tokens: One major difference between Haskell 's type system and that of most OO languages is that the ability for a function to have side effects is represented by a data type ( a monad such as IO ) .
ner_tags: O O O O B-Language O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Data_Type O O B-Data_Type O O