions to arbitrary precision<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hmpfr hmpfr]<br />
:hmpfr is a purely functional haskell interface to the [http://www.mpfr.org/ MPFR] library<br />
<br />
;[http://hackage.haskell.org/package/numbers numbers]<br />
:provides an up-to-date, easy-to-use BigFloat implementation that builds with a modern GHC, among other things.<br />
<br />
===== Dynamic precision =====<br />
<br />
* You tell the precision and an expression shall be computed to, and the computer finds out, how precisely to compute the input values<br />
* Rounding errors do not accumulate<br />
* Sharing of temporary results is difficult, that is, in <hask>sqrt pi + sin pi</hask>, <hask>pi</hask> ''will'' be computed twice, each time with the required precision.<br />
* Almost as fast as arbitrary precision computation<br />
<br />
;[http://www.cs.man.ac.uk/arch/dlester/exact.html ERA] is an implementation (in Haskell 1.2) by David Lester.<br />
: It is quite fast, possibly the fastest Haskell implementation. At 220 lines it is also the shortest. Probably the shortest implementation of exact real arithmetic in any language.<br />
: The provided number type <hask>CReal</hask> is instance of the Haskell 98 numeric type classes and thus can be used whereever you used Float or Double before and encountered some numerical difficulties.<br />
:Here is a mirror: http://darcs.augustsson.net/Darcs/CReal/<br />
<br />
;[http://www.doc.ic.ac.uk/~ae/exact-computation/#bm:implementations IC-Reals] is an implementation by Abbas Edalat, Marko Krznar&#263; and Peter J. Potts.<br />
:This implementation uses linear fractional transformations.<br />
<br />
;[http://r6.ca/ Few Digits] by Russell O'Connor.<br />
:This is a prototype of the implementation he intendeds to write in [http://coq.inria.fr/ Coq]. Once the Coq implementation is complete, the Haskell code could be extracted producing an implementation that would be proved correct.<br />
<!--<br />
Example:<br />
*Data.Real.CReal> answer 1000 (exp 1 + sqrt 2)<br />
--><br />
<br />
;COMP is an implementation by Yann Kieffer.<br />
:The work is in beta and relies on new primitive operations on Integers which will be implemented in GHC. The library isn't available yet.<br />
<br />
;[http://www2.arnes.si/~abizja4/hera/ Hera] is an implementation by Aleš Bizjak.<br />
:It uses the [http://www.mpfr.org/ MPFR] library to implement dyadic rationals, on top of which are implemented intervals and real numbers. A real number is represented as a function <hask>Int -> Interval</hask> which represents a sequence of intervals converging to the real.<br />
<br />
===== Dynamic precision by lazy evaluation =====<br />
<br />
The real numbers are represented by an infinite datastructure, which allows you to increase precision successively by evaluating the data structure successively. All of the implementations below use some kind of digit stream as number representation.<br />
Sharing of results is simple.<br />
The implementations are either fast on simple expressions, because they use large blocks/bases, or they are fast on complex expressions, because they consume as little as possible input digits in order to emit the required output digits.<br />
<br />
;[http://medialab.freaknet.org/bignum/ BigFloat] is an implementation by Martin Guy.<br />
:It works with streams of decimal digits (strictly in the range from 0 to 9) and a separate sign. The produced digits are always correct. Output is postponed until the code is certain what the next digit is. This sometimes means that [http://medialab.freaknet.org/bignum/dudeney.html no more data is output].<br />
<br />
;In [http://users.info.unicaen.fr/~karczma/arpap/lazypi.ps.gz "The Most Unreliable Technique in the World to compute pi"] Jerzy Karczmarczuk develops some functions for computing pi lazily.<br />
<br />
;[http://darcs.haskell.org/numericprelude/src/Number/Positional.hs NumericPrelude: positional numbers]<br />
:Represents a real number as pair <hask>(exponent,[digit])</hask>, where the digits are <hask>Int</hask>s in the open range <hask>(-basis,basis)</hask>. There is no need for an extra sign item in the number data structure. The <hask>basis</hask> can range from <hask>10</hask> to <hask>1000</hask>. (Binary representations can be derived from the hexadecimal representation.) Showing the numbers in traditional format (non-negative digits) fails for fractions ending with a run of zeros. However the internal representation with negative digits can always be shown and is probably more useful for further processing. An interface for the numeric type hierarchy of the NumericPrelude project is provided.<br />
:It features<br />
:* basis conversion<br />
:* basic arithmetic: addition, subtraction, multiplication, division<br />
:* algebraic arithmetic: square root, other roots (no general polynomial roots)<br />
:* transcendental arithmetic: pi, exponential, logarithm, trigonometric and inverse trigonometric functions<br />
<br />
=== Type class hierarchies ===<br />
<br />
There are several approaches to improve the [[Mathematical prelude discussion|numeric type class hierarchy]].<br />
<br />
;Dylan Thurston and Henning Thielemann's [[Numeric Prelude]]<br />
:Experimental revised framework for numeric type classes. Needs hiding of Prelude, overriding hidden functions like fromInteger and multi-parameter type classes. Probably restricted to GHC.<br />
<br />
;Jerzy Karczmarczuk's [http://www.haskell.org/pipermail/haskell-cafe/2001-February/001510.html approach]<br />
<br />
;Serge D. Mechveliani's [ftp://ftp.botik.ru/pub/local/Mechveliani/basAlgPropos/ Basic Algebra proposal]<br />
<br />
;Andrew Frank's [http://www.haskell.org/pipermail/haskell-cafe/2006-April/015326.html approach]<br />
:The proposal: ftp://ftp.geoinfo.tuwien.ac.at/frank/numbersPrelude_v1.pdf<br />
<br />
;Haskell Prime: [http://hackage.haskell.org/trac/haskell-prime/ticket/112 Ongoing efforts for the language revision]<br />
<br />
=== Discrete mathematics ===<br />
<br />
;[http://andrew.bromage.org/darcs/numbertheory/ Number Theory Library]<br />
:Andrew Bromage's Haskell number theory library, providing operations on primes, fibonacci sequences and combinatorics.<br />
<br />
;[http://users.skynet.be/jyp/HGAL/ HGAL]<br />
:An haskell implementation of Brendan McKay's algorithm for graph canonic labeling and automorphism group. (aka Nauty)<br />
<br />
;[http://www.cambridge.org/uk/catalogue/catalogue.asp?isbn=0521849306 Computational Oriented Matroids]<br />
