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authorRobin H. Johnson <robbat2@gentoo.org>2015-08-08 13:49:04 -0700
committerRobin H. Johnson <robbat2@gentoo.org>2015-08-08 17:38:18 -0700
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tree3f91093cdb475e565ae857f1c5a7fd339e2d781e /dev-haskell/semigroupoids/metadata.xml
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proj/gentoo: Initial commit
This commit represents a new era for Gentoo: Storing the gentoo-x86 tree in Git, as converted from CVS. This commit is the start of the NEW history. Any historical data is intended to be grafted onto this point. Creation process: 1. Take final CVS checkout snapshot 2. Remove ALL ChangeLog* files 3. Transform all Manifests to thin 4. Remove empty Manifests 5. Convert all stale $Header$/$Id$ CVS keywords to non-expanded Git $Id$ 5.1. Do not touch files with -kb/-ko keyword flags. Signed-off-by: Robin H. Johnson <robbat2@gentoo.org> X-Thanks: Alec Warner <antarus@gentoo.org> - did the GSoC 2006 migration tests X-Thanks: Robin H. Johnson <robbat2@gentoo.org> - infra guy, herding this project X-Thanks: Nguyen Thai Ngoc Duy <pclouds@gentoo.org> - Former Gentoo developer, wrote Git features for the migration X-Thanks: Brian Harring <ferringb@gentoo.org> - wrote much python to improve cvs2svn X-Thanks: Rich Freeman <rich0@gentoo.org> - validation scripts X-Thanks: Patrick Lauer <patrick@gentoo.org> - Gentoo dev, running new 2014 work in migration X-Thanks: Michał Górny <mgorny@gentoo.org> - scripts, QA, nagging X-Thanks: All of other Gentoo developers - many ideas and lots of paint on the bikeshed
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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
+<pkgmetadata>
+ <herd>haskell</herd>
+ <longdescription>
+ Provides a wide array of semigroupoids and operations for working with semigroupds.
+
+ A Semigroupoid is a Category without the requirement of identity arrows for every object in the category.
+
+ When working with comonads you often have the @\&lt;*\&gt;@ portion of an @Applicative@, but
+ not the @pure@. This was captured in Uustalu and Vene's \"Essence of Dataflow Programming\"
+ in the form of the @ComonadZip@ class in the days before @Applicative@. Apply provides a weaker invariant, but for the comonads used for data flow programming (found in the streams package), this invariant is preserved. Applicative function composition forms a semigroupoid.
+
+ Similarly many structures are nearly a comonad, but not quite, for instance lists provide a reasonable 'extend' operation in the form of 'tails', but do not always contain a value.
+
+
+ Ideally the following relationships would hold:
+
+ &gt; Traversable &lt;---- Foldable &lt;--- Functor ------&gt; Alt ---------&gt; Plus Semigroupoid
+ &gt; | | | | |
+ &gt; v v v v v
+ &gt; Traversable1 &lt;--- Foldable1 Apply --------&gt; Applicative -&gt; Alternative Category
+ &gt; | | | |
+ &gt; v v v v
+ &gt; Bind ---------&gt; Monad -------&gt; MonadPlus Arrow
+ &gt;
+
+ Apply, Bind, and Extract give rise the Static, Kleisli and Cokleisli semigroupoids respectively.
+
+ This lets us remove many of the restrictions from various monad transformers
+ as in many cases the binding operation or @\&lt;*\&gt;@ operation does not require them.
+
+ Finally, to work with these weaker structures it is beneficial to have containers
+ that can provide stronger guarantees about their contents, so versions of 'Traversable'
+ and 'Foldable' that can be folded with just a 'Semigroup' are added.
+ </longdescription>
+ <use>
+ <flag name="comonad">You can disable the use of the `comonad` package using
+ `-f-comonad`. Disabling this is an unsupported configuration, but it may be
+ useful for accelerating builds in sandboxes for expert users. If disabled we
+ will not supply instances of `Comonad`</flag>
+ <flag name="containers">You can disable the use of the `containers` package
+ using `-f-containers`. Disabing this is an unsupported configuration, but it
+ may be useful for accelerating builds in sandboxes for expert users.</flag>
+ <flag name="contravariant">You can disable the use of the `contravariant`
+ package using `-f-contravariant`. Disabling this is an unsupported
+ configuration, but it may be useful for accelerating builds in sandboxes for
+ expert users. If disabled we will not supply instances of `Contravariant`</flag>
+ <flag name="distributive">You can disable the use of the `distributive`
+ package using `-f-distributive`. Disabling this is an unsupported
+ configuration, but it may be useful for accelerating builds in sandboxes for
+ expert users. If disabled we will not supply instances of `Distributive`</flag>
+ <flag name="tagged">You can disable the use of the `tagged` package
+ using `-f-tagged`. Disabing this is an unsupported
+ configuration, but it may be useful for accelerating builds in
+ sandboxes for expert users.</flag>
+ </use>
+ <upstream>
+ <remote-id type="github">ekmett/semigroupoids</remote-id>
+ </upstream>
+</pkgmetadata>