Native support for OSX builds?

Currently if I specify language: haskell in the .travis.yml file and use osx as an operating system, I see the following error:

$ export TRAVIS_HASKELL_VERSION=$(travis_ghc_find '7.10.3')
No such ghc version '7.10.3'.
Using default ghc version '7.10.3'.
GHC 7.10.3 not found. Terminating.

See example of the build here:

I wonder, what can be done here?

You can suggest a pull request to which is where the logic whose output you gave is.