:is a book by [http://wwwopt.mathematik.tu-darmstadt.de/~bokowski/ Jürgen G. Bokowski], where he develops Haskell code for Matroid computations.<br />
<br />
See also [[Libraries and tools/Cryptography]]<br />
<br />
=== Computer Algebra ===<br />
<br />
;[http://haskell.org/docon/ DoCon] - Algebraic Domain Constructor<br />
:A library for Algebra, turns GHCi into a kind of Computer Algebra System<br />
<br />
;[http://www.info.unicaen.fr/~karczma/arpap/ Papers by Jerzy Karczmarczuk]<br />
:Some interesting uses of Haskell in mathematics, including [[functional differentiation]], power series, continued fractions.<br />
<br />
;[http://www.robtougher.com/HCAS/ HCAS] by Rob Tougher.<br />
<br />
=== Statistics ===<br />
;[http://www.sftank.net/?q=node/10 hstats]<br />
: Statistical Computing with Haskell<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hmatrix-gsl-stats hmatrix-gsl-stats]<br />
: A binding to the statistics portion of GSL. Works with hmatrix<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hstatistics hstatistics]<br />
: A library for doing statistics. Works with hmatrix<br />
<br />
=== Plotting ===<br />
<br />
;[http://hackage.haskell.org/package/easyplot easyplot]<br />
: Simple and easy wrapper to gnuplot.<br />
<br />
;[[Gnuplot]]<br />
: Simple wrapper to gnuplot<br />
<br />
;[http://alberrto.googlepages.com/gslhaskell GSLHaskell]<br />
: gnuplot wrapper as part of GSL Haskell package<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Chart Chart]<br />
: A library for generating 2D Charts and Plots, based upon the cairo graphics library.<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/plot plot]<br />
: A library for generating figures, based upon the cairo graphics libary with<br />
a simple, monadic interface.<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/probability probability]<br />
: the module Numeric.Probability.Visualize contains a wrapper to [http://www.r-project.org/ R]<br />
<br />
=== Miscellaneous libraries ===<br />
<br />
;[http://www.robtougher.com/HaskellMath/ HaskellMath]<br />
:The HaskellMath library is a sandbox for experimenting with mathematics algorithms. So far I've implemented a few quantitative finance models (Black Scholes, Binomial Trees, etc) and basic linear algebra functions. Next I might work on either computer algebra or linear programming. All comments welcome!<br />
<br />
;[http://hackage.haskell.org/package/HaskellForMaths HaskellForMaths]<br />
:David Amos' library for combinatorics, group theory, commutative algebra and non-commutative algebra, which is described in an [http://haskellformaths.blogspot.com/ accompanying blog].<br />
<br />
;[http://darcs.haskell.org/htam/ Various math stuff by Henning Thielemann]<br />
:This is some unsorted mathematical stuff including: gnuplot wrapper (now maintained as separate package), portable grey map (PGM) image reader and writer, simplest numerical integration, differentiation, zero finding, interpolation, solution of differential equations, combinatorics, some solutions of math riddles, computation of fractal dimensions of iterated function systems (IFS)<br />
<br />
;[[Numeric Quest]]<br />
:Jan Skibinski wrote a collection of Haskell modules that are useful for Mathematics in general, and Quantum Mechanics in particular.<br />
<br />
:Some of the modules are hosted on [http://darcs.haskell.org/numeric-quest/ haskell.org]. They include modules for:<br />
:* Rational numbers with transcendental functions<br />
:* Roots of polynomials<br />
:* Eigensystems<br />
:* Tensors<br />
:* Dirac quantum mechanics<br />
<br />
:Other modules in Numeric Quest are currently only available via the [http://web.archive.org/web/20010605003250/http://www.numeric-quest.com/haskell/ Internet Archive]. They include, among many other things:<br />
:* [http://web.archive.org/web/*/http://www.numeric-quest.com/haskell/ State vector evolution]<br />
:* [http://web.archive.org/web/*/http://www.numeric-quest.com/haskell/ Short study of fuzzy oscillator]<br />
<br />
:See the [[Numeric Quest]] page for more information.<br />
<br />
;[http://www.dinkla.net/fp/cglib.html Geometric Algorithms]<br />
:A small Haskell library, containing algorithms for two-dimensional convex hulls, triangulations of polygons, Voronoi-diagrams and Delaunay-triangulations, the QEDS data structure, kd-trees and range-trees.<br />
<br />
;[http://repetae.net/john/recent/out/HsASA.html Adaptive Simulated Annealing]<br />
:A Haskell interface to Lester Ingber's adaptive simulating annealing code.<br />
<br />
;[http://home.solcon.nl/mklooster/repos/hmm/ Hmm: Haskell Metamath]<br />
:Hmm is a small Haskell library to parse and verify Metamath databases.<br />
<br />
;[[Probabilistic Functional Programming]]<br />
:The PFP library is a collection of modules for Haskell that facilitates probabilistic functional programming, that is, programming with stochastic values. The probabilistic functional programming approach is based on a data type for representing distributions. A distribution represent the outcome of a probabilistic event as a collection of all possible values, tagged with their likelihood. A nice aspect of this system is that simulations can be specified independently from their method of execution. That is, we can either fully simulate or randomize any simulation without altering the code which defines it.<br />
<br />
;[[Sinc function]]<br />
<br />
;[[Gamma and Beta function]]<br />
<br />
;[http://repetae.net/john/recent/out/Boolean.html Boolean]<br />
:A general boolean algebra class and some instances for Haskell.<br />
<br />
;[http://darcs.haskell.org/~lemmih/hode/ HODE]<br />
:HODE is a binding to the Open Dynamics Engine. ODE is an open source, high performance library for simulating rigid body dynamics.<br />
<br />
;[http://sourceforge.net/projects/ranged-sets Ranged Sets]<br />
:A ranged set is a list of non-overlapping ranges. The ranges have upper and lower boundaries, and a boundary divides the base type into values above and below. No value can ever sit on a boundary. So you can have the set <math>(2.0, 3.0] \cup (5.3, 6)</math>.<br />
<br />
;[http://code.google.com/p/hhydra/ hhydra]<br />
:Hhydra is a tool to compute Goodstein successions and hydra puzzles described by Bernard Hodgson in his article 'Herculean or Sisyphean tasks?' published in No 51 March 2004 of the Newsletter of the European Mathematical Society.<br />
<br />
[[Category:Mathematics|*]]<br />
{{LibrariesPage}}</div>SergeyAstaninhttps://wiki.haskell.org/index.php?title=Applications_and_libraries/Mathematics&diff=55737Applications and libraries/Mathematics2013-04-23T10:06:45Z<p>SergeyAstanin: /* Linear algebra */ link to cartazio's fork</p>
