> The bad part is that most of C/C++-compatible HLS tools are proprietary, and open source ones are either Scala-based (Chisel, SpinalHDL) or seem to be academic toy projects.
I think the article author is mixing up HLS tools and HDLs. HLS tools convert some subset of C to a hardware implementation, and thought that Chisel/SpinalHDL were converting Scala to hardware. But they are really just HDLs implemented as a DSL within Scala, much like Migen uses Python but does not execute Python code on the FPGA.
Scala has a history of embedded domain specific languages that are difficult to understand. (Rather like Perl now that I think about it.) This is not universal in scala EDSLs but definitely exists. So it's a fair concern in general. IMO Chisel is a nice EDSL so, in this context, the concern is unwarranted.
Nice! I used it in college and took a liking to it, it was pretty easy to write a full multi core riscV processor with mmu/etc even as my first exposure to hardware design.
The compile times were killer though. Has much progress been made there?
Why is Scala a problem?