[Haskell-beginners] Unicode characters in function names: some don't work?

Hi! say I wanna use "—" as new infix operator: it's the big dash used a bit like parenthesis, especially at the end of sentences —like this. in ghci directly: Prelude> let (—) a b = a + b No problem, is accepted and usable. Same in files. Now I try using (»), a French (amongst others) punctuation sign, typically replaces the quote-ends, « like this ». Doesn't work: <interactive>:2:6: lexical error at character '\187' I thought Haskell was Unicode-friendly? Why some symbols but not others? :'(