<hr />
<div>== Applications ==<br />
<br />
=== Physics ===<br />
<br />
;[http://ab-initio.mit.edu/meep/ Meep]<br />
:Meep (or MEEP) is a free finite-difference time-domain (FDTD) simulation software package developed at MIT to model electromagnetic systems.<br />
<br />
;[[Numeric Quest]]<br />
:Jan Skibinski's [[Numeric Quest]] library provides modules that are useful for Quantum Mechanics, among other things.<br />
<br />
== Libraries ==<br />
<br />
=== Linear algebra ===<br />
<br />
;[https://github.com/patperry/hs-linear-algebra hs-linear-algebra]<br />
:Patrick Perry's linear algebra library, built on BLAS.<br />
[https://github.com/cartazio/hs-cblas hs-cblas] seems to be<br />
a more up-to-date fork of it.<br />
<br />
;[http://www.cs.utah.edu/~hal/HBlas/index.html Wrapper to CLAPACK]<br />
<br />
;[http://haskelldsp.sourceforge.net/ Digital Signal Processing]<br />
:Modules for matrix manipulation, Fourier transform, interpolation, spectral estimation, and frequency estimation.<br />
<br />
;[http://article.gmane.org/gmane.comp.lang.haskell.general/13561 Index-aware linear algebra]<br />
:Frederik Eaton's library for statically checked matrix manipulation in Haskell<br />
<br />
;[[Numeric Quest]]<br />
:Jan Skibinski's [[Numeric Quest]] library provides several modules that are useful for linear algebra in general, among other things.<br />
<br />
;[[vector-space]]<br />
:The [[vector-space]] package defines classes and generic operations for vector spaces and affine spaces. It also defines a type of infinite towers of generalized derivatives (linear transformations).<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hmatrix HMatrix]<br />
:By Alberto Ruiz. From the project [http://perception.inf.um.es/hmatrix/ website]:<br />
::''A purely functional interface to linear algebra and other numerical algorithms, internally implemented using LAPACK, BLAS, and GSL.<br />
<br />
::''This package includes standard matrix decompositions (eigensystems, singular values, Cholesky, QR, etc.), linear systems, numeric integration, root finding, etc.<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Vec Vec]<br />
:By Scott E. Dillard. Static dimension checking:<br />
::''Vectors are represented by lists with type-encoded lengths. The constructor is :., which acts like a cons both at the value and type levels, with () taking the place of nil. So x:.y:.z:.() is a 3d vector. The library provides a set of common list-like functions (map, fold, etc) for working with vectors. Built up from these functions are a small but useful set of linear algebra operations: matrix multiplication, determinants, solving linear systems, inverting matrices.''<br />
<br />
== See also ==<br />
<br />
* [[Linear algebra]]<br />
* [[Mathematical prelude discussion]]<br />
<br />
<br />
See also: [[Linear algebra|Design discussions]]<br />
<br />
=== [[Physical units]] ===<br />
<br />
;[[Dimensionalized numbers]]<br />
: Working with physical units like second, meter and so on in a type-safe manner.<br />
<br />
;[http://darcs.haskell.org/numericprelude/src/Number/SI.hs NumericPrelude: Physical units]<br />
: Numeric values with dynamically checked units.<br />
<br />
;[[CalDims]]<br />
:This is not simply a library providing a new type of <hask>Num</hask> class, but stand-alone calculation tool that supports user defined functions and units (basic and derived), so it can provide dimension-safe calculation (not embedded but via shell). Calculations can be modified/saved via shell. It uses rational numbers to avoid rounding errors where possible.<br />
<br />
;[http://code.google.com/p/dimensional/ Dimensional]<br />
: Library providing data types for performing arithmetic with physical quantities and units. Information about the physical dimensions of the quantities/units is embedded in their types and the validity of operations is verified by the type checker at compile time. The boxing and unboxing of numerical values as quantities is done by multiplication and division of units.<br />
<br />
=== Number representations ===<br />
<br />
==== Decimal numbers ====<br />
<br />
;[http://src.seereason.com/decimal/ Decimal arithmetic library]<br />
:An implementation of real decimal arithmetic, for cases where the binary floating point is not acceptable (for example, money).<br />
<br />
==== Real and rational numbers ====<br />
<br />
There are several levels of [[Exact real arithmetic|handling real numbers]] and according libraries.<br />
<br />
===== Arbitrary precision =====<br />
<br />
* Numbers have fixed precision<br />
* Rounding errors accumulate<br />
* Sharing is easy, i.e. in <hask>sqrt pi + sin pi</hask>, <hask>pi</hask> is computed only once<br />
* Fast, because the routines can make use of the fast implementation of <hask>Integer</hask> operations<br />
<br />
;[[Numeric Quest]]<br />
:Jan Skibinski's [[Numeric Quest]] library provides, among other things, a type for arbitrary precision rational numbers with transcendental functions.<br />
<br />
;[http://cvs.haskell.org/darcs/numericprelude/src/Number/FixedPoint.hs FixedPoint.hs]<br />
:part of NumericPrelude project<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/AERN-Basics AERN-Basics] [http://hackage.haskell.org/cgi-bin/hackage-scripts/package/AERN-Real AERN-Real] [http://hackage.haskell.org/cgi-bin/hackage-scripts/package/AERN-Real-Interval AERN-Real-Interval] [http://hackage.haskell.org/cgi-bin/hackage-scripts/package/AERN-Real-Double AERN-Real-Double]<br />
:contains type classes that form a foundation for ''rounded arithmetic'' and ''interval arithmetic'' with explicit control of rounding and the possibility to increase the rounding precision arbitrarily for types that support it. At the moment there are instances for Double floating point numbers where one can control the direction of rounding but cannot increase the rounding precision. In the near future instances for MPFR arbitrary precision numbers will be provided. Intervals can use as endpoints any type that supports directed rounding in the numerical order (such as Double or MPFR) and operations on intervals are rounded either outwards or inwards. Outwards rounding allows to safely approximate exact real arithmetic while a combination of both outwards and inwards rounding allows one to safely approximate exact interval arithmetic. Inverted intervals with Kaucher arithmetic are also supported.<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/AERN-RnToRm AERN-RnToRm]<br />
