Lisp is very under documented compared to other languages. This makes learning LISP extremely difficult.

Let's take a look at HyperSpec, I follow your link and I'm greeted with a mostly blank (and very ugly) page. Ok there is something called starting points, I guess I'll start there. That page just lists all the indexes. Ok let's try chapters, that sounds like a place to start. Oh yay, another page with nothing but links. Ok, let's try introduction. Again, just a mostly empty page with links. Most people would have given up by now. But lets keep going. Let's try 1.1, which takes us to ANOTHER page of links. I'm feel like I'm getting the run around here. Lets click 1.1.1 and see what happens. Finally I get a page that isn't all links, and it's a single paragraph. What a waste of time.

Let's try another language, how about JavaScript? Google gives me this link: https://developer.mozilla.org/en-US/docs/JavaScript Some helpful information on the first page! Do I want a reference? Do I want a guide? Do I want a re-introduction? Maybe some sites with courses on JavaScript! Wow, that's really useful. Lets just start with the guide because it's "Our primary guide about how to program with JavaScript" and that sounds about right. It takes me to a list of links, Yuck, let's try the fist one called "JavaScript Guide" (Isn't that what I clicked on to get here?). Yup, that link just refreshes the page. That sucks, let's try the second link "About this Guide". A page that describes what I should already know, how to find my way around the guide, and tips for diving into JavaScript.

This is the problem with LISP documentation. At best, if I know exactly what I am looking for I find a giant index. At worst I have no idea what I'm looking for and I get snooty comments from LISPers.

The point is you shouldn't make people look really hard to find information. Good documentation should be easy to find and navigate.

The hyperspec is standard document, not an introduction. It's an invaluable reference you use after you get familiar with the language. I also have emacs set up so that I can look up symbols from within my source, and have the relevant page open up in a w3m window in emacs. I use it constantly and miss the same level of quality and clarity in other language documentation, but you need to get used to it's style and format. If you want to get started with lisp, you go to http://www.gigamonkeys.com/book/ and http://www.cliki.net/

Learning lisp wasn't any more difficult for me than learning any other language. "Practical common lisp" is well written. "Object oriented programming in common lisp" is a well written book as well, "Land of lisp" was fun, and not too bad either.

The core language is extremely well documented and understood. As for the libraries, some of them are well documented, some of them aren't. After the docs for RESTAS started going slightly out of date, I just opened the source and read it all in an afternoon(~600loc), and mostly understood it. I prefer not to have to do that, but claiming it makes it extremely difficult to learn, I don't know, to me it's just an inconvenience, and I have a much better understanding of the framework now, which I couldn't get from just reading docs. And some libraries are so small, I can just figure them all by inspecting the package in slime, and reading the docstrings. Usually there is at least example code. The situation isn't perfect, but it is more than possible to use lisp libraries with great success. Most authors are also pretty approachable on irc or the mailing lists. In other words, I'm a young amateur programmer, who picked common lisp less than two years ago, I'm barely competent as a programmer, and I could figure this all out, why can't expert programmers with years of hacking behind them do the same, I can't understand.

PS as for the ugliness of the hyperspec, I'm happy if it scares away people who get impressed by "modern" design, more than substance and content. I usually read it in text only browsers, and curse docs I can't read well from within emacs. Alt-tabbing to a browser and having to use the mouse while hacking ruins my day :)

"I don