Earlier quoted context omitted.
I mean, if you want a direct quote from Lennart Augustsson, here's a quick transcription of the relevant parts of the relevant video. https://www.youtube.com/watch?v=hgOzYZDrXL0 > So strictness is really fantastic, I must say. Stack traces work. When something goes wrong, you can say "so you call things from there to there to there". It's the single most time saving thing from Mu compared to Haskell, because things d…
It seems we have have got a bit off track and my quite precise claims have got lost. My claims are that 1. It is incorrect to claim that "Laziness is very hard to get right in practice. ... It's the reason why ... Standard Chartered, uses their own Haskell compiler that's strict by default." 2. Rather, the reason Mu is strict is that it was designed to target an existing strict runtime (I offer this claim without pro…
> If my only concern was semantics (i.e., input-output behavior) then I'd prefer call-by-name semantics, because I think it behaves more compositionally. But for practical concerns like resource consumption, debugging, stack trace, etc then strict evaluation is better.
Overall though, you're right that my initial claims against strictness may have been a bit too harsh. If I could edit my initial comment, I would write something more like
> 2. Laziness is often hard to use in practice. As Standard Chartered, a company that uses a strict variant of Haskell, notes: space leaks, difficulty of debugging, and hard to decipher stack traces are downsides to laziness.
In my opinion, laziness definitely does have nicer semantics than strictness. It's more expressive and easier to compose. In practice though, I prefer strict languages mostly for the reasons Standard Chartered mentions.