CODEWITHSUNDEEP
haskellcabalhaskell-stackbuild-dependencieshackage
accraze
accraze

Reputation: 1542

Remove Stack/Cabal packages and install older versions

I'm new to Haskell and am using Stack to build a small personal project on Mac OSX. I've recently added some new build-deps to my cabal file but now when I run stack build, I get the following error:

--  While attempting to add dependency,
    Could not find package api-builder in known packages

--  Failure when adding dependencies:
      api-builder: needed (==0.11.0.0), not present in build plan (latest applicable is 0.11.0.0)
      http-client: needed (==0.4.20), 0.4.27 found (latest applicable is 0.4.20)
      http-types: needed (==0.8.6), 0.9 found (latest applicable is 0.8.6)
    needed for package: music-haskell-0.1.0.0

Recommended action: try adding the following to your extra-deps in /Users/.../src/music-haskell/stack.yaml
- api-builder-0.11.0.0

You may also want to try the 'stack solver' command

When I run stack solver I get an error about the http-types package

cabal: Could not resolve dependencies:
trying: music-haskell-0.1.0.0 (user goal)
next goal: http-types (dependency of music-haskell-0.1.0.0)
rejecting: http-types-0.9 (conflict: music-haskell => http-types==0.8.6)
rejecting: http-types-0.8.6, 0.8.5, 0.8.4, 0.8.3, 0.8.2................
(global constraint requires ==0.9)
Dependency tree exhaustively searched.

From what I understand, it looks like I already installed http-types-0.9 but now I need http-types-0.8.6. I initially tried to install it manually with $stack install http-types, but I got the following error:

Error parsing targets: Specified target version 0.8.6 for package http-types does not match snapshot version 0.9

When I looked to see if I could do $ stack uninstall but it looks like that is deprecated.

How can I get rid of the snapshot/global target for http-type??

Upvotes: 2

Views: 826

Answers (1)

Michael Snoyman
Michael Snoyman

Reputation: 31315

You can override a specific snapshot package in your stack.yaml file via extra-deps, e.g.:

extra-deps:
- http-types-0.8.6

Once you start including packages that have conflicting version bounds versus the snapshot you're using, you can end up running into these problems pretty quickly. My recommended solution is:

  • Ask package maintainers to get their packages into Stackage so that you don't have to fiddle with the versions manually
  • Stick to packages in Stackage whenever possible

You can add a package to Stackage yourself, even if you're not the author. For instructions, see the maintainer guide.

Upvotes: 3

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