> Every function with an IO interface cannot be reasoned about locally because of unexpected interactions with the io parameter input. This is particularly nast

> Every function with an IO interface cannot be reasoned about locally because of unexpected interactions with the io parameter input. This is particularly nasty when IO objects are shared across library boundaries. Isn't this just as true of any function using io in any other language? > As a library author, how do I handle an io object that doesn't behave as I expect? But isn't that the point of having an interface? To specify how the io object can and can't behave.