You can picture functions with the IO type as something to compose a program out of. This program is then run by runtime system of your implementation, and that

You can picture functions with the IO type as something to compose a program out of. This program is then run by runtime system of your implementation, and that's "when the byte is written". Here's a nice explanation of Haskell IO: http://stackoverflow.com/questions/13536761/what-other-ways-can-state-be-handled-in-a-pure-functional-language-besides-with/13538351#13538351 http://stackoverflow.com/questions/13536761/what-other-ways-...