That's not what they mean there. You're confusing the evaluation of an expression to its value, with the execution of that value when the value is an IO a. In x

That's not what they mean there. You're confusing the evaluation of an expression to its value, with the execution of that value when the value is an IO a. In x >> y, you can evaluate x and y in whatever order, but the program x >> y denotes always runs the program x denotes before the program y denotes. Similar to how in [x,y], x always comes before y in the list order, even if you evaluate y first.