1. The easy but limited solution is that this code doesn't compile, because argumentProvider must have a single type/effect and you couldn't have both a pure and an impure function with that type/effect.
2. Is purity that important? Ultimately we care about avoiding our programs doing unintended things, and often effects are just fine as long as they don't misbehave in some way. Purity is a means to an end.
3. It's fascinating to extend the ideas of generic programming from mainstream type systems to effect systems. I suspect there is a lot of potential benefit to be had if we can figure out how to do this without introducing a lot of boilerplate code, in the same way that we can write code using generic types to various degrees today but have type inference spare us a lot of keyboard bashing.
That's an interesting case I hadn't seen before, so thanks for the link.
Some of the related pages don't seem to be available at the moment, but from what I could see it looks as if that approach still gets hung up on questions of decidability, and doesn't have a very powerful concept of the regions where effects apply, which has been another interesting aspect of the wider research so far. It's good to see someone else working on the field, though.
Food for thought:
1. The easy but limited solution is that this code doesn't compile, because argumentProvider must have a single type/effect and you couldn't have both a pure and an impure function with that type/effect.
2. Is purity that important? Ultimately we care about avoiding our programs doing unintended things, and often effects are just fine as long as they don't misbehave in some way. Purity is a means to an end.
3. It's fascinating to extend the ideas of generic programming from mainstream type systems to effect systems. I suspect there is a lot of potential benefit to be had if we can figure out how to do this without introducing a lot of boilerplate code, in the same way that we can write code using generic types to various degrees today but have type inference spare us a lot of keyboard bashing.