The packunused package

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This simple CLI tool allows to find out which of the packages listed as build-depends in a Cabal package description file are redundant.

packunused works by taking advantage of GHC's -ddump-minimal-imports feature which creates .import files for each compiled module containing a minimal set of explicit import declarations. These .import files together with Cabal's generated package configuration meta-data is analyzed by packunused to detect potentially redundant package dependencies.

In order to use packunused you have to configure the package as usual. See the example session below:

 cabal clean
 rm *.imports
 cabal configure -O0 --disable-library-profiling
 cabal build --ghc-option=-ddump-minimal-imports

The -O0 --disable-library-profiling options are just to speed up compilation. In some cases you might want to pass additional options to the configure step, such as --enable-benchmark or --enable-tests.

When run, packunused prints a report to standard output listing its findings for each component built. The following is an example for the packunused package itself, with a redundant dependency added for demonstration on purpose:

 detected package components

  - executable(s): packunused

 (component names suffixed with '*' are not configured to be built)


 The following package depencencies seem redundant:

  - criterion-


Dependenciesbase (>=4.5 && <4.8), Cabal (>=1.14 && <1.21), cmdargs (==0.10.*), directory (>=1.1 && <1.3), filepath (==1.3.*), haskell-src-exts (>=1.13 && <1.16) [details]
Copyright© 2014 Herbert Valerio Riedel
AuthorHerbert Valerio Riedel
MaintainerHerbert Valerio Riedel <>
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Source repositoryhead: git clone
UploadedSat Apr 26 15:25:19 UTC 2014 by HerbertValerioRiedel


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