cabal-bounds
============

A command line program for managing the bounds/versions of the dependencies in a cabal file.

`cabal-bounds` is able to do two things:
* drop the bounds of the dependencies in the cabal file
* update the bounds of the dependencies in the cabal file using the cabal build information

Example: Raise the upper Bounds
===============================

If you have several cabalized projects, then it can be quite time consuming to keep the
bounds of your dependencies up to date. Especially if you're following the [package versioning policy](<http://www.haskell.org/haskellwiki/Package_versioning_policy>),
then you want to raise your upper bounds from time to time, to allow the building with newer
versions of the dependencies.

`cabal-bounds` tries to automate this update process to some degree. So a typical update process might look like:

    # update the version infos of all libraries
    $> cabal update

    # drops the upper bound of all dependencies in 'myproject.cabal', most likely you want to ignore 'base'
    $> cabal-bounds drop --upper --ignore=base myproject.cabal

    # create a cabal sandbox for building of 'myproject'
    $> cabal sandbox init
      
    # build 'myproject'
    $> cabal install

    # update the upper bound of all dependencies in 'myproject.cabal' by the cabal build information
    $> cabal-bounds update --upper --ignore=base myproject.cabal dist/dist-sandbox-*/setup-config 

Example: Bound Changes
======================

The `=>` shows what the result is of the operation for every dependency. Left is the dependency before
calling the command, right the one after calling.

    $> cabal drop myproject.cabal
    lens >=4.0.1 && <4.1   =>   lens

    $> cabal drop --upper myproject.cabal
    lens >=4.0.1 && <4.1   =>   lens >=4.0.1

If the cabal build (the setup-config) uses `lens 4.1.2`, then the results of the `update` command would be:

    $> cabal update myproject.cabal setup-config
    lens >=4.0.1 && <4.1   =>   lens >=4.1.2 && <4.2
    lens                   =>   lens >=4.1.2 && <4.2

    $> cabal update --lower myproject.cabal setup-config
    lens >=4.0.1 && <4.1   =>   lens >=4.1.2
    lens <4.1              =>   lens >=4.1.2
    lens                   =>   lens >=4.1.2

    $> cabal update --upper myproject.cabal setup-config
    lens >=4.0.1 && <4.1   =>   lens >=4.0.1 && <4.2
    lens >=4.0.1           =>   lens >=4.0.1 && <4.2
    lens                   =>   lens >=4.1.2 && <4.2

Installation
============

You have to ensure, that the `Cabal` library of `cabal-bounds` matches the one used by the `cabal` binary:

    $> cabal --version
    cabal-install version 1.18.0.2
    using version 1.18.1 of the Cabal library 

    $> cabal install --constraint="Cabal == 1.18.1" cabal-bounds

If you update the `cabal` binary and the used `Cabal` library changes, then you have to rebuild `cabal-bounds`.

Command Line Usage
==================

    $> cabal-bounds --help
    cabal-bounds [COMMAND] ... [OPTIONS]
      A command line program for managing the bounds/versions of the dependencies
      in a cabal file.
    
    Common flags:
      -O --only=ITEM             Only the bounds of the dependency are modified.
      -I --ignore=ITEM           This dependency is ignored, not modified in any
                                 way.
      -o --outputCabalFile=ITEM  Save modified cabal file to file, if empty, the
                                 cabal file is modified inplace.
      -h --help                  Display help message
      -v --version               Print version information
    
    cabal-bounds drop [OPTIONS] CABAL-FILE
    
      -U --upper                 Only the upper bound is dropped, otherwise both
                                 - the lower and upper - bounds are dropped.
      -l --library               Only the bounds of the library are dropped.
      -e --executable=ITEM       Only the bounds of the executable are dropped.
      -t --testsuite=ITEM        Only the bounds of the test suite are dropped.
      -b --benchmark=ITEM        Only the bounds of the benchmark are dropped.
    
    cabal-bounds update [OPTIONS] CABAL-FILE SETUP-CONFIG-FILE
    
      -L --lower                 Only the lower bound is updated.
      -U --upper                 Only the upper bound is updated.
      -l --library               Only the bounds of the library are updated.
      -e --executable=ITEM       Only the bounds of the executable are updated.
      -t --testsuite=ITEM        Only the bounds of the test suite are updated.
      -b --benchmark=ITEM        Only the bounds of the benchmark are updated.

Issues
======

Perhaps the currently most annoying thing is, that you have to live with the reformating of your
`cabal` file done by the pretty printer of the `Cabal` library.

To reformat your `cabal` file without changing any bounds you can call `cabal-bounds` with the name of
a section that isn't present in the `cabal` file:

    $> cabal-bounds drop --executable=blub myproject.cabal