Tony Morris

But your reasoning is wrong. It's not trading anything. It's throwing away, for no benefit.

Ah I see, I agree with you. But instead of pretending people will follow guidelines I rather use a language that makes it mandatory

That's why I rather write my code in Haskell instead of having half assed effect tracking in Scala

There is a good reason to not write IO in Scala. This reason is not one of them. It's not good reasoning.

What would be the good reason to not write IO in Scala then, except the obvious performance hit ?

The same reasoning writing anything in Scala is a bad idea. IO takes more than a performance hit. It's untenable.

I acknowledged the reasoning part. But it seems you agree with me on the big picture unless I misunderstand you

"Don't write IO in Scala. Don't write anything in Scala." IO in Scala is just as safe as it is in Haskell. Reasoning otherwise is busted.