How to link the local version of the library with cabal

Question

I want to make a local change in Pandoc and recompile Hakyll so that it uses this local change. So, I downloaded the version for developing both libraries:

 git clone https://github.com/jgm/pandoc.git git clone https://github.com/jaspervdj/hakyll.git 

Then I made the changes to Pandoc that I wanted and then installed using

 cd pandoc cabal install 

I tested with install Pandoc that it works as expected.

Now I want Hakyll take these changes. So i tried

 cd hakyll cabal install 

Now Hakyll starts reinstalling Pandoc and gets the new version from Hackage (I think), thereby overriding the local changes that I made in Pandoc . How can I convince cabal use a locally installed version of Pandoc and not reinstall it?

Answer 1

I realized that by default pandoc builds with the old version of blaze-html , and Hakyll requires blaze-html 1.5 . Rebuild pandoc with

 cabal install -fblaze_html_1_5_0 

then Hakyll will not reinstall pandoc .