Hello community,
here is the log from the commit of package ghc-contravariant for
openSUSE:Factory checked in at 2018-05-30 12:05:26
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Comparing /work/SRC/openSUSE:Factory/ghc-contravariant (Old)
and /work/SRC/openSUSE:Factory/.ghc-contravariant.new (New)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Package is "ghc-contravariant"
Wed May 30 12:05:26 2018 rev:7 rq:607773 version:1.4.1
Changes:
--------
--- /work/SRC/openSUSE:Factory/ghc-contravariant/ghc-contravariant.changes
2017-09-15 21:28:34.449830719 +0200
+++ /work/SRC/openSUSE:Factory/.ghc-contravariant.new/ghc-contravariant.changes
2018-05-30 12:25:16.538388053 +0200
@@ -1,0 +2,9 @@
+Mon May 14 17:02:11 UTC 2018 - psim...@suse.com
+
+- Update contravariant to version 1.4.1 revision 1.
+ * Add `Semigroup` and `Monoid` instances for `Predicate`.
+ * Add lots of documentation explaining `Contravariant`, `Divisible`, and
+ `Decidable`.
+ * Fix some dodgy CPP usage that caused the build to fail on Eta.
+
+-------------------------------------------------------------------
Old:
----
contravariant-1.4.tar.gz
New:
----
contravariant-1.4.1.tar.gz
contravariant.cabal
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Other differences:
------------------
++++++ ghc-contravariant.spec ++++++
--- /var/tmp/diff_new_pack.5lRVyB/_old 2018-05-30 12:25:17.218365832 +0200
+++ /var/tmp/diff_new_pack.5lRVyB/_new 2018-05-30 12:25:17.222365701 +0200
@@ -1,7 +1,7 @@
#
# spec file for package ghc-contravariant
#
-# Copyright (c) 2017 SUSE LINUX GmbH, Nuernberg, Germany.
+# Copyright (c) 2018 SUSE LINUX GmbH, Nuernberg, Germany.
#
# All modifications and additions to the file contributed by third parties
# remain the property of their copyright owners, unless otherwise agreed
@@ -18,20 +18,19 @@
%global pkg_name contravariant
Name: ghc-%{pkg_name}
-Version: 1.4
+Version: 1.4.1
Release: 0
Summary: Contravariant functors
License: BSD-3-Clause
Group: Development/Libraries/Haskell
URL: https://hackage.haskell.org/package/%{pkg_name}
Source0:
https://hackage.haskell.org/package/%{pkg_name}-%{version}/%{pkg_name}-%{version}.tar.gz
+Source1:
https://hackage.haskell.org/package/%{pkg_name}-%{version}/revision/1.cabal#/%{pkg_name}.cabal
BuildRequires: ghc-Cabal-devel
BuildRequires: ghc-StateVar-devel
BuildRequires: ghc-rpm-macros
-BuildRequires: ghc-semigroups-devel
BuildRequires: ghc-transformers-compat-devel
BuildRequires: ghc-transformers-devel
-BuildRequires: ghc-void-devel
%description
Contravariant functors.
@@ -49,6 +48,7 @@
%prep
%setup -q -n %{pkg_name}-%{version}
+cp -p %{SOURCE1} %{pkg_name}.cabal
%build
%ghc_lib_build
@@ -63,9 +63,9 @@
%ghc_pkg_recache
%files -f %{name}.files
-%doc LICENSE
+%license LICENSE
%files devel -f %{name}-devel.files
-%doc CHANGELOG.markdown
+%doc CHANGELOG.markdown README.markdown
%changelog
++++++ contravariant-1.4.tar.gz -> contravariant-1.4.1.tar.gz ++++++
diff -urN '--exclude=CVS' '--exclude=.cvsignore' '--exclude=.svn'
'--exclude=.svnignore' old/contravariant-1.4/.travis.yml
new/contravariant-1.4.1/.travis.yml
--- old/contravariant-1.4/.travis.yml 2016-01-16 22:55:58.000000000 +0100
+++ new/contravariant-1.4.1/.travis.yml 2018-01-18 20:29:34.000000000 +0100
@@ -1,62 +1,155 @@
-# NB: don't set `language: haskell` here
+# This Travis job script has been generated by a script via
+#
+# runghc make_travis_yml_2.hs '-o' '.travis.yml'
'--irc-channel=irc.freenode.org#haskell-lens' '--no-no-tests-no-bench'
'--no-installed' 'cabal.project'
+#
+# For more information, see https://github.com/hvr/multi-ghc-travis
+#
+language: c
+sudo: false
-# See also https://github.com/hvr/multi-ghc-travis for more information
-env:
- # we have to use CABALVER=1.16 for GHC<7.6 as well, as there's
- # no package for earlier cabal versions in the PPA
- - GHCVER=7.4.2 CABALVER=1.16