:contains arithmetic of ''piecewise polynomial function intervals'' that approximate multi-dimensional (almost everywhere) continuous real functions to arbitrary precision<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hmpfr hmpfr]<br />
:hmpfr is a purely functional haskell interface to the [http://www.mpfr.org/ MPFR] library<br />
<br />
;[http://hackage.haskell.org/package/numbers numbers]<br />
:provides an up-to-date, easy-to-use BigFloat implementation that builds with a modern GHC, among other things.<br />
<br />
===== Dynamic precision =====<br />
<br />
* You tell the precision and an expression shall be computed to, and the computer finds out, how precisely to compute the input values<br />
* Rounding errors do not accumulate<br />
* Sharing of temporary results is difficult, that is, in <hask>sqrt pi + sin pi</hask>, <hask>pi</hask> ''will'' be computed twice, each time with the required precision.<br />
* Almost as fast as arbitrary precision computation<br />
<br />
;[http://www.cs.man.ac.uk/arch/dlester/exact.html ERA] is an implementation (in Haskell 1.2) by David Lester.<br />
: It is quite fast, possibly the fastest Haskell implementation. At 220 lines it is also the shortest. Probably the shortest implementation of exact real arithmetic in any language.<br />
: The provided number type <hask>CReal</hask> is instance of the Haskell 98 numeric type classes and thus can be used whereever you used Float or Double before and encountered some numerical difficulties.<br />
:Here is a mirror: http://darcs.augustsson.net/Darcs/CReal/<br />
<br />
;[http://www.doc.ic.ac.uk/~ae/exact-computation/#bm:implementations IC-Reals] is an implementation by Abbas Edalat, Marko Krznar&#263; and Peter J. Potts.<br />
:This implementation uses linear fractional transformations.<br />
<br />
;[http://r6.ca/ Few Digits] by Russell O'Connor.<br />
:This is a prototype of the implementation he intendeds to write in [http://coq.inria.fr/ Coq]. Once the Coq implementation is complete, the Haskell code could be extracted producing an implementation that would be proved correct.<br />
<!--<br />
Example:<br />
*Data.Real.CReal> answer 1000 (exp 1 + sqrt 2)<br />
--><br />
<br />
;COMP is an implementation by Yann Kieffer.<br />
:The work is in beta and relies on new primitive operations on Integers which will be implemented in GHC. The library isn't available yet.<br />
<br />
;[http://www2.arnes.si/~abizja4/hera/ Hera] is an implementation by Aleš Bizjak.<br />
:It uses the [http://www.mpfr.org/ MPFR] library to implement dyadic rationals, on top of which are implemented intervals and real numbers. A real number is represented as a function <hask>Int -> Interval</hask> which represents a sequence of intervals converging to the real.<br />
<br />
===== Dynamic precision by lazy evaluation =====<br />
<br />
The real numbers are represented by an infinite datastructure, which allows you to increase precision successively by evaluating the data structure successively. All of the implementations below use some kind of digit stream as number representation.<br />
Sharing of results is simple.<br />
The implementations are either fast on simple expressions, because they use large blocks/bases, or they are fast on complex expressions, because they consume as little as possible input digits in order to emit the required output digits.<br />
<br />
;[http://medialab.freaknet.org/bignum/ BigFloat] is an implementation by Martin Guy.<br />
:It works with streams of decimal digits (strictly in the range from 0 to 9) and a separate sign. The produced digits are always correct. Output is postponed until the code is certain what the next digit is. This sometimes means that [http://medialab.freaknet.org/bignum/dudeney.html no more data is output].<br />
<br />
;In [http://users.info.unicaen.fr/~karczma/arpap/lazypi.ps.gz "The Most Unreliable Technique in the World to compute pi"] Jerzy Karczmarczuk develops some functions for computing pi lazily.<br />
<br />
;[http://darcs.haskell.org/numericprelude/src/Number/Positional.hs NumericPrelude: positional numbers]<br />
:Represents a real number as pair <hask>(exponent,[digit])</hask>, where the digits are <hask>Int</hask>s in the open range <hask>(-basis,basis)</hask>. There is no need for an extra sign item in the number data structure. The <hask>basis</hask> can range from <hask>10</hask> to <hask>1000</hask>. (Binary representations can be derived from the hexadecimal representation.) Showing the numbers in traditional format (non-negative digits) fails for fractions ending with a run of zeros. However the internal representation with negative digits can always be shown and is probably more useful for further processing. An interface for the numeric type hierarchy of the NumericPrelude project is provided.<br />
:It features<br />
:* basis conversion<br />
:* basic arithmetic: addition, subtraction, multiplication, division<br />
:* algebraic arithmetic: square root, other roots (no general polynomial roots)<br />
:* transcendental arithmetic: pi, exponential, logarithm, trigonometric and inverse trigonometric functions<br />
<br />
=== Type class hierarchies ===<br />
<br />
There are several approaches to improve the [[Mathematical prelude discussion|numeric type class hierarchy]].<br />
<br />
;Dylan Thurston and Henning Thielemann's [[Numeric Prelude]]<br />
:Experimental revised framework for numeric type classes. Needs hiding of Prelude, overriding hidden functions like fromInteger and multi-parameter type classes. Probably restricted to GHC.<br />
<br />
;Jerzy Karczmarczuk's [http://www.haskell.org/pipermail/haskell-cafe/2001-February/001510.html approach]<br />
<br />
;Serge D. Mechveliani's [ftp://ftp.botik.ru/pub/local/Mechveliani/basAlgPropos/ Basic Algebra proposal]<br />
<br />
;Andrew Frank's [http://www.haskell.org/pipermail/haskell-cafe/2006-April/015326.html approach]<br />
:The proposal: ftp://ftp.geoinfo.tuwien.ac.at/frank/numbersPrelude_v1.pdf<br />
<br />
;Haskell Prime: [http://hackage.haskell.org/trac/haskell-prime/ticket/112 Ongoing efforts for the language revision]<br />
<br />
=== Discrete mathematics ===<br />
<br />
;[http://andrew.bromage.org/darcs/numbertheory/ Number Theory Library]<br />
:Andrew Bromage's Haskell number theory library, providing operations on primes, fibonacci sequences and combinatorics.<br />
<br />
;[http://users.skynet.be/jyp/HGAL/ HGAL]<br />
:An haskell implementation of Brendan McKay's algorithm for graph canonic labeling and automorphism group. (aka Nauty)<br />
