Haskell Stack install package dependency from github

Question

Is it possible to install a version of a package from github using Haskell stack?

e.g. in a .cabal or a stack.yaml file, how can I point a depe

Answer 1

New syntax for Stack >1.7.1

As @Flip commented, the docs at docs.haskellstack.org clarify the new syntax for your stack.yaml is: (note the full commit hash needs to be used)

extra-deps:
- github: apolishch/prime_table
  commit: a510622a824af999a809191e8c959b8ea5fa8bdb
- github: apolishch/reactive-banana
  commit: 74bac0f86ed172f95bb6f6a31041992fc161cf79
  subdirs: reactive-banana

To be clear: dependencies in your stack.yaml make sure that the packages (which are not in Stackage) are available would some .cabal file in your project want them, just in case.

You still have to specify the name of the package in build-depends in your .cabal file to say you actually depend on the package.

Note it doesn't matter what branch the commit is on, and repos can be forks. When a package is in a subdirectory, you can specify it, otherwise it will default to top-level.

Syntax for Stack >1.6.0

extra-deps:
- github: git@github.com:apolishch/prime_table.git
  commit: a510622a824af999a809191e8c959b8ea5fa8bdb

[Edit] I have found that sometimes the syntax from 1.7.1 fails with error message

C:\Users\username\AppData\Local\Programs\stack\x86_64-windows\ghc-8.4.3\lib/../mingw/bin\ar.exe: .stack-work\dist\7d103d30\build\objs-10648\libHSpackagename-0.1.0.0-DlGXqyeqb9MDn2z8KhgjVb.a: No such file or directory

and I solved that by using the 1.6.0 syntax, even though I was using Stack 1.7.1. When using Travis, that will fail because Travis can't clone via SSH without your SSH keys of course. But you can still use the https link as

extra-deps:
- github: https://github.com/apolishch/prime_table.git
  commit: a510622a824af999a809191e8c959b8ea5fa8bdb