io monad question

[luc]

i designed some basic functions, , mainly String -> [String], or similar with types, plus some more complex datatypes.   Up to now; i was testing them on a basic database I was creating in the core main, "by hand". Then i added a basic parser with happy; and bingo; my test database is now loaded from a file... as IO String..; huh!   after a second though; this makes sense, except that i have to change all the type of my functions; now IO String..   plus a few that just dont compile; and i cant understand why...   my question: I had to change most of my type of the functions.as is propagated through the code. (i.e. f need g; that need h; etc...) to add IO. is that kind of propagation normal, or can i Stop it somewhere ? how? is that because my functions just uses string as type ? and not data (ie type relation =string; instead data Relation String) can i design a function that will do IO String-> String, or IO String -> Data X, that will stop that IO propagation , through my code ? how can i handle function when my database is not IO, then ?   i suppose im not the first to ask. any link ? thread ? faq example would be welcomed...