On Thursday, 10 October 2019 at 08:59:49 UTC, Russel Winder wrote:

> I feel that it is best to leave functional programming to functional programming language, e.g. Haskell, Scheme, etc. rather than try to do functional programming in imperative languages, e.g. Java, C++, Rust, D. The reason is things like lazy evaluation and the consistency of everything being a function, etc. The underlying computational models of functional programming languages and imperative programming languages need different mindsets to use well. Witness the issues in using Scala.

My impressions is that the complaints about Scala are similar to C++: too many features that clash with one another and make the language complicated, plus extremely slow compilation times. I haven't seen a lot of complaints about mixing imperative and functional.

On Thursday, 10 October 2019 at 16:05:13 UTC, bachmeier wrote:
> On Thursday, 10 October 2019 at 08:59:49 UTC, Russel Winder wrote:
>
> My impressions is that the complaints about Scala are similar to C++: too many features that clash with one another and make the language complicated, plus extremely slow compilation times. I haven't seen a lot of complaints about mixing imperative and functional.

Scala compile times are slow, because Scala has more compilation phases than C++. I guess that is because of feature bloat in the language as such, IMHO not necessarily because FP and OOP are mixed into the same language. Scala is just packed with too many language constructs that are also in many cases quite extensive. Then there is a problem with implicit conversions in Scala not being scalable in compilation times, see https://dzone.com/articles/implicits-scala-conversion

In Scala3 (due to be released in spring 2020) implicits were replaced by what they call delegates (and extension methods were introduced). Whether that reduces compilation times I don't know. But the compiler in Scala3 is based on a complete new approach to further reduce compilation times. However, Scala3 is a new language. Whether people will make the move from Scala to Scala3 remains to be seen.