- - GHCVER=7.6.3 CABALVER=1.16
- - GHCVER=7.8.4 CABALVER=1.18
- - GHCVER=7.10.1 CABALVER=1.22
- - GHCVER=head CABALVER=1.22
+git:
+ submodules: false # whether to recursively clone submodules
+
+notifications:
+ irc:
+ channels:
+ - "irc.freenode.org#haskell-lens"
+ skip_join: true
+ template:
+ - "\x0313contravariant\x03/\x0306%{branch}\x03 \x0314%{commit}\x03
%{build_url} %{message}"
+
+cache:
+ directories:
+ - $HOME/.cabal/packages
+ - $HOME/.cabal/store
+
+before_cache:
+ - rm -fv $HOME/.cabal/packages/hackage.haskell.org/build-reports.log
+ # remove files that are regenerated by 'cabal update'
+ - rm -fv $HOME/.cabal/packages/hackage.haskell.org/00-index.*
+ - rm -fv $HOME/.cabal/packages/hackage.haskell.org/*.json
+ - rm -fv $HOME/.cabal/packages/hackage.haskell.org/01-index.cache
+ - rm -fv $HOME/.cabal/packages/hackage.haskell.org/01-index.tar
+ - rm -fv $HOME/.cabal/packages/hackage.haskell.org/01-index.tar.idx
+
+ - rm -rfv $HOME/.cabal/packages/head.hackage
+
+addons:
+ apt:
+ packages: &apt_packages
+ - ghc-ppa-tools
+ - hlint
matrix:
+ include:
+ - compiler: "ghc-7.0.4"
+ # env: TEST=--disable-tests BENCH=--disable-benchmarks
+ addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4],
sources: [hvr-ghc]}}
+ - compiler: "ghc-7.2.2"
+ # env: TEST=--disable-tests BENCH=--disable-benchmarks
+ addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.2.2],
sources: [hvr-ghc]}}
+ - compiler: "ghc-7.4.2"
+ # env: TEST=--disable-tests BENCH=--disable-benchmarks
+ addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.4.2],
sources: [hvr-ghc]}}
+ - compiler: "ghc-7.6.3"
+ # env: TEST=--disable-tests BENCH=--disable-benchmarks
+ addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.6.3],
sources: [hvr-ghc]}}
+ - compiler: "ghc-7.8.4"
+ # env: TEST=--disable-tests BENCH=--disable-benchmarks
+ addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.8.4],
sources: [hvr-ghc]}}
+ - compiler: "ghc-7.10.3"
+ # env: TEST=--disable-tests BENCH=--disable-benchmarks
+ addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.10.3],
sources: [hvr-ghc]}}
+ - compiler: "ghc-8.0.2"
+ # env: TEST=--disable-tests BENCH=--disable-benchmarks
+ addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-8.0.2],
sources: [hvr-ghc]}}
+ - compiler: "ghc-8.2.2"
+ # env: TEST=--disable-tests BENCH=--disable-benchmarks
+ addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-8.2.2],
sources: [hvr-ghc]}}
+ - compiler: "ghc-8.4.1"
+ env: GHCHEAD=true
+ addons: {apt: {packages: [*apt_packages,cabal-install-head,ghc-8.4.1],
sources: [hvr-ghc]}}
+ - compiler: "ghc-head"
+ env: GHCHEAD=true
+ addons: {apt: {packages: [*apt_packages,cabal-install-head,ghc-head],
sources: [hvr-ghc]}}
+
allow_failures:
- - env: GHCVER=head CABALVER=1.22
+ - compiler: "ghc-7.0.4"
+ - compiler: "ghc-7.2.2"
+ - compiler: "ghc-8.4.1"
+ - compiler: "ghc-head"
-# Note: the distinction between `before_install` and `install` is not
-# important.
before_install:
- - travis_retry sudo add-apt-repository -y ppa:hvr/ghc
- - travis_retry sudo apt-get update
- - travis_retry sudo apt-get install cabal-install-$CABALVER ghc-$GHCVER
- - export PATH=/opt/ghc/$GHCVER/bin:/opt/cabal/$CABALVER/bin:$PATH
- - cabal --version
+ - HC=${CC}
+ - HCPKG=${HC/ghc/ghc-pkg}
+ - unset CC
+ - ROOTDIR=$(pwd)
+ - mkdir -p $HOME/.local/bin
+ - "PATH=/opt/ghc/bin:/opt/ghc-ppa-tools/bin:$HOME/local/bin:$PATH"
+ - HCNUMVER=$(( $(${HC} --numeric-version|sed -E
's/([0-9]+)\.([0-9]+)\.([0-9]+).*/\1 * 10000 + \2 * 100 + \3/') ))
+ - echo $HCNUMVER
install:
- - travis_retry cabal update
- - cabal install --only-dependencies
- - travis_retry sudo apt-get -q -y install hlint || cabal install hlint
-
-# Here starts the actual work to be performed for the package under
-# test; any command which exits with a non-zero exit code causes the
-# build to fail.
