22 Mar
2011
22 Mar
'11
3:19 p.m.
I have to admit I really do not like having Applicative and MonadPlus with different behavior. Yes, one is redundant, but that is more an artifact of language evolution, than an intentional opportunity for diverging behavior. Every library I am aware of to date, save of course this one, has maintained their compatibility.
Another way of thinking about it is that for the different behaviours to be useful, a programmer has to know about them and intentionally use one or the other. And then the person reading it later has to be aware of that difference and keep in mind the different behaviour implied by the use of different classes. That's a pretty subtle thing to have to be aware of.