Creighton Hogg wrote:
x is a String, getLine has type IO String. That's what I was getting at in one of my last e-mails.
Hmm... let's see if I understand: * getLine() has type IO String. * The <- will "convert" an IO String to a plain String * So if I do x <- getLine() then x has the type String. So, the <- effectively ammounts to an IO a -> a conversion. In another email John Hughes said that one could think of "IO a" as a set of instructins for obtaining a. I guess that means that IO is a sort of imperative layer that helps the purely functional code interact with the outside world. So I can have an IO bit (e.g. a do-block) that calls functions (which are purely functional code) but I can't have a function that executes any IO. For example, it is not possible to write a function "my_read_file" that could work like this: my_data = my_read_file("my_file.txt") Correct? Otherwise this would be a function that is not referentially transparent. Cheers, Daniel. -- /\/`) http://oooauthors.org /\/_/ http://opendocumentfellowship.org /\/_/ \/_/ I am not over-weight, I am under-tall. /