<br />
;[http://www.cambridge.org/uk/catalogue/catalogue.asp?isbn=0521849306 Computational Oriented Matroids]<br />
:is a book by [http://wwwopt.mathematik.tu-darmstadt.de/~bokowski/ Jürgen G. Bokowski], where he develops Haskell code for Matroid computations.<br />
<br />
See also [[Libraries and tools/Cryptography]]<br />
<br />
=== Computer Algebra ===<br />
<br />
;[http://haskell.org/docon/ DoCon] - Algebraic Domain Constructor<br />
:A library for Algebra, turns GHCi into a kind of Computer Algebra System<br />
<br />
;[http://www.info.unicaen.fr/~karczma/arpap/ Papers by Jerzy Karczmarczuk]<br />
:Some interesting uses of Haskell in mathematics, including [[functional differentiation]], power series, continued fractions.<br />
<br />
;[http://www.robtougher.com/HCAS/ HCAS] by Rob Tougher.<br />
<br />
=== Statistics ===<br />
;[http://www.sftank.net/?q=node/10 hstats]<br />
: Statistical Computing with Haskell<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hmatrix-gsl-stats hmatrix-gsl-stats]<br />
: A binding to the statistics portion of GSL. Works with hmatrix<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hstatistics hstatistics]<br />
: A library for doing statistics. Works with hmatrix<br />
<br />
=== Plotting ===<br />
<br />
;[http://hackage.haskell.org/package/easyplot easyplot]<br />
: Simple and easy wrapper to gnuplot.<br />
<br />
;[[Gnuplot]]<br />
: Simple wrapper to gnuplot<br />
<br />
;[http://alberrto.googlepages.com/gslhaskell GSLHaskell]<br />
: gnuplot wrapper as part of GSL Haskell package<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Chart Chart]<br />
: A library for generating 2D Charts and Plots, based upon the cairo graphics library.<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/plot plot]<br />
: A library for generating figures, based upon the cairo graphics libary with<br />
a simple, monadic interface.<br />
<br />
;[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/probability probability]<br />
: the module Numeric.Probability.Visualize contains a wrapper to [http://www.r-project.org/ R]<br />
<br />
=== Miscellaneous libraries ===<br />
<br />
;[http://www.robtougher.com/HaskellMath/ HaskellMath]<br />
:The HaskellMath library is a sandbox for experimenting with mathematics algorithms. So far I've implemented a few quantitative finance models (Black Scholes, Binomial Trees, etc) and basic linear algebra functions. Next I might work on either computer algebra or linear programming. All comments welcome!<br />
<br />
;[http://hackage.haskell.org/package/HaskellForMaths HaskellForMaths]<br />
:David Amos' library for combinatorics, group theory, commutative algebra and non-commutative algebra, which is described in an [http://haskellformaths.blogspot.com/ accompanying blog].<br />
<br />
;[http://darcs.haskell.org/htam/ Various math stuff by Henning Thielemann]<br />
:This is some unsorted mathematical stuff including: gnuplot wrapper (now maintained as separate package), portable grey map (PGM) image reader and writer, simplest numerical integration, differentiation, zero finding, interpolation, solution of differential equations, combinatorics, some solutions of math riddles, computation of fractal dimensions of iterated function systems (IFS)<br />
<br />
;[[Numeric Quest]]<br />
:Jan Skibinski wrote a collection of Haskell modules that are useful for Mathematics in general, and Quantum Mechanics in particular.<br />
<br />
:Some of the modules are hosted on [http://darcs.haskell.org/numeric-quest/ haskell.org]. They include modules for:<br />
:* Rational numbers with transcendental functions<br />
:* Roots of polynomials<br />
:* Eigensystems<br />
:* Tensors<br />
:* Dirac quantum mechanics<br />
<br />
:Other modules in Numeric Quest are currently only available via the [http://web.archive.org/web/20010605003250/http://www.numeric-quest.com/haskell/ Internet Archive]. They include, among many other things:<br />
:* [http://web.archive.org/web/*/http://www.numeric-quest.com/haskell/ State vector evolution]<br />
:* [http://web.archive.org/web/*/http://www.numeric-quest.com/haskell/ Short study of fuzzy oscillator]<br />
<br />
:See the [[Numeric Quest]] page for more information.<br />
<br />
;[http://www.dinkla.net/fp/cglib.html Geometric Algorithms]<br />
:A small Haskell library, containing algorithms for two-dimensional convex hulls, triangulations of polygons, Voronoi-diagrams and Delaunay-triangulations, the QEDS data structure, kd-trees and range-trees.<br />
<br />
;[http://repetae.net/john/recent/out/HsASA.html Adaptive Simulated Annealing]<br />
:A Haskell interface to Lester Ingber's adaptive simulating annealing code.<br />
<br />
;[http://home.solcon.nl/mklooster/repos/hmm/ Hmm: Haskell Metamath]<br />
:Hmm is a small Haskell library to parse and verify Metamath databases.<br />
<br />
;[[Probabilistic Functional Programming]]<br />
:The PFP library is a collection of modules for Haskell that facilitates probabilistic functional programming, that is, programming with stochastic values. The probabilistic functional programming approach is based on a data type for representing distributions. A distribution represent the outcome of a probabilistic event as a collection of all possible values, tagged with their likelihood. A nice aspect of this system is that simulations can be specified independently from their method of execution. That is, we can either fully simulate or randomize any simulation without altering the code which defines it.<br />
<br />
;[[Sinc function]]<br />
<br />
;[[Gamma and Beta function]]<br />
<br />
;[http://repetae.net/john/recent/out/Boolean.html Boolean]<br />
:A general boolean algebra class and some instances for Haskell.<br />
<br />
;[http://darcs.haskell.org/~lemmih/hode/ HODE]<br />
:HODE is a binding to the Open Dynamics Engine. ODE is an open source, high performance library for simulating rigid body dynamics.<br />
<br />
;[http://sourceforge.net/projects/ranged-sets Ranged Sets]<br />
:A ranged set is a list of non-overlapping ranges. The ranges have upper and lower boundaries, and a boundary divides the base type into values above and below. No value can ever sit on a boundary. So you can have the set <math>(2.0, 3.0] \cup (5.3, 6)</math>.<br />
<br />
;[http://code.google.com/p/hhydra/ hhydra]<br />
:Hhydra is a tool to compute Goodstein successions and hydra puzzles described by Bernard Hodgson in his article 'Herculean or Sisyphean tasks?' published in No 51 March 2004 of the Newsletter of the European Mathematical Society.<br />
