[Haskell-beginners] Confused by the qualified imports

Hi, I was looking into Gloss examples for usage of Repa arrays. For example the Snow example (http://code.ouroborus.net/gloss/gloss-stable/gloss-examples/raster/Snow/Main...). What I do not get is that there is qualified import of the Repa package, but the "Z" and ":." are used without the prefix. When I some times accidentally omit the prefix the ghc always yell at me. What em I missing? Thanks, Libor