[jorkadeen]

We think that functional programmers should be able to write e.g. `List.count(x -> x > 5, l)` (or e.g. use pipelines with |>) and have it run as fast as an ordinary imperative loop with a mutable variable. The Flix compiler gives them that-- but it requires the program to undergo certain transformations that may require expressions to be moved around and eliminated. It is dangerous to perform such optimizations with incorrect assumptions about types or effects. How to support that together with print-debugging is the challenge.

For systems in production, we have the `Logger` effect and associated handlers.

[vlovich123]

And yet modern optimizers don’t actually seem to have a problem with a transformation like that as you must know. Try list.iter().filter(|x| x>5).count() in Rust

And yes, Rust doesn’t have an effect system yet, but others have mentioned Haskell and how it handles tracing and logging and the limitations of effect systems interplaying with such things.

[jorkadeen]

It was a simple example; whether a specific optimization applies is very tricky. We have to look at the details. When can Rust move or eliminate a binder? Does Rust support automatic parallelization? What happens if you use unsafe blocks to lie to their type and ownership system? I think many of the same issues will surface.

To be me, the interesting question is: What happens when you lie to the type (and effect or ownership) system?