Hm, I'm not sure about the parallels between Lisp and Haskell, and the conclusion that they are primarily valued for showing off. Yes, they are appealing to programmers with that mentality because they are powerful languages that are difficult to learn and use effectively. However beyond that they diverge dramatically.
Lisp is a language with no syntax, it is like an unshaped lump of clay. It gives you total freedom to implement any computational construct you can imagine. This does allow greater productivity for very small teams, and maybe it's the most powerful tool for the smartest programmer, however it doesn't offer anything to improve the practice of maintenance and reuse. This is why no viable ecosystem ever coalesced around Lisp, and in fact why there are so bloody many Lisps to begin with: because it is attractive primarily to individuals who want to build their own special flower.
Haskell gains its power in an almost opposite way by its type system, it's an extremely rigid structure which contributes tremendously to code reuse and maintainability. It works because great effort was put into the type inference so that it is strong yet lightweight.
IMHO as a seasoned programmer who has spent 5+ years and 7+ years on individual projects, I can definitely see that Haskell is addressing real world problems in a way that Lisp can not. I use ruby day to day, and frankly it's good enough in its meta-programming ability to solve most of the pain that Lisp solves compared to say Java or C++. However when I look at the problems which creep in over a period of years, the code rot, these are things which Haskell trivially prevents while half-hearted type systems like Java don't really put a dent in.
I think the reason Haskell hasn't seen more adoption is simply because of the current value of shipping fast. However we are in the midst of a Cambrian Explosion of software, and I believe that as the maintenance costs become apparent (as well as parallelization increasing), that the scales will tip towards many functional programming ideas. Maybe it won't be Haskell that sees mainstream adoption, but at the moment it has the most powerful embodiment of these ideas. I wouldn't bet against it based on the parable of Lisp.
Lisp was a language that precisely gained great adoption due to the power it allowed to the individual programmer. The lack of syntax was it's biggest advantage.
Viable ecosystems coalesced around Lisp! Emacs? Lisp Machines? Tons of scientific software? Big AI projects? The whole open source revolution started due to the appeal of the commercial world for Lisp and it's success.
Lisp was a academic and commercial success. The reasons for its decline are multiple, and yet it even was able to come back as Clojure.
And then you have Haskell. A programming language created exclusively by and for the academia. I don't know if you realise that Paul Graham launched his startup using Common Lisp... at a time when Haskell was available as open source too. I'm just using Paul's name as an example of the large community of people who thought (and think) that Lisp languages gave them a productivity and power that couldn't be compared. You even have some commercial video games programmed in Lisp languages! (the famous and repeated example of Naughty Dog). Lisp in finances? Yeap, there are still system using it after many years. Remote probes in deep space? Check. So there must be something to Lisp that helped people to create reusable and maintainable code. And in all these cases it was individual geniouses who pushed for the use of Lisp.
I think that the problem with Haskell is the single promise of its type system. Every single language that boasts to have the silver bullet that will allow people to tame programming (what is nothing more than hard complicated work) has failed to gain adoption by some reason. Diminished returns, maybe. The world is complicated and single techniques that promise to solve everything tend to fall short to the promised benefits. So, how is Haskell going to help me with network protocols? To build better generic software? To interface with the IoT? To create better AI or explore data with Machine Learning? If the answer to these and other questions is "through a hard fully capable type system", then I cannot but laugh.
Then you have languages like R, that are gaining wild adoption in the academia (even if it's a "specific" language) because people feel powerful with them. They can achieve so much more with the same effort that it's a no brainer to use it. Code reuse? Yeah!!!! Thousands of libraries available that work like a charm. Ugly? As hell! but who cares? Oh yes, dogmatic showing-off aestetically/academic inclined posh programmers that represent a small part of the industry, they seem to care a lot (I include myself in this group). And yet smart people is using R every day to the point of forcing people like me (yes I programmed in Haskell in the past) to recognise that there must be something to it. A programming language that transfer a unseen amount of power to the normal user (even if it's an opensource copy of previous software).
As I said, I would like to be able to use the «I reject your reality and substitute my own» card... but after that many years I think that doing so would be just plain naîve.
PD: I would never put maintainability above power (power being defined as "now I can do X easily in half the time"), it seems to never work when it's achieved through "training" and "complexity" (as in for instance "large learning curve").
You're right, I was downplaying Lisp's successes. In fact I wouldn't disagree with most of what you say here, Lisp is definitely more powerful than Haskell.
The part where I disagree is that Lisp holds future promise as a general-purpose language replacement to tame the mess of COBOL / C++ / Java / PHP. I see in Haskell a way to raise the bar for the masses, whether it's Haskell per se or some trickle down effect. Yes, you could build a powerful type system in Lisp, but it is not a widespread goal because it is somewhat conflicting with the raw power argument.
> I would never put maintainability above power
Here is another place I disagree. All else being equal of course I prefer power, but these things are on a continuum. If I can sacrifice a bit of power to greatly increase maintainability or robustness then I believe that is a compromise worth looking at.
I'm curious if you really see no truth in my comment or you really do see programming world in purely blub-theory terms.
Lisp is a language with no syntax, it is like an unshaped lump of clay. It gives you total freedom to implement any computational construct you can imagine. This does allow greater productivity for very small teams, and maybe it's the most powerful tool for the smartest programmer, however it doesn't offer anything to improve the practice of maintenance and reuse. This is why no viable ecosystem ever coalesced around Lisp, and in fact why there are so bloody many Lisps to begin with: because it is attractive primarily to individuals who want to build their own special flower.
Haskell gains its power in an almost opposite way by its type system, it's an extremely rigid structure which contributes tremendously to code reuse and maintainability. It works because great effort was put into the type inference so that it is strong yet lightweight.
IMHO as a seasoned programmer who has spent 5+ years and 7+ years on individual projects, I can definitely see that Haskell is addressing real world problems in a way that Lisp can not. I use ruby day to day, and frankly it's good enough in its meta-programming ability to solve most of the pain that Lisp solves compared to say Java or C++. However when I look at the problems which creep in over a period of years, the code rot, these are things which Haskell trivially prevents while half-hearted type systems like Java don't really put a dent in.
I think the reason Haskell hasn't seen more adoption is simply because of the current value of shipping fast. However we are in the midst of a Cambrian Explosion of software, and I believe that as the maintenance costs become apparent (as well as parallelization increasing), that the scales will tip towards many functional programming ideas. Maybe it won't be Haskell that sees mainstream adoption, but at the moment it has the most powerful embodiment of these ideas. I wouldn't bet against it based on the parable of Lisp.