The packunused package

[Tags:bsd3, program]

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-


Versions,,,,,,, 0.1.2
Dependencies base (>=4.5 && <4.7), Cabal (>=1.14 && <1.17), cmdargs (==0.10.*), directory (>=1.1 && <1.3), filepath (==1.3.*), haskell-src-exts (>=1.13 && <1.15) [details]
License BSD3
Author Herbert Valerio Riedel <>
Maintainer Herbert Valerio Riedel <>
Category Distribution
Home page
Source repository head: git clone
Uploaded Sun Oct 13 12:51:11 UTC 2013 by HerbertValerioRiedel
Distributions LTSHaskell:0.1.2, NixOS:0.1.2
Downloads 3188 total (43 in the last 30 days)
0 []
Status Docs available [build log]
Successful builds reported [all 1 reports]
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