Would you say that people interested in languages should first look at certain "mainstream" languages Scheme/Racket, Common Lisp, Haskell, OCaml, Smalltalk, and Prolog, before looking at less-mainstream ones?
Lol nope, not gatekeeping programming languages :)
The above are all pretty cool though and each (as Larry Wall would put it) are the perfect examples of modernism. Each one takes a single idea to a fault.
Lisp => lists, Haskell => functions, Scheme => lists and recursion, Prolog => logic, Smalltalk => objects, Forth => concatenative and extreme minimalism, and APL => arrays.
Most post-modern languages combine many of the above in more practical and less elegant ways. Python is OO at heart, but can be written in a functional style, and can do array programming with Numpy.
So there is value (I think) to looking back at those languages from an educational point of view even if you're not using them in your personal projects or production.
The more novel ones that the author posted are probably also educational in their own way, but probably don't ram just one idea home. I think we're mostly past that now as Wall has stated. Perl6 might not run very fast or be very mature or popular, but it is a very interesting language that does a good job showing the post modern system. It pulls what the language designers felt were the best features from all the past languages (Perl5, Python, APL, Haskell, Smalltalk, Awk, Java, C#...etc).
That list of "modernism" languages has some bits of truth to it, but I think it's misleading to people who aren't already familiar with those languages, and "to a fault" sounds dismissive, and maybe discourages people from learning for themselves.
Perl is an interesting language (and I defended Perl's merits in a language forum within the last year [1]). But people who've mostly done Perl for a long time might want to question cute sayings about other languages, and discover that, today, for example, the evolution of Scheme (especially Racket) has different ways of doing those best features from other languages that you list for Perl6.
I do think "to a fault" is subjective, but things like Prolog make a great example. Prolog is really cool and useful, but it makes anything except for the queries a real nightmare and will therefore never takeoff as a general purpose language. That's all I'm trying to say. Languages like Perl allow you to do logic programming with logic programming libraries, but also make text processing a breeze.
Take it with a grain of salt of course. Smalltalk is amazing, but the way you store code in an image isn't for s everyone.
I don't understand your last paragraph...can you please elaborate? What cute sayings are you referring to?
I meant the cute saying about modernism and "to a fault".
I agree about Prolog being logic-only. (Though it was once included as the query language of the complex data model of a commercial CAD-like system I worked on.)
Now Scheme (not lists and recursion to a fault) and other languages have logic programming as library or language extension: https://en.wikipedia.org/wiki/MiniKanren