<br />
[[Category:Mathematics|*]]<br />
{{LibrariesPage}}</div>SergeyAstaninhttps://wiki.haskell.org/index.php?title=Functional_Reactive_Programming&diff=34701Functional Reactive Programming2010-05-11T15:52:22Z<p>SergeyAstanin: added WxFruit</p>
<hr />
<div>Functional Reactive Programming (FRP) integrates time flow and compositional events into functional programming. This provides an elegant way to express computation in domains such as interactive animations, robotics, computer vision, user interfaces, and simulation.<br />
<br />
== Libraries ==<br />
* [http://conal.net/fran/ Fran]<br />
* [[Grapefruit]]<br />
* [[Reactive]]<br />
* [[DataDriven]]<br />
* [[Yampa]]<br />
* [[WxFruit]]<br />
<br />
== Material ==<br />
* [http://conal.net/papers Conal Elliott’s papers] (several about FRP)<br />
* [[Grapefruit#Publications and talks|Grapefruit-related publications and talks]]<br />
* [http://www.haskell.org/yale/publications.html The Yale Haskell group’s latest publications] (mostly related to FRP)<br />
<br />
== People ==<br />
* [http://www.apocalypse.org/pub/u/antony/work/index.html Antony Courtney]<br />
* [http://conal.net/ Conal Elliott]<br />
* [http://www.ittc.ku.edu/~andygill Andy Gill]<br />
* Liwen Huang<br />
* Paul Hudak<br />
* Wolfgang Jeltsch<br />
* [http://www.cs.nott.ac.uk/~nhn/ Henrik Nilsson]<br />
* [http://mcis.western.edu/~jpeterson/ John Peterson]<br />
<br />
== Blog articles ==<br />
* [http://lukepalmer.wordpress.com/2008/11/28/relative-time-frp/ Relative time FRP]<br />
* Several on [http://conal.net/blog Conal's blog]</div>SergeyAstaninhttps://wiki.haskell.org/index.php?title=ZuriHac2010/Accommodations&diff=34162ZuriHac2010/Accommodations2010-03-18T22:44:00Z<p>SergeyAstanin: </p>
<hr />
<div>This is the accomodation page for [[ZuriHac]]. Please refer to the [[ZuriHac|main page]] for more information.<br />
<br />
Please use this page to organize where you are going to stay.<br />
<br />
{| class="wikitable"<br />
! Names<br />
! Staying At<br />
! Further Information<br />
|-<br />
| Joachim Breitner, Martin Kiefel<br />
| City Backpacker<br />
| Looking for up to four people to share a room.<br />
|- <br />
| Roman Cheplyaka<br />
| City Backpacker<br />
| Room 204<br />
|- <br />
| Jasper Van der Jeugt<br />
| City Backpacker<br />
| Room 404<br />
|-<br />
| Benedikt Huber, David Markvica<br />
| City Backpacker<br />
| Room 201<br />
|-<br />
| Sergey Astanin<br />
| City Backpacker<br />
|<br />
|}</div>SergeyAstaninhttps://wiki.haskell.org/index.php?title=ZuriHac2010/Attendees&diff=33404ZuriHac2010/Attendees2010-01-31T18:14:53Z<p>SergeyAstanin: added myself</p>
<hr />
<div>This is the attendee list for [[ZuriHac]]. Please refer to the [[ZuriHac|main page]] for more information.<br />
<br />
= Attendees =<br />
<br />
Once you've [[ZuriHac/Register|registered]], please add your name to the following table:<br />
<br />
{| class="wikitable"<br />
! Nickname<br />
! Real Name<br />
! Affiliation<br />
! Mobile #<br />
! Arriving<br />
! Departing<br />
! Accomodation<br />
|-<br />
| coeus<br />
| Marc A. Ziegert<br />
| University of Paderborn<br />
| +49 17 5 6000 700<br />
| <br />
| <br />
| <br />
|-<br />
| Heffalump<br />
| Ganesh Sittampalam<br />
| Credit Suisse (Darcs)<br />
| +447968253467<br />
| <br />
| <br />
| <br />
|-<br />
| tibbe<br />
| Johan Tibell<br />
| Google<br />
| +41787978230<br />
| <br />
| <br />
| <br />
|-<br />
| <br />
| Keith Lomax<br />
| <br />
| <br />
| <br />
| <br />
| <br />
|-<br />
| sioraiocht<br />
| Tom Harper<br />
| Oxford University Computing Laboratory<br />
| +44 7533 998 591<br />
|<br />
|<br />
|<br />
|-<br />
| poucet<br />
| Christophe Poucet<br />
| Google<br />
| +41796691013<br />
| <br />
| <br />
| <br />
|-<br />
| zeuxis<br />
| Harald Holtmann<br />
| <br />
| +49 176 22053266<br />
| <br />
| <br />
| <br />
|-<br />
| rmies<br />
| Michel Rijnders<br />
| TTY (Amsterdam)<br />
| +31646442127<br />
|<br />
|<br />
|<br />
|-<br />
| <br />
| Simon Meier<br />
| ETH Zurich<br />
| <br />
|<br />
|<br />
|<br />
|-<br />
| Gh_<br />
| Guillaume Hoffmann<br />
| (Darcs)<br />
|<br />
| 19 morning<br />
| 21 afternoon<br />
|<br />
|-<br />
| vvv<br />
| Valery V. Vorotyntsev<br />
| Infopulse Ukraine<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
| jnwhiteh<br />
| Jim Whitehead<br />
| Oxford University Computing Laboratory<br />
| +44 7846 257 133<br />
| <br />
|<br />
| <br />
|-<br />
| kolmodin<br />
| Lennart Kolmodin<br />
| Västra Götalandsregionen<br />
| +46 73 6223606<br />
| <br />
|<br />
| <br />
|-<br />
| madhadron<br />
| Frederick Ross<br />
| Ecole Polytechnique Federale de Lausanne<br />
| +41 79 710 02 11<br />
| <br />
|<br />
|<br />
|-<br />
| al-maisan<br />
| Muharem Hrnjadovic<br />
| <br />
| +49 (1577) 470-3749<br />
|19 morning<br />
|21 afternoon<br />
|Hotel Neufeld, Friesenbergstraße 15<br />
|-<br />
| beschmi<br />
| Benedikt Schmidt<br />
| ETH Zurich (Darcs)<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
| chr1s<br />
| Chris Eidhof<br />
| Tupil / Utrecht University<br />
| +31628887656<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
| Martijn van Steenbergen<br />
| Utrecht University<br />
| <br />
|<br />
|<br />
|<br />
|-<br />
| hesselink<br />
| Erik Hesselink<br />
| typLAB<br />
| +31650994887<br />
|<br />
|<br />
|<br />
|-<br />
| sfvisser<br />
| Sebastiaan Visser<br />
| typLAB / Utrecht University<br />
| +31624828951<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
| Tom Lokhorst<br />
| Utrecht University<br />
| <br />
|<br />
|<br />
|<br />
|-<br />
| kosmikus<br />
| Andres L&ouml;h<br />
| Utrecht University<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
| smurfpje<br />
| Clara L&ouml;h<br />
| Universit&auml;t G&ouml;ttingen<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
| nomeata<br />
| Joachim Breitner<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
| kowey<br />
| Eric Kow<br />
| University of Brighton (Darcs)<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
| Simon Hengel<br />
| Spin AG<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
| Dirk Spöri<br />
| factis research GmbH<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
| Harald Fischer<br />
| factis research GmbH<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
| Johannes Weiss<br />
| factis research GmbH<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
| Gero Kriependorf<br />
| factis research GmbH<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
