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Comment by solomonb | Hacker News Reader

`eff` is a research project that is no longer in active development and never made it to production in any sense. It would be AMAZING if `eff` were completed but I dont think that will happen at this point.

`eff` is based on delimited continuations (which Alexis had to build into GHC), it is not using `Freer`. If you want to look at an effect system in Haskell that actually has been used in production AND is based on this paper then look at `freer-simple`: https://hackage.haskell.org/package/freer-simple

No it is not high performance, but neither are any other Haskell effect systems and performance is relative to your problem domain. It also has the benefit of being implemented very similarly to Oleg's paper making it a lot easier to learn from then most other options.

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> No it is not high performance, but neither are any other Haskell effect systems

This is not true. IO-wrapper effect systems (in practice, effectful or Bluefin) have as good performance as Haskell's IO monad, that is to say as good as you can get in Haskell.

Yes but from what I understand at a loss of safety. You can decide if that is worth it but you aren't getting a free lunch.

that said, your library is really cool. : )

No, no loss of safety. Was there something in particular you were thinking of? With IO-wrapper effect systems you give up native multishot continuations (but you can always get them back by wrapping in LogicT).

You can look at my table of "A Comparison of Effect Systems at a Glance" to see all the tradeoffs:

https://hackage-content.haskell.org/package/bluefin-0.2.0.0/...

> your library is really cool. : )

And thanks! Glad you like it. Feel free to reach out to me at any time if you'd like any help with it or have any questions or comments.

> No, no loss of safety. Was there something in particular you were thinking of?

This is second hand information and may apply more so to effectful then bluefin. I have just done some pretty minimal test projects with bluefin and effectful but I was told:

""" It's not too hard to make segfault if you organize your higher order effects just right.

It's been a while but i think you just return a continuation with the effect you just handled, and then all of a sudden it's not in scope and yet you need to still handle it.

And the tricks they use to make things go fast don't work in this case and things go boom """

That definitely doesn't apply to Bluefin. I can't rule out it applying to effectful, but it is careful to do dynamic checks to make sure you can't use effects in the wrong scope. Maybe you're thinking of eff (i.e. what started this thread)? Alexis King described how to get it to segfault in this video: https://www.twitch.tv/videos/1163853841 (now private, sadly).

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