This paper describes the situation in the mid-1980s as a "lazy Tower of Babel" with competing lazy-functional languages like Miranda, MLs, Orwell, Clean, Ponder, each good in its own way, but none of them with critical mass. Thus they decided to create Haskell as a new, common language. No doubt each language designer felt that Haskell compromised on their particular vision, but rallied around it anyways, resulting in a far more potent force for lazy functional programming than ever could have been achieved working separately.

Why does this not describe LISP today? Honest question.

Back in the 70s and 80s there are numerous Lisp dialects (way, _way_ more then there are today, since each dialects has their own sub-dialect and so forth), and so Common Lisp was created back in the 80s (the work started in 1981 and finished in 1994) to unified various Lisp dialects into one common language.

And Common Lisp accomplishes that objective, well mostly anyway. Soon(-ish) most people, companies, and institutions ported their Lisp code base to Common Lisp, and by the late 80's and early 90's, when you say Lisp most people will (correctly) assume that you mean Common Lisp, not MacLisp or InterLisp, or some earlier, long depreciated dialects.

You can read more about the nitty gritty details in the Evolution of Lisp essay by Richard Gabriel here: http://www.dreamsongs.com/Essays.html

Now, about Scheme. Remember when I said that Common Lisp _mostly_ accomplishes its objective of unifying various Lisp dialects? Yeah, basically the Scheme community didn't like how Common Lisp turns out, so they decided to stick with Scheme. And it is understandable why they feel this way, because despite outward appearance, the two languages are very different, with Scheme focuses on small (and mathematically elegant) core language, while Common Lisp, with its focus on being practical, is a huge language with a standard library that includes everything and a kitchen sink. Scheme also has a totally different evaluation model compared to Common Lisp and its own macro system with emphasis on hygienic. Not to mention that Scheme has its own standard, the R*RS (now in its 6th revision, with 7th in the drafting process).

Now, the thing about Common Lisp is that it is very hard, if not downright impossible, to change its standard. This means that it is not easy to make a substantial changes to the language and has the wider community adopt it (and we haven't even talk about changes that will break backward compatibility here). This is one of the reason that Rich Hickey created Clojure as an entirely new Lisp dialect (before this, he had implemented a Java FFI for Common Lisp). Clojure has a new syntax that is far more consistent than Common Lisp (which comes at the cost of breaking backward compatibility), as well as many new and experimental features, such as immutability, asynchronous operations, and the focus on functional programming style. All of these would be very hard to introduce into Common Lisp without significant efforts and time.

I don't think it's really fair to say modern Schemes aren't focused on being practical. Nor that they're small.

Take a look at Chicken or Racket, and you'll see that they have quite substantial libraries and many features above and beyond the specs that make them much more practical than the core Scheme spec alone.

Quite beside that, there's also the new R7RS[1] spec's "large" language is just that: large. It's also focused on being practical. So I wouldn't say that the traditional Scheme vs CL divisions in terms of size and practicality still hold.

I would say that Scheme is more elegant than CL, and more modern, and less crufty. Unfortunately, there are still far more programmers using CL than Scheme. Hopefully with Emacs' move to Guile that will change.

That said, I still love CL, and would far rather use it than any other language, except Scheme.

[1] - http://trac.sacrideo.us/wg/raw-attachment/wiki/WikiStart/r7r...

Scheme is another language with its own common standards.

The way people are so quick to talk about "Lisp" as a general meta-language is kind of confusing.

We could invent a definition by which Ruby, Python, and Perl are "really the same language" that just failed to standardize, but that would be obviously silly.

Whereas LISP-like languages have data structures that are generally immutable, and whose functional orientation results in expressing the computation of new data from old (mostly) without mutating in-place.

The thing about imperative programming languages is that the paradigm matches up to the mental model of "a computer" that most programmers would recognize and find comfortable. Without having any concrete evidence, I have a hunch that this paradigm difference is what deters new developers the most. And stacked on top of that you have the non-ALGOL syntax and the lack of libraries.

In my opinion, anyway.

I'm curious about where the idea originated that Lisp is an especially non-mutating language. Some of it is just that it's a garbage collected language with first class functions, so it's easy to classify it as "functional" which has associations to "pure functional." But Lisp is very far from a pure functional language. It's more like a general multi-paradigm language—like Perl and Ruby.

The paper I linked discusses some of the "practical" areas of Haskell: profiling, debugging, packaging, FFI, compiler errors and optimizations, etc. Surely there's a lot of energy being expended replicating this stuff across the various Lisp implementations?

Common Lisp has unified packaging and FFI and stuff through various community projects like ASDF and Quicklisp.

If you're talking about Lisp in the general vague sense of "Lisps" then there can't be general interoperability because that umbrella term covers lots of very different languages with no formal common ground.

For Common Lisp, the open source ones are SBCL and Clozure CL, and the proprietary ones are Allegro CL and LispWorks.

For Scheme, there are Racket (PLT Scheme), Chicken Scheme, and Guile.

I'm quite certain that the majority of people who use Common Lisp and/or Scheme use one of the aforementioned implementations.