| Stefan Wehr<br />
| factis research GmbH<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
| David Leuschner<br />
| factis research GmbH<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
| Steven Keuchel<br />
| Utrecht University<br />
| +31644053336<br />
|<br />
|<br />
|<br />
|-<br />
| dcoutts<br />
| Duncan Coutts<br />
| Well-Typed LLP<br />
| <br />
| <br />
| <br />
|<br />
|-<br />
| tux_rocker<br />
| Reinier Lamers<br />
| (Darcs)<br />
|<br />
| 18 night<br />
| 21 night<br />
|<br />
|-<br />
| jutaro<br />
| Jürgen Nicklisch-Franken<br />
| ICS AG<br />
| <br />
| <br />
|<br />
|<br />
|-<br />
| dons<br />
| Don Stewart<br />
| Galois, Inc<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
| gal_bolle<br />
| Florent Becker<br />
| Université d'Orléans (Darcs)<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
| ErrGe<br />
| Gergely Risko<br />
| Nokia<br />
| +358504899477<br />
| 19 noon<br />
| 22 noon<br />
|<br />
|-<br />
| HugoDaniel<br />
| Hugo Daniel<br />
| New University of Lisbon (UNL)<br />
| <br />
| 18 night<br />
| 22 morning<br />
|<br />
|-<br />
| <br />
| Atze Dijkstra<br />
| Utrecht University<br />
| <br />
| <br />
|<br />
| <br />
|-<br />
| <br />
| Petr Rockai<br />
| (Darcs)<br />
| <br />
| <br />
| <br />
|<br />
|-<br />
| <br />
| Nikolas Mayr<br />
| University of Paderborn<br />
| +49 170 5448278<br />
| 19 morning<br />
| 21 afternoon<br />
|<br />
|-<br />
|<br />
| Sergey Astanin<br />
| Politecnico di Torino<br />
| +39 333 952 0878<br />
|<br />
|<br />
| <br />
|}<br />
<br />
= Additional Comments =<br />
<br />
Please use this section to leave comments for other attendees, e.g. for organizing accommodation.</div>SergeyAstaninhttps://wiki.haskell.org/index.php?title=Hackage_wiki_page_per_project_discussion&diff=32547Hackage wiki page per project discussion2009-12-14T15:32:25Z<p>SergeyAstanin: opt-out when there is a project web page, a bugtracker or a wiki already</p>
<hr />
<div>== Purpose of this page ? ==<br />
collect thoughts about whether we should provide a wiki page (and maybe even more advanced features such as bug trackers) for all projects hosted on hackage<br />
<br />
I'll post a link to this page to haskell-cafe so everyone should participate<br />
<br />
== Why a Wiki ==<br />
We do have about 1500 packages on hackage. Hackage was made life easier.<br />
While packaging some packages for nix (using [[Hack-Nix]]) I had to write some patches.<br />
<br />
If you have a patch what to do?<br />
Duncan Coutts proposed contacting the maintainer. If you don't receive replies within a time frame write to the haskell-cafe mailinglist. If you can't find him become the new maintainer.<br />
<br />
While contacting the maintainer works very well within 3 days in most cases there are situations where maintainers can't reply because they are on holiday or got very busy.. In these cases I'd like to put my patch somewhere so that others can find them.<br />
<br />
== What could a wiki page be used for? ==<br />
<br />
<br />
a) patches (which are removed when maintainers integrate them upstream)<br />
<br />
b) Howtos and pitfalls (written by users or maintainers)<br />
<br />
c) references to similar projects pointing out differences.<br />
<br />
d) a smart lazy changelog. If a user hits a change he can add this to the<br />
wiki so that others can find out faster which version constraints to<br />
add to their .cabal file.<br />
<br />
This looks like this:<br />
2.20: renamed foo to bar.<br />
<br />
2.48: type change of iwillneverChange :: Int to Maybe Int<br />
<br />
e) a list of changes which will go into the next release of a package.<br />
This may help you figuring out whether you should download the darcs repository.<br />
<br />
f) many other ideas I can't think about yet.<br />
<br />
...<br />
<br />
<br />
== implementation details: ==<br />
<br />
design could look like this:<br />
http://mawercer.de/~marc/hackage-link-example.jpg<br />
<br />
The link would point to the haskell wiki having the url suffix /project-name.<br />
<br />
== When a wiki page can replace a .cabal file update ==<br />
<br />
* naturally it takes some time until most recent cabal updates are used by mainstream.. Eg there is a way to add repository locations now.. But have a look at [http://hackage.haskell.org/packages/archive/happy/1.18.4/happy.cabal happy.cabal] and smile :) Btw: I adopted this usage of the source-repository field for one project.<br />
<br />
* minor dependency changes<br />
<br />
* tell users about experimental branches<br />
<br />
* it's easier to provide important information such as:<br />
<br />
"This package is superseded by XY because: ..."<br />
<br />
** We already have a mechanism to deprecate packages or to mark them as superseded. --[[User:DuncanCoutts|DuncanCoutts]] 00:25, 12 December 2009 (UTC)<br />
<br />
[[User:MarcWeber|Marc Weber]]: Can you explain how this works or point me to the documentation?<br />
<br />
The main point about this wiki idea is that you can attach arbitrary information and you don't have to wait for anyone to do so.<br />
Get things done. Provide patches. Link them on the wiki.<br />
Come back later and discuss your proposals with the maintainer.<br />
Keep summaries of discussions on subjects accessible by everyone.<br />
...<br />
<br />
Of course I know that the maintainers are the people doing the real work.<br />
But look at it from a different view: Having such a forum for all projects by default also means that a maintainer can let others do some of the work knowing that they don't have to reply within some days.<br />
<br />
The wiki can host all information which may be useful but which wasn't foreseen by hackage or cabal devs. We must keep agile and move forward only.<br />
<br />
== Concerns ==<br />
<br />
My (DuncanCoutts) concern is about the consent from package authors. Hackage is a social bargain. We ask package authors to distribute their work through hackage because it provides benefits to the community. If we impose too much on package authors then they may decide it's just not worth it.<br />
<br />
In particular, if we automatically create a wiki page for every package then we are imposing additional obligations on package authors. As a package author I might be concerned that this wiki page duplicates an existing home page or bug tracking system. If there's a wiki page about my project then I am effectively obligated to check it from time to time, since users will inevitably report bugs etc there. It is that extra obligation that package authors may resent.<br />