+ - cabal --version
+ - echo "$(${HC} --version) [$(${HC} --print-project-git-commit-id 2>
/dev/null || echo '?')]"
+ - BENCH=${BENCH---enable-benchmarks}
+ - TEST=${TEST---enable-tests}
+ - HADDOCK=${HADDOCK-true}
+ - INSTALLED=${INSTALLED-true}
+ - GHCHEAD=${GHCHEAD-false}
+ - travis_retry cabal update -v
+ - "sed -i.bak 's/^jobs:/-- jobs:/' ${HOME}/.cabal/config"
+ - rm -fv cabal.project cabal.project.local
+ # Overlay Hackage Package Index for GHC HEAD:
https://github.com/hvr/head.hackage
+ - |
+ if $GHCHEAD; then
+ sed -i.bak 's/-- allow-newer:.*/allow-newer: *:base, *:template-haskell,
*:ghc, *:Cabal/' ${HOME}/.cabal/config
+
+ echo 'repository head.hackage'
>> ${HOME}/.cabal/config
+ echo ' url: http://head.hackage.haskell.org/'
>> ${HOME}/.cabal/config
+ echo ' secure: True'
>> ${HOME}/.cabal/config
+ echo ' root-keys:
07c59cb65787dedfaef5bd5f987ceb5f7e5ebf88b904bbd4c5cbdeb2ff71b740' >>
${HOME}/.cabal/config
+ echo '
2e8555dde16ebd8df076f1a8ef13b8f14c66bad8eafefd7d9e37d0ed711821fb' >>
${HOME}/.cabal/config
+ echo '
8f79fd2389ab2967354407ec852cbe73f2e8635793ac446d09461ffb99527f6e' >>
${HOME}/.cabal/config
+ echo ' key-threshold: 3'
>> ${HOME}/.cabal.config
+
+ cabal new-update head.hackage -v
+ fi
+ - grep -Ev -- '^\s*--' ${HOME}/.cabal/config | grep -Ev '^\s*$'
+ - "printf 'packages: \".\"\\n' > cabal.project"
+ - cat cabal.project
+ - if [ -f "./configure.ac" ]; then
+ (cd "." && autoreconf -i);
+ fi
+ - rm -f cabal.project.freeze
+ - cabal new-build -w ${HC} ${TEST} ${BENCH} --project-file="cabal.project"
--dep -j2 all
+ - rm -rf "."/.ghc.environment.* "."/dist
+ - DISTDIR=$(mktemp -d /tmp/dist-test.XXXX)
+
+# Here starts the actual work to be performed for the package under test;
+# any command which exits with a non-zero exit code causes the build to fail.
script:
- # -v2 provides useful information for debugging
- - cabal configure -v2
+ # test that source-distributions can be generated
+ - (cd "." && cabal sdist)
+ - mv "."/dist/contravariant-*.tar.gz ${DISTDIR}/
+ - cd ${DISTDIR} || false
+ - find . -maxdepth 1 -name '*.tar.gz' -exec tar -xvf '{}' \;
+ - "printf 'packages: contravariant-*/*.cabal\\n' > cabal.project"
+ - cat cabal.project
+
+
+ # build & run tests, build benchmarks
+ - cabal new-build -w ${HC} ${TEST} ${BENCH} all
+
+ # cabal check
+ - (cd contravariant-* && cabal check)
+
+ # haddock
+ - rm -rf ./dist-newstyle
+ - if $HADDOCK; then cabal new-haddock -w ${HC} ${TEST} ${BENCH} all; else
echo "Skipping haddock generation";fi
- # this builds all libraries and executables
- # (including tests/benchmarks)
- - cabal build
-
- # tests that a source-distribution can be generated
- - cabal sdist
- - hlint src --cpp-define HLINT
-
- # check that the generated source-distribution can be built & installed
- - export SRC_TGZ=$(cabal info . | awk '{print $2 ".tar.gz";exit}') ;
- cd dist/;
- if [ -f "$SRC_TGZ" ]; then
- cabal install --force-reinstalls "$SRC_TGZ";
- else
- echo "expected '$SRC_TGZ' not found";
- exit 1;
- fi
+ # hlint
+ - (cd contravariant-* && hlint src --cpp-define=HLINT)
-notifications:
- irc:
- channels:
- - "irc.freenode.org#haskell-lens"
- skip_join: true
- template:
- - "\x0313contravariant\x03/\x0306%{branch}\x03 \x0314%{commit}\x03
%{build_url} %{message}"
+# REGENDATA
["-o",".travis.yml","--irc-channel=irc.freenode.org#haskell-lens","--no-no-tests-no-bench","--no-installed","cabal.project"]
+# EOF
diff -urN '--exclude=CVS' '--exclude=.cvsignore' '--exclude=.svn'
'--exclude=.svnignore' old/contravariant-1.4/CHANGELOG.markdown
new/contravariant-1.4.1/CHANGELOG.markdown
--- old/contravariant-1.4/CHANGELOG.markdown 2016-01-16 22:55:58.000000000
+0100
+++ new/contravariant-1.4.1/CHANGELOG.markdown 2018-01-18 20:29:34.000000000
+0100
@@ -1,3 +1,10 @@
+1.4.1 [2018.01.18]
+------------------
+* Add `Semigroup` and `Monoid` instances for `Predicate`.
