cabal-bounds

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

cabal-bounds is able to do these things with the bounds of the dependencies in the cabal file:

• drop them
• update them by the library versions of the current cabal build
• update them by the library versions of a haskell platform release
• update them by the library versions specified by a file
• dump the libraries/dependencies and their lower bound versions from the cabal file(s) into a file

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, 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: Update Bounds by Haskell Platform

Ensuring that your project builds with the current haskell platform - or perhaps the last two ones - can make it, especially for beginners, a lot easier to build your project.

cabal-bounds supports the updating of the bounds by the library versions of a specific haskell platform release.

To update the bounds to the haskell platform 2013.2.0.0:

$> cabal-bounds update --haskell-platform=2013.2.0.0 myproject.cabal

There're two additional symbolic names for specifying a haskell platform release: current and previous.

So one use case might be to initialize the bounds to library versions used by a haskell platform release, test if your project builds and works with these, and then raise the upper bounds to the newest available versions:

# intialize the bounds to the previous haskell platform release
$> cabal-bounds update --ignore=base --haskell-platform=previous myproject.cabal

# build and test the project

# initialize the lower bounds of libraries not present in the haskell platform
$> cabal-bounds update --lower --missing --ignore=base myproject.cabal dist/dist-sandbox-*/setup-config

# drop the upper bounds to test your project with the newest available library versions
$> cabal-bounds drop --upper --ignore=base myproject.cabal

# build and test the project

# set the upper bounds to the ones used in the current build
$> cabal-bounds update --upper --ignore=base myproject.cabal dist/dist-sandbox-*/setup-config

If you specify a haskell platform release and a setup config file at once, then the setup config library verions are only used for the libraries not present in the haskell platform release.

Example: Update Bounds by File

It's also possible to update the bounds by library versions specified in a file:

$> cabal-bounds update --fromfile=libs.hs myproject.cabal

The libs.hs file has to be of the format:

[ ("libA", [0,2,1]), ("libB", [2,1]), ("libC", [1]) ]

If you specify a library file, a haskell platform release and a setup config file at once, then first the haskell platform libraries and versions are considered, then the library file and at the end the setup config file.

The library file can be created by the dump command:

$> cabal-bounds dump --output=libs.hs myproject.cabal

The dump command will dump dependencies with their lower bound version. The command can take multiple cabal files. If the same dependencies is present in multiple files, then the lowest lower bound version is taken.

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-bounds drop ...
lens >=4.0.1 && <4.1   =>   lens

$> cabal-bounds drop --upper ...
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-bounds update ...
lens >=4.0.1 && <4.1   =>   lens >=4.1.2 && <4.2
lens                   =>   lens >=4.1.2 && <4.2

$> cabal-bounds update --lower ...
lens >=4.0.1 && <5     =>   lens >=4.1.2 && <5
lens >=4.0.1 && <4.1   =>   lens >=4.1.2
lens <4.1              =>   lens >=4.1.2
lens                   =>   lens >=4.1.2

$> cabal-bounds update --upper ...
lens >=4.0.1 && <4.1   =>   lens >=4.0.1 && <4.2
lens >=4.0.1           =>   lens >=4.0.1 && <4.2
lens                   =>   lens <4.2

You can also specify which component of the version number should be updated:

$> cabal-bounds update --lowercomp=minor ...
lens >=4.0.1 && <4.1   =>   lens >=4.1.2

$> cabal-bounds update --lowercomp=major2 ...
lens >=4.0.1 && <4.1   =>   lens >=4.1

$> cabal-bounds update --lowercomp=major1 ...
lens >=4.0.1 && <4.1   =>   lens >=4 && <4.1

$> cabal-bounds update --uppercomp=minor ...
lens >=4.0.1 && <4.1   =>   lens >=4.0.1 && <4.1.3

$> cabal-bounds update --uppercomp=major2 ...
lens >=4.0.1 && <4.1   =>   lens >=4.0.1 && <4.2

$> cabal-bounds update --uppercomp=major1 ...
lens >=4.0.1 && <4.1   =>   lens >=4.0.1 && <5

Options

You can restrict the modification to certain sections in the cabal file by specifing the type and the name of the section:

• --library
• --executable=name
• --testsuite=name
• --benchmark=name

If you omit these options, then all sections are considered and modified.

You can also restrict the modification of dependencies by specifing which dependencies should only or shouldn't be modified:

• --only=name
• --ignore=name

You can also only update the dependencies without a bound by specifying the --missing flag. If you omit these options, then all dependencies are considered and modified.

All options taking a name can be specified multiple times: e.g. --executable=exe1 --executable=exe2 or --ignore=base --ignore=whatever

Please consult cabal-bounds --help for a complete list of options.

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.

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