I agree Haskell has had an important influence, but I don't see why people would necessarily "go directly" to it because of that. In fact, I would argue just the reverse. People chose the derivative languages b/c they provide things the original does not.
To wit, Lisp never became mainstream despite exerting a huge influence. Likewise Smalltalk.
Technically true, but I don't think it makes sense to consider Clojure to be the same thing as Lisp in the context of ternaryoperator's statement (though I obviously can't speak for him). Notably, Clojure's tight integration with Java is the primary reason for its relative popularity, and what most sets it apart from the rest of the Lisp family. It is disingenuous to claim Clojure means Lisp has gone mainstream when the popularity of Clojure is not due to its inclusion in the Lisp family.
Beyond that, I'm not quite sure Clojure counts as "mainstream" yet. According to the TIOBE Index, it doesn't even rank in the top 50 languages. Heck, the top 20 includes R, and Dart, neither of which I would call "mainstream" (I'm actually really surprised at how high R is ranking). I don't know how significant that is, though the TIOBE Index is measuring "number of skilled engineers world-wide, courses, and third party vendors" and that seems like a reasonable approximation for "mainstream" to me.
There are several languages targeting the JVM these days. And, what obviously sets Clojure apart from other JVM languages is its Lispiness (i.e., the JVM is constant across JVM languages).
Clojure is not married to the JVM either-- in fact, it has been hinted that it would jump ship if something better comes along or the current situation becomes less viable. Furthermore we already have a dialect of Clojure called ClojureScript which targets JavaScript/node/V8.
And, I look at the JVM as really merely a library/API/runtime. C++ has STL and stdio and such and they are not part of the language proper but rather merely libraries for interacting with the underlying operating system (in a platform independent way). The same is true for the JVM with respect to Clojure and Scala et al.
Yeah, but nothing in it is Smalltalk-specific. It's not like Smalltalk survives in the mainstream because of Hotspot (in the way that, say, Algol survives).
Well, a counter point then can be: and why did those vendors did not insist on Smalltalk? Why weren't Smalltalk more heavily pushed by some big vendor itself?
It's not like SUN was the only player in town. IBM pushed Smalltalk IIRC.
I think this (from StackOverflow) tells a more comprehensive story):
• when Smalltalk was introduced, it was too far ahead of its time in terms of what kind of hardware it really needed
• In 1995, when Java was released to great fanfare, one of the primary Smalltalk vendors (ParcPlace) was busy merging with another (Digitalk), and that merger ended up being more of a knife fight
• By 2000, when Cincom acquired VisualWorks (ObjectStudio was already a Cincom product), Smalltalk had faded from the "hip language" scene
To wit, Lisp never became mainstream despite exerting a huge influence. Likewise Smalltalk.