+* Add lots of documentation explaining `Contravariant`, `Divisible`, and
+ `Decidable`.
+* Fix some dodgy CPP usage that caused the build to fail on Eta.
+
1.4
---
* Improved the performance of `Deciding` at the cost of downgrading it to
`Trustworthy`.
@@ -43,6 +50,10 @@
-----
* Fix build on GHC 7.0.4
+1.2
+-----
+* Renamed `Data.Functor.Contravariant.Applicative` to
`Data.Functor.Contravariant.Divisible`
+
1.1.1
-----
* Added `Data.Functor.Contravariant.Applicative`
diff -urN '--exclude=CVS' '--exclude=.cvsignore' '--exclude=.svn'
'--exclude=.svnignore' old/contravariant-1.4/HLint.hs
new/contravariant-1.4.1/HLint.hs
--- old/contravariant-1.4/HLint.hs 2016-01-16 22:55:58.000000000 +0100
+++ new/contravariant-1.4.1/HLint.hs 2018-01-18 20:29:34.000000000 +0100
@@ -1,2 +1,3 @@
ignore "Eta reduce"
-
+ignore "Use const"
+ignore "Use first"
diff -urN '--exclude=CVS' '--exclude=.cvsignore' '--exclude=.svn'
'--exclude=.svnignore' old/contravariant-1.4/README.markdown
new/contravariant-1.4.1/README.markdown
--- old/contravariant-1.4/README.markdown 1970-01-01 01:00:00.000000000
+0100
+++ new/contravariant-1.4.1/README.markdown 2018-01-18 20:29:34.000000000
+0100
@@ -0,0 +1,17 @@
+contravariant
+=============
+
+[](https://hackage.haskell.org/package/contravariant)
+[](http://travis-ci.org/ekmett/contravariant)
+
+Haskell 98 contravariant functors
+
+Contact Information
+-------------------
+
+Contributions and bug reports are welcome!
+
+Please feel free to contact me through github or on the #haskell IRC channel
on irc.freenode.net.
+
+-Edward Kmett
+
diff -urN '--exclude=CVS' '--exclude=.cvsignore' '--exclude=.svn'
'--exclude=.svnignore' old/contravariant-1.4/contravariant.cabal
new/contravariant-1.4.1/contravariant.cabal
--- old/contravariant-1.4/contravariant.cabal 2016-01-16 22:55:58.000000000
+0100
+++ new/contravariant-1.4.1/contravariant.cabal 2018-01-18 20:29:34.000000000
+0100
@@ -1,6 +1,6 @@
name: contravariant
category: Control, Data
-version: 1.4
+version: 1.4.1
license: BSD3
cabal-version: >= 1.6
license-file: LICENSE
@@ -11,11 +11,21 @@
bug-reports: http://github.com/ekmett/contravariant/issues
copyright: Copyright (C) 2007-2015 Edward A. Kmett
synopsis: Contravariant functors
-description: Contravariant functors
+description: Contravariant functors.
build-type: Simple
+tested-with: GHC == 7.0.4
+ , GHC == 7.2.2
+ , GHC == 7.4.2
+ , GHC == 7.6.3
+ , GHC == 7.8.4
+ , GHC == 7.10.3
+ , GHC == 8.0.2
+ , GHC == 8.2.2
+ , GHC == 8.4.1
extra-source-files:
.travis.yml
CHANGELOG.markdown
+ README.markdown
HLint.hs
source-repository head
@@ -56,13 +66,15 @@
build-depends:
base < 5,
transformers >= 0.2 && < 0.6,
- transformers-compat >= 0.3 && < 1,
- void >= 0.6 && < 1
+ transformers-compat >= 0.3 && < 1
+
+ if !impl(ghc >= 7.9)
+ build-depends: void >= 0.6 && < 1
if flag(tagged) && !impl(ghc >= 7.7)
build-depends: tagged >= 0.4.4 && < 1
- if flag(semigroups)
+ if flag(semigroups) && !impl(ghc >= 7.11)
build-depends: semigroups >= 0.15.2 && < 1
if flag(StateVar)
diff -urN '--exclude=CVS' '--exclude=.cvsignore' '--exclude=.svn'
'--exclude=.svnignore'
old/contravariant-1.4/src/Data/Functor/Contravariant/Divisible.hs
new/contravariant-1.4.1/src/Data/Functor/Contravariant/Divisible.hs
--- old/contravariant-1.4/src/Data/Functor/Contravariant/Divisible.hs
2016-01-16 22:55:58.000000000 +0100
+++ new/contravariant-1.4.1/src/Data/Functor/Contravariant/Divisible.hs
2018-01-18 20:29:34.000000000 +0100
@@ -20,6 +20,15 @@
Divisible(..), divided, conquered, liftD
-- * Contravariant Alternative
, Decidable(..), chosen, lost
+ -- * Mathematical definitions
+ -- ** Divisible
+ -- $divisible
+
+ -- *** A note on 'conquer'
+ -- $conquer
+
+ -- ** Decidable
+ -- $decidable
) where
import Control.Applicative
@@ -56,7 +65,7 @@
import Data.Proxy
#endif
-#if MIN_VERSION_StateVar
+#ifdef MIN_VERSION_StateVar
import Data.StateVar
#endif
@@ -73,48 +82,73 @@
--
-- A 'Divisible' contravariant functor is the contravariant analogue of
'Applicative'.