<br />
There is no problem with such a feature being opt-in, but whether it is something we require and impose on package authors needs much more of a social consensus before we go ahead.<br />
<br />
Reply [[User:MarcWeber|Marc Weber]]: Everybody knows that it is wiki content and will take care.<br />
<br />
About effort: Note that package authors can watch their wiki pages easily.<br />
Authors and maintainers already do the hard work. Watching a wiki page is not mach work compared to writing a library. But they may find wiki contents of foreign projects that useful that they provide some contents their selves<br />
<br />
The above concerns amount to saying that there is (or may be) no value added for the user but nevertheless makes extra work for the maintainer. My (Daniel Wagner) concern is that there may actually be value ''removed'' for the user. A bad, incomplete, or non-existent wiki page can be worse than no page at all, because new users may view the wiki page as the canonical resource. This is especially so because many of the smaller projects have minimal or non-existent homepages (often just the root of a darcs repository) and minimal or non-existent documentation; this puts users in the habit of searching elsewhere for information about using the package. Maintainers that do end up putting effort into their project's pages and documentation will suffer as a result, especially if the projects are too small to garner many wiki-editing users. In this case, an unhelpful wiki page may scare away potential users, despite the existence of other useful resources.<br />
<br />
== concern "The wiki will be outdated" ==<br />
True. Every user must know that wikis naturally are out of date :)<br />
But the question is: Can one wiki page (containing an example)<br />
generate more value than some outdated pages cause damage to you?<br />
<br />
It's hard to say because haskellwiki wiki pages can be found when searching from the start page as well.<br />
<br />
Maybe we can ask users to add the package version so that users will see themselves that content is outdated?<br />
<br />
<br />
Don't think about other people. Think about yourself: Do you mind reading some outdated wiki pages? Do you appreciate the valuable contents which will be exist as well? If you don't mind reading some outdated pages and if you'd like to see more examples about how to use packages you basically support this idea!<br />
Let's not forget that haskell.org is a wiki itself. And naturally parts are outdated as well. You still don't want to miss it, do you?<br />
<br />
== wiki alternatives ==<br />
If content isn't put on a wiki what do people do instead?<br />
* They may do nothing (bad)<br />
* They may write a blog (bad because others don't find it or because content gets out of date). Which way is more likely providing you with valuable information: A blog found by google or an attached wiki page people can keep up to date?<br />
* They may write to the mailinglist. Things are archived forever. On the wiki they are as well but not only a small amount of visitors ever looks at the history of a page..<br />
<br />
== my project already has a wiki ..==<br />
Fine. In this case the haskellwiki wiki page will only have one link telling the user about your page.<br />
<br />
== progress and feedback ==<br />
I've send a short mail to about 100 maintainers to get to know what they think about this idea.<br />
<br />
Consider adding your name only for spam reasons (but send your emal address to marco-oweber@gmx.de so that I can associate them with packages on hackage to got to know who didn't reply)<br />
<br />
I support this idea:<br />
* marco-oweber@gmx.de (Marc Weber)<br />
* clawsie@fastmail.fm (Brad Clawsie)<br />
<br />
I support but want opt-out:<br />
* f.nfgnava@tznvy.pbz/rot13 (Sergey Astanin) I think default project wiki is a good thing for users, especially given that many projects don't have links neither to the web page nor to the bug tracker, some are unmaintained public domain, and some don't have even e-mail of the maintainer. However, I think that this wiki policy should be applied only to such “orphaned” projects without evident maintainer/infrastructure. When there is a valid link to project page, bug tracker or stand alone wiki, it's better to direct users there.<br />
<br />
I support but I want opt-in:<br />
* daniel@wagner-home.com (Daniel Wagner) I believe opt-in is the Right Thing, so would vote here even if I didn't have the misgivings I mention above<br />
* daniel.schoepe@googlemail.com (Daniel Schoepe) In general I think it's a very good idea, but imposing it on every package author might discourage some, especially people new to Hackage.<br />
* the idea makes me nervous, but I can live with opt-in (Eric Kow)<br />
<br />
I don't like the idea even if there was a warning such as "This content is contributed by maintainers and users and may be out of date.":<br />
<br />
If you vote here, make sure you've read "wiki alternatives". You can clean up the wiki page. You can't clean up foreign blogs.<br />
* EvanMartin (exactly what Duncan wrote -- I don't have time to vet a third-party page and keep it up to date; I have seen obsolete wikis for too many projects in my time. If I want to use a wiki I could just set it as the home page for my project. Consider adding a "wiki" link to the package description format.)<br />
<br />
I don't care:<br />
*<br />
<br />
I won't tell you:<br />
*<br />
<br />
== users view (beginners) ==<br />
Daniel Wagner told me that the thinks beginners will suffor most.<br />
So I'll start a thread on beginners@haskell.org and ask them :-)<br />
<br />
I'm a beginner, I don't mind reading outdated content. When I see a code snippet I'm going to copy paste it int ghci. If it doesn't work may be challenged and may fix it. Of course I'll contribute by solution and put it on the wiki. I think that such a scratch pad is a nice idea in general.<br />
* put your name here<br />
<br />
I'm a beginner and I fear reading about outdated content. This means that you fear the damage reading outdated content is bigger than the gains you have by reading up to date contents.<br />
* put your name here<br />
<br />
== mailinglist threads ==<br />
* [http://news.gmane.org/gmane.comp.lang.haskell.cafe haskell-cafe]<br />
<br />
* [http://thread.gmane.org/gmane.comp.lang.haskell.beginners/2942 beginners@haskell.org]<br />
<br />
<br />
== Notes ==<br />
You can watch this page</div>SergeyAstanin