Salut, Laurent. Not for a long time has it been like that in my experience. I am on MacOS Sierra, but it's been darwin for as long as I can remember.
$ perl -E 'say $^O'
darwin
$ perl -v
This is perl 5, version 26, subversion 1 (v5.26.1) built for darwin-2l
+evel
$ uname -a
Darwin MYHOSTNAME 16.7.0 Darwin Kernel Version 16.7.0: Thu Jun 21 20:0
+7:39 PDT 2018; root:xnu-3789.73.14~1/RELEASE_X86_64 x86_64
See Re: Get macOS Version for recent discussion.
The way forward always starts with a minimal test.