--
--- In denser jargon, a 'Divisible' contravariant functor is a monoid object in
the category
--- of presheaves from Hask to Hask, equipped with Day convolution mapping the
Cartesian
--- product of the source to the Cartesian product of the target.
+-- Continuing the intuition that 'Contravariant' functors consume input, a
'Divisible'
+-- contravariant functor also has the ability to be composed "beside" another
contravariant
+-- functor.
--
--- By way of contrast, an 'Applicative' functor can be viewed as a monoid
object in the
--- category of copresheaves from Hask to Hask, equipped with Day convolution
mapping the
--- Cartesian product of the source to the Cartesian product of the target.
+-- Serializers provide a good example of 'Divisible' contravariant functors.
To begin
+-- let's start with the type of serializers for specific types:
--
--- Given the canonical diagonal morphism:
+-- @
+-- newtype Serializer a = Serializer { runSerializer :: a -> ByteString }
+-- @
+--
+-- This is a contravariant functor:
--
-- @
--- delta a = (a,a)
+-- instance Contravariant Serializer where
+-- contramap f s = Serializer (runSerializer s . f)
-- @
--
--- @'divide' 'delta'@ should be associative with 'conquer' as a unit
+-- That is, given a serializer for @a@ (@s :: Serializer a@), and a way to turn
+-- @b@s into @a@s (a mapping @f :: b -> a@), we have a serializer for @b@:
+-- @contramap f s :: Serializer b@.
+--
+-- Divisible gives us a way to combine two serializers that focus on different
+-- parts of a structure. If we postulate the existance of two primitive
+-- serializers - @string :: Serializer String@ and @int :: Serializer Int@, we
+-- would like to be able to combine these into a serializer for pairs of
+-- @String@s and @Int@s. How can we do this? Simply run both serializer and
+-- combine their output!
--
-- @
--- 'divide' 'delta' m 'conquer' = m
--- 'divide' 'delta' 'conquer' m = m
--- 'divide' 'delta' ('divide' 'delta' m n) o = 'divide' 'delta' m ('divide'
'delta' n o)
+-- data StringAndInt = StringAndInt String Int
+--
+-- stringAndInt :: Serializer StringAndInt
+-- stringAndInt = Serializer $ \(StringAndInt s i) ->
+-- let sBytes = runSerializer string s
+-- iBytes = runSerializer int i
+-- in sBytes <> iBytes
-- @
--
--- With more general arguments you'll need to reassociate and project using
the monoidal
--- structure of the source category. (Here fst and snd are used in lieu of the
more restricted
--- lambda and rho, but this construction works with just a monoidal category.)
+-- 'divide' is a generalization by also taking a 'contramap' like function to
+-- split any @a@ into a pair. This conveniently allows you to target fields of
+-- a record, for instance, by extracting the values under two fields and
+-- combining them into a tuple.
+--
+-- To complete the example, here is how to write @stringAndInt@ using a
+-- @Divisible@ instance:
--
-- @
--- 'divide' f m 'conquer' = 'contramap' ('fst' . f) m
--- 'divide' f 'conquer' m = 'contramap' ('snd' . f) m
--- 'divide' f ('divide' g m n) o = 'divide' f' m ('divide' 'id' n o) where
--- f' a = case f a of (bc,d) -> case g bc of (b,c) -> (a,(b,c))
+-- instance Divisible Serializer where
+-- conquer = Serializer (const mempty)
+--
+-- divide toBC bSerializer cSerializer = Serializer $ \a ->
+-- case toBC a of
+-- (b, c) ->
+-- let bBytes = runSerializer bSerializer b
+-- cBytes = runSerializer cSerializer c
+-- in bBytes <> cBytes
+--
+-- stringAndInt :: Serializer StringAndInt
+-- stringAndInt =
+-- divide (\(StringAndInt s i) -> (s, i)) string int
-- @
+--
class Contravariant f => Divisible f where
divide :: (a -> (b, c)) -> f b -> f c -> f a
- -- | The underlying theory would suggest that this should be:
- --
- -- @
- -- conquer :: (a -> ()) -> f a
- -- @
- --
- -- However, as we are working over a Cartesian category (Hask) and the
Cartesian product, such an input
- -- morphism is uniquely determined to be @'const' 'mempty'@, so we elide it.
