Stack: Detect unused dependencies

Created on 19 May 2015 · 9Comments · Source: commercialhaskell/stack

Would be nice. Based on whatever code we're using to detect dependencies for the setup code, we could use that to detect what's _not_ being used to aid in cleaning up dependencies.

awaiting pull request help wanted enhancement

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chrisdone

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Here's a cool project that does this: https://github.com/afcady/packunused

Perhaps it could be integrated with stack? It does need to be compiled with the version of Cabal used in the user's project, though (whereas stack does not need to be compiled with the same Cabal version).

mgsloan on 5 Feb 2016

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About this. One idea that's come to mind is for Setup and possibly other modules keep a listing of all projects that use stack. Then a "garbage collect" could check items in the listing to see if they still exist. The listing could then be used to determine what stays, and everything else goes.

DanBurton on 20 May 2015

As noted in #1667, it would be good to involve this check in sdist / upload.

mgsloan on 19 Jan 2016

Here's a cool project that does this: https://github.com/afcady/packunused

mgsloan on 5 Feb 2016

👍2

Perhaps it could be integrated with stack? It does need to be compiled with the version of Cabal used in the user's project, though

@mgsloan Is that really the case? It seems to me that you just have to compile with -ddump-minimal-imports and then packunused picks up the (text format) outputs, or am I misunderstanding?

There also does seem to be support for stack, e.g. packunused --help from https://github.com/hvr/packunused/pull/23 prints:

In order to use this tool you should set up the package to be analyzed as
follows, before executing 'packunused':

For stack:  stack clean
            stack build --ghc-options=-ddump-minimal-imports
            packunused

Only problem with GHC 8: https://ghc.haskell.org/trac/ghc/ticket/12474

nh2 on 8 Aug 2016

@mgsloan Is that really the case? It seems to me that you just have to compile with -ddump-minimal-imports and then packunused picks up the (text format) outputs, or am I misunderstanding?

Could be! Worth giving it a try. I just saw that it's using lots of stuff from Cabal, and figured that the versions would need to match

mgsloan on 8 Aug 2016

The GHC ticket, and packunused were both fixed.

nh2 on 4 Oct 2016

Trying to move this one along via https://github.com/hvr/packunused/issues/27.