[Haskell-beginners] How to load multiple source files in GHCi?

[Yang]

Hi,

     I have a few source files in current directory to load as modules 
of my library in GHCi. How should I do with :load command? I tried

ghci>:load a.hs

where module a is defined and exported for testing purpose, but failed for

a.hs:1:1:
     File name does not match module name:
     Saw: `Main'
     Expected: `a'
Failed, modules loaded: none.

However, I do not need Main to run for testing. I just want to test 
exported functions.

-- 
Best Regards
Yang Zhao