+
+ -- | Conquer acts as an identity for combining @Divisible@ functors.
conquer :: f a
-- |
@@ -280,7 +314,7 @@
conquer = Proxy
#endif
-#if MIN_VERSION_StateVar
+#ifdef MIN_VERSION_StateVar
instance Divisible SettableStateVar where
divide k (SettableStateVar l) (SettableStateVar r) = SettableStateVar $ \ a
-> case k a of
(b, c) -> l b >> r c
@@ -302,26 +336,58 @@
-- * Contravariant Alternative
--------------------------------------------------------------------------------
--- |
+-- | A 'Decidable' contravariant functor is the contravariant analogue of
'Alternative'.
--
--- A 'Divisible' contravariant functor is a monoid object in the category of
presheaves
--- from Hask to Hask, equipped with Day convolution mapping the cartesian
product of the
--- source to the Cartesian product of the target.
+-- Noting the superclass constraint that @f@ must also be 'Divisible', a
@Decidable@
+-- functor has the ability to "fan out" input, under the intuition that
contravariant
+-- functors consume input.
+--
+-- In the dicussion for @Divisible@, an example was demonstrated with
@Serializer@s,
+-- that turn @a@s into @ByteString@s. @Divisible@ allowed us to serialize the
/product/
+-- of multiple values by concatenation. By making our @Serializer@ also
@Decidable@-
+-- we now have the ability to serialize the /sum/ of multiple values - for
example
+-- different constructors in an ADT.
+--
+-- Consider serializing arbitrary identifiers that can be either @String@s or
@Int@s:
--
-- @
--- 'choose' 'Left' m ('lose' f) = m
--- 'choose' 'Right' ('lose' f) m = m
--- 'choose' f ('choose' g m n) o = 'divide' f' m ('divide' 'id' n o) where
--- f' bcd = 'either' ('either' 'id' ('Right' . 'Left') . g) ('Right' .
'Right') . f
+-- data Identifier = StringId String | IntId Int
-- @
--
--- In addition, we expect the same kind of distributive law as is satisfied by
the usual
--- covariant 'Alternative', w.r.t 'Applicative', which should be fully
formulated and
--- added here at some point!
-
+-- We know we have serializers for @String@s and @Int@s, but how do we combine
them
+-- into a @Serializer@ for @Identifier@? Essentially, our @Serializer@ needs to
+-- scrutinise the incoming value and choose how to serialize it:
+--
+-- @
+-- identifier :: Serializer Identifier
+-- identifier = Serializer $ \identifier ->
+-- case identifier of
+-- StringId s -> runSerializer string s
+-- IntId i -> runSerializer int i
+-- @
+--
+-- It is exactly this notion of choice that @Decidable@ encodes. Hence if we
add
+-- an instance of @Decidable@ for @Serializer@...
+--
+-- @
+-- instance Decidable Serializer where
+-- lose f = Serializer $ \a -> absurd (f a)
+-- choose split l r = Serializer $ \a ->
+-- either (runSerializer l) (runSerializer r) (split a)
+-- @
+--
+-- Then our @identifier@ @Serializer@ is
+--
+-- @
+-- identifier :: Serializer Identifier
+-- identifier = choose toEither string int where
+-- toEither (StringId s) = Left s
+-- toEither (IntId i) = Right i
+-- @
class Divisible f => Decidable f where
- -- | The only way to win is not to play.
+ -- | Acts as identity to 'choose'.
lose :: (a -> Void) -> f a
+
choose :: (a -> Either b c) -> f b -> f c -> f a
-- |
@@ -483,10 +549,72 @@
choose _ Proxy Proxy = Proxy
#endif
-#if MIN_VERSION_StateVar
-instance Decidable SettableVar where
+#ifdef MIN_VERSION_StateVar
+instance Decidable SettableStateVar where
lose k = SettableStateVar (absurd . k)
choose k (SettableStateVar l) (SettableStateVar r) = SettableStateVar $ \ a
-> case k a of
Left b -> l b
Right c -> r c
#endif
+
+-- $divisible
+--
+-- In denser jargon, a 'Divisible' contravariant functor is a monoid object in
the category
+-- of presheaves from Hask to Hask, equipped with Day convolution mapping the
Cartesian
+-- product of the source to the Cartesian product of the target.
+--
+-- By way of contrast, an 'Applicative' functor can be viewed as a monoid
object in the
+-- category of copresheaves from Hask to Hask, equipped with Day convolution
mapping the
+-- Cartesian product of the source to the Cartesian product of the target.
