[davery22]

Algebraic effects are in delimited continuation territory, operating on the program stack. No amount of monad shenanigans is going to allow you to immediately jump to an effect handler 5 levels up the call stack, update some local variables in that stack frame, and then jump back to execution at the same point 5 levels down.

[tome]

Quite the opposite, that's exactly what continuation monads do, for example `ContT`, and more structured versions such as `freer`. Those essentially simulate a stack rather than using the actual RTS stack. For the latter there are `eff` and `bluefin-algae` (the latter very much work in progress). So yes, in Haskell at least, monads are the right API for deli meted continuations.

https://www.stackage.org/haddock/lts-23.15/transformers-0.6....

https://hackage.haskell.org/package/freer-0.2.4.1

https://github.com/lexi-lambda/eff

https://hackage.haskell.org/package/bluefin-algae

[grg0]

That sounds like a fucking nightmare to debug. Like goto, but you don't even need to name a label.

[cryptonector]

> Like goto, but you don't even need to name a label.

That's what exceptions are.

But effects don't cause you to see huge stack traces in errors because the whole point is that you provide the effect and values expected and the code goes on running.

[AdieuToLogic]

>> Like goto, but you don't even need to name a label.

> That's what exceptions are.

In many contexts I agree. However, the difference here is exceptions are one-way execution control transfers.

Remember what was originally said:

  No amount of monad shenanigans is going to allow you to 
  immediately jump to an effect handler 5 levels up the call 
  stack, update some local variables in that stack frame, and 
  then jump back to execution at the same point 5 levels down.

Jumping "5 levels up the call stack", modifying some state, then jumping back "5 levels down" is to me pretty much the definition of a nightmare to reason about.

[vkazanov]

Well, you test the fact that the handler receives the right kind of data, and then how it processes it.

And it is useful to be able to provide these handlers in tests.

Effects are AMAZING

[agumonkey]

clos condition system is said to be just that, people seem to like it

also this kind of non local stack/tree rebinding is one way to implement prolog i believe