doc/hcar/Cabal-201611.tex

   1 % Cabal-MC.tex
   2 \begin{hcarentry}{Cabal}
   3 \label{cabal}%\label{hackage}\label{hackagedb}%
   4 \report{Mikhail Glushenkov}%11/16
   5 \status{Stable, actively developed}
   6 \makeheader
   7
   8 \subsubsection*{Background}
   9
  10 Cabal is the standard packaging system for Haskell software. It specifies a
  11 standard way in which Haskell libraries and applications can be packaged so
  12 that it is easy for consumers to use them, or re-package them, regardless of
  13 the Haskell implementation or installation platform.
  14
  15 \texttt{cabal-install} is the command line interface for the Cabal and Hackage
  16 system. It provides a command line program \texttt{cabal} which has
  17 sub-commands for installing and managing Haskell packages.
  18
  19 \subsubsection*{Recent Progress}
  20
  21 We've recently produced
  22 \href{https://mail.haskell.org/pipermail/cabal-devel/2016-December/010384.html}{new
  23   point releases} of Cabal/\texttt{cabal-install} from the 1.24
  24 branch. Among other things, Cabal 1.24.2.0 includes a
  25 \href{https://gitlab.haskell.org/ghc/ghc/-/issues/12479}{fix} necessary to
  26 make soon-to-be-released GHC 8.0.2 work on macOS Sierra.
  27
  28 Almost 1500 commits were made to the \texttt{master} branch by
  29 \href{https://gist.github.com/23Skidoo/1a291fd56a18b51f415db5fbaff56ec6}{53
  30 different contributors} since the 1.24 release. Among the highlights are:
  31
  32 \begin{compactitem}
  33 \item
  34   \href{http://cabal.readthedocs.io/en/latest/developing-packages.html#library}{Convenience,
  35     or internal libraries} -- named libraries that are only intended
  36   for use inside the package. A common use case is sharing code
  37   between the test suite and the benchmark suite without exposing it
  38   to the users of the package.
  39
  40 \item Support for
  41   \href{http://cabal.readthedocs.io/en/latest/developing-packages.html#foreign-libraries}{foreign
  42     libraries}, which are Haskell libraries intended to be used by
  43   foreign languages like C.  Foreign libraries only work with GHC 7.8
  44   and later.
  45
  46 \item Initial support for building Backpack packages. Backpack is an
  47   exciting new project adding an ML-style module system to Haskell,
  48   but on the package level. See
  49   \href{https://github.com/ezyang/ghc-proposals/blob/backpack/proposals/0000-backpack.rst}{here}
  50   and \href{http://blog.ezyang.com/category/haskell/backpack/}{here}
  51   for a more thorough introduction to Backpack.
  52
  53 \item \texttt{./Setup configure} now accepts an argument
  54   \href{https://github.com/ghc-proposals/ghc-proposals/pull/4}{specifying
  55     the component to be configured}. This is mainly an internal
  56   change, but it means that \texttt{cabal-install} can now perform
  57   component-level parallel builds (among other things).
  58
  59 \item A lot of improvements in the \texttt{new-build} feature
  60   (a.k.a. nix-style local builds). Git \texttt{HEAD} version of
  61   \texttt{cabal-install} is now recommended if you use
  62   \texttt{new-build}. For an introduction to \texttt{new-build}, see
  63   \href{http://cabal.readthedocs.io/en/latest/nix-local-build-overview.html}{this
  64     chapter} of the manual.
  65
  66 \item Special support for the Nix package manager in
  67   \texttt{cabal-install}. See
  68   \href{http://cabal.readthedocs.io/en/latest/nix-integration.html}{here}
  69   for more details.
  70
  71 \item \texttt{cabal upload} now uploads a package candidate by
  72   default. Use \texttt{cabal upload -{}-publish} to upload a final
  73   version. \texttt{cabal upload -{}-check} has been removed in favour
  74   of package candidates.
  75
  76 \item
  77   \href{http://cabal.readthedocs.io/en/latest/nix-local-build.html#cfg-field-index-state}{An
  78     \texttt{-{}-index-state} flag} for requesting a specific version
  79   of the package index.
  80
  81 \item \href{https://github.com/haskell/cabal/pull/3818}{New \texttt{cabal reconfigure} command}, which re-runs
  82   \texttt{configure} with most recently used flags.
  83
  84 \item
  85   \href{http://cabal.readthedocs.io/en/latest/developing-packages.html#autogenerated-modules}{New
  86     \texttt{autogen-modules} field} for modules built automatically
  87   (like \texttt{Paths\_PACKAGENAME}).
  88
  89 \item
  90   \href{http://cabal.readthedocs.io/en/latest/developing-packages.html#pkg-field-build-depends}{New
  91     version range operator} \texttt{\^{}>=}, which is equivalent to
  92   \texttt{>=} intersected with an automatically-inferred major version
  93   bound. For example, \texttt{\^{}>= 2.0.3} is equivalent to \texttt{>=
  94     2.0.3 \&\& < 2.1}.
  95
  96 \item
  97   \href{http://cabal.readthedocs.io/en/latest/installing-packages.html#cmdoption-setup-configure--allow-newer}{An
  98     \texttt{-{}-allow-older} flag}, dual to \texttt{-{}-allow-newer}.
  99
 100 \item New Parsec-based parser for \texttt{.cabal} files
 101   \href{https://github.com/haskell/cabal/pull/3602}{has been merged},
 102   but not enabled by default yet.
 103
 104 \item \href{http://cabal.readthedocs.io/en/latest/}{The manual} has
 105   been converted to reST/Sphinx format, improved and expanded.
 106
 107 \item
 108   \href{https://www.well-typed.com/blog/2015/08/hackage-security-beta/}{Hackage
 109     Security} has been enabled by default.
 110
 111 \item A lot of bug fixes and performance improvements.
 112
 113 \end{compactitem}
 114
 115 \subsubsection*{Looking Forward}
 116
 117 The next Cabal/\texttt{cabal-install} versions will be released either
 118 in early 2017, or simultaneously with GHC 8.2 (April/May 2017). Our
 119 main focus at this stage is getting the \texttt{new-build} feature to
 120 the state where it can be enabled by default, but there are many other
 121 areas of Cabal that need work.
 122
 123 We would like to encourage people considering contributing to take a
 124 look at \href{https://github.com/haskell/cabal/issues/}{the bug
 125   tracker on GitHub} and the
 126 \href{https://github.com/haskell/cabal/wiki/Hackathon-2016}{Wiki},
 127 take part in discussions on tickets and pull requests, or submit their
 128 own. The bug tracker is reasonably well maintained and it should be
 129 relatively clear to new contributors what is in need of attention and
 130 which tasks are considered relatively easy. For more in-depth
 131 discussion there is also the
 132 \href{https://mail.haskell.org/mailman/listinfo/cabal-devel}{\texttt{cabal-devel}}
 133 mailing list.
 134
 135 \FurtherReading
 136 \begin{compactitem}
 137 \item Cabal homepage:\hfill\url{https://www.haskell.org/cabal/}\\
 138 \item Cabal on GitHub:\hfill\url{https://github.com/haskell/cabal}
 139 \end{compactitem}
 140 \end{hcarentry}