+--
+-- Given the canonical diagonal morphism:
+--
+-- @
+-- delta a = (a,a)
+-- @
+--
+-- @'divide' 'delta'@ should be associative with 'conquer' as a unit
+--
+-- @
+-- 'divide' 'delta' m 'conquer' = m
+-- 'divide' 'delta' 'conquer' m = m
+-- 'divide' 'delta' ('divide' 'delta' m n) o = 'divide' 'delta' m ('divide'
'delta' n o)
+-- @
+--
+-- With more general arguments you'll need to reassociate and project using
the monoidal
+-- structure of the source category. (Here fst and snd are used in lieu of the
more restricted
+-- lambda and rho, but this construction works with just a monoidal category.)
+--
+-- @
+-- 'divide' f m 'conquer' = 'contramap' ('fst' . f) m
+-- 'divide' f 'conquer' m = 'contramap' ('snd' . f) m
+-- 'divide' f ('divide' g m n) o = 'divide' f' m ('divide' 'id' n o) where
+-- f' a = case f a of (bc,d) -> case g bc of (b,c) -> (a,(b,c))
+-- @
+
+-- $conquer
+-- The underlying theory would suggest that this should be:
+--
+-- @
+-- conquer :: (a -> ()) -> f a
+-- @
+--
+-- However, as we are working over a Cartesian category (Hask) and the
Cartesian product, such an input
+-- morphism is uniquely determined to be @'const' 'mempty'@, so we elide it.
+
+-- $decidable
+--
+-- A 'Divisible' contravariant functor is a monoid object in the category of
presheaves
+-- from Hask to Hask, equipped with Day convolution mapping the cartesian
product of the
+-- source to the Cartesian product of the target.
+--
+-- @
+-- 'choose' 'Left' m ('lose' f) = m
+-- 'choose' 'Right' ('lose' f) m = m
+-- 'choose' f ('choose' g m n) o = 'divide' f' m ('divide' 'id' n o) where
+-- f' bcd = 'either' ('either' 'id' ('Right' . 'Left') . g) ('Right' .
'Right') . f
+-- @
+--
+-- In addition, we expect the same kind of distributive law as is satisfied by
the usual
+-- covariant 'Alternative', w.r.t 'Applicative', which should be fully
formulated and
+-- added here at some point!
diff -urN '--exclude=CVS' '--exclude=.cvsignore' '--exclude=.svn'
'--exclude=.svnignore' old/contravariant-1.4/src/Data/Functor/Contravariant.hs
new/contravariant-1.4.1/src/Data/Functor/Contravariant.hs
--- old/contravariant-1.4/src/Data/Functor/Contravariant.hs 2016-01-16
22:55:58.000000000 +0100
+++ new/contravariant-1.4.1/src/Data/Functor/Contravariant.hs 2018-01-18
20:29:34.000000000 +0100
@@ -95,7 +95,7 @@
import Data.Monoid (Monoid(..))
#endif
-#ifdef MIN_VERSION_semigroups
+#if defined(MIN_VERSION_semigroups) || __GLASGOW_HASKELL__ >= 711
import Data.Semigroup (Semigroup(..))
#endif
@@ -118,7 +118,32 @@
import Prelude hiding ((.),id)
--- | Any instance should be subject to the following laws:
+-- | The class of contravariant functors.
+--
+-- Whereas in Haskell, one can think of a 'Functor' as containing or producing
+-- values, a contravariant functor is a functor that can be thought of as
+-- /consuming/ values.
+--
+-- As an example, consider the type of predicate functions @a -> Bool@. One
+-- such predicate might be @negative x = x < 0@, which
+-- classifies integers as to whether they are negative. However, given this
+-- predicate, we can re-use it in other situations, providing we have a way to
+-- map values /to/ integers. For instance, we can use the @negative@ predicate
+-- on a person's bank balance to work out if they are currently overdrawn:
+--
+-- @
+-- newtype Predicate a = Predicate { getPredicate :: a -> Bool }
+--
+-- instance Contravariant Predicate where
+-- contramap f (Predicate p) = Predicate (p . f)
+-- | `- First, map the input...
+-- `----- then apply the predicate.
+--
+-- overdrawn :: Predicate Person
+-- overdrawn = contramap personBankBalance negative
+-- @
+--
+-- Any instance should be subject to the following laws:
--
-- > contramap id = id
-- > contramap f . contramap g = contramap (g . f)
@@ -137,7 +162,7 @@
(>$) = contramap . const
-- | If 'f' is both 'Functor' and 'Contravariant' then by the time you factor
in the laws
--- of each of those classes, it can't actually use it's argument in any
meaningful capacity.
+-- of each of those classes, it can't actually use its argument in any
meaningful capacity.
