postgresql haskell haskell-stack persistent

Haskell Stack Persistent error, cannot find -llibpq

I have set up a project, which uses Servant and Persistent, using a PostgreSQL backed. Everything works fine, when I run stack ghci, including migration, but when I run stack build, I get the following error:

Linking .stack-work\dist\29cc6475\build\ServantAuthTraining-exe\ServantAuthTraining-exe.exe ...
C://Users//Chris//AppData//Local//Programs//stack//x86_64-windows//ghc-8.8.3//mingw//bin/ld.exe: cannot find -llibpq
collect2.exe: error: ld returned 1 exit status
`gcc.exe' failed in phase `Linker'. (Exit code: 1)

--  While building package ServantAuthTraining-0.1.0.0 using:
      C:\sr\setup-exe-cache\x86_64-windows\Cabal-simple_Z6RU0evB_3.0.1.0_ghc-8.8.3.exe --builddir=.stack-work\dist\29cc6475 build lib:ServantAuthTraining exe:ServantAuthTraining-exe --ghc-options " -fdiagnostics-color=always"   
    Process exited with code: ExitFailure 1

I am on windows, and very new to all of the mentioned techs.

I can connect to the database via pgAdmin.

Solution

You likely need to pass something like --extra-include-dirs=C:\PostgreSQL\8.4\include --extra-lib-dirs=C:\PostgreSQL\8.4\lib (or whatever path) to stack so it knows where to find libpq. This can also be configured in your stack.yaml as described at https://docs.haskellstack.org/en/latest/yaml_configuration/#extra-include-dirsextra-lib-dirs.