monadic IO is basically a type of effect system. the big issue is that you have to do a LOT of complex shuffling of types and values in order to deal with effe

monadic IO is basically a type of effect system. the big issue is that you have to do a LOT of complex shuffling of types and values in order to deal with effects. You can actually avoid a ton of this by thinking about purity in a less expression-level way, like how Koka does it. And, I think I'd probably try implementikng something like it (or eff) in my language. You can always replicate laziness by making your own thunks. But this just isn't as convenient.