Copying the colours used by one major mode to another

[Jim Burton]

Hi, I want to customize one major mode to use the same colours as
another. Both of these modes are for editing source code (Agda and
Haskell, respectively), the second mode being much more readable with
dark themes. I want to do this locally, i.e. in ~/.emacs, and hoped
there was an easy way to do it without copying lots of properties by
hand. Is there an easy way to do this?  What are the hard ways?

Thanks,

-- 
Jim