--
-- This method is surprisingly useful. Where both instances exist and are
lawful we have
-- the following laws:
@@ -285,6 +310,19 @@
instance Contravariant Predicate where
contramap f g = Predicate $ getPredicate g . f
+#if defined(MIN_VERSION_semigroups) || __GLASGOW_HASKELL__ >= 711
+instance Semigroup (Predicate a) where
+ Predicate p <> Predicate q = Predicate $ \a -> p a && q a
+#endif
+
+instance Monoid (Predicate a) where
+ mempty = Predicate $ const True
+#if defined(MIN_VERSION_semigroups) || __GLASGOW_HASKELL__ >= 711
+ mappend = (<>)
+#else
+ mappend (Predicate p) (Predicate q) = Predicate $ \a -> p a && q a
+#endif
+
-- | Defines a total ordering on a type as per 'compare'
--
-- This condition is not checked by the types. You must ensure that the
supplied
@@ -299,7 +337,7 @@
instance Contravariant Comparison where
contramap f g = Comparison $ on (getComparison g) f
-#ifdef MIN_VERSION_semigroups
+#if defined(MIN_VERSION_semigroups) || __GLASGOW_HASKELL__ >= 711
instance Semigroup (Comparison a) where
Comparison p <> Comparison q = Comparison $ mappend p q
#endif
@@ -344,7 +382,7 @@
instance Contravariant Equivalence where
contramap f g = Equivalence $ on (getEquivalence g) f
-#ifdef MIN_VERSION_semigroups
+#if defined(MIN_VERSION_semigroups) || __GLASGOW_HASKELL__ >= 711
instance Semigroup (Equivalence a) where
Equivalence p <> Equivalence q = Equivalence $ \a b -> p a b && q a b
#endif
@@ -375,7 +413,7 @@
instance Contravariant (Op a) where
contramap f g = Op (getOp g . f)
-#ifdef MIN_VERSION_semigroups
+#if defined(MIN_VERSION_semigroups) || __GLASGOW_HASKELL__ >= 711
instance Semigroup a => Semigroup (Op a b) where
Op p <> Op q = Op $ \a -> p a <> q a
#endif
++++++ contravariant.cabal ++++++
name: contravariant
category: Control, Data
version: 1.4.1
x-revision: 1
license: BSD3
cabal-version: >= 1.6
license-file: LICENSE
author: Edward A. Kmett
maintainer: Edward A. Kmett <ekm...@gmail.com>
stability: provisional
homepage: http://github.com/ekmett/contravariant/
bug-reports: http://github.com/ekmett/contravariant/issues
copyright: Copyright (C) 2007-2015 Edward A. Kmett
synopsis: Contravariant functors
description: Contravariant functors.
build-type: Simple
tested-with: GHC == 7.0.4
, GHC == 7.2.2
, GHC == 7.4.2
, GHC == 7.6.3
, GHC == 7.8.4
, GHC == 7.10.3
, GHC == 8.0.2
, GHC == 8.2.2
, GHC == 8.4.1
extra-source-files:
.travis.yml
CHANGELOG.markdown
README.markdown
HLint.hs
source-repository head
type: git
location: git://github.com/ekmett/contravariant.git
flag tagged
description:
You can disable the use of the `tagged` package using `-f-tagged`.
.
Disabling this is an unsupported configuration, but it may be useful for
accelerating builds in sandboxes for expert users.
default: True
manual: True
flag semigroups
description:
You can disable the use of the `semigroups` package using `-f-semigroups`.
.
Disabling this is an unsupported configuration, but it may be useful for
accelerating builds in sandboxes for expert users.
default: True
manual: True
flag safe
description: Get Safe guarantees rather than merely Trustworthy, but with
worse constant factors.
default: False
manual: True
flag StateVar
description:
You can disable the use of the `StateVar` package using `-f-StateVar`.
.
Disabling this is an unsupported configuration, but it may be useful for
accelerating builds in sandboxes for expert users.
default: True
manual: True
library
hs-source-dirs: src
build-depends:
base < 4.12,
transformers >= 0.2 && < 0.6,
transformers-compat >= 0.3 && < 1
if !impl(ghc >= 7.9)
build-depends: void >= 0.6 && < 1
if flag(tagged) && !impl(ghc >= 7.7)
build-depends: tagged >= 0.4.4 && < 1
if flag(semigroups) && !impl(ghc >= 7.11)
build-depends: semigroups >= 0.15.2 && < 1
if flag(StateVar)
build-depends: StateVar >= 1.1 && < 1.2
if impl(ghc >= 7.2 && < 7.6)
build-depends: ghc-prim
if flag(safe)
cpp-options: -DSAFE
exposed-modules:
Data.Functor.Contravariant
Data.Functor.Contravariant.Compose
Data.Functor.Contravariant.Divisible
if impl(ghc >= 7.4)
exposed-modules: Data.Functor.Contravariant.Generic
ghc-options: -Wall
