You won't find :: and => in Hoogle because they're keywords, not functions. For keywords, see the the wiki page that gtani posted:

http://haskell.org/haskellwiki/Keywords

I recommend reading Learn You a Haskell instead; the keywords were second nature to me by the time I finished.

I agree that there's too much "symbol soup" Haskell out there that uses infix functions excessively. Even if you recognize all of the functions, you still need to have their precedences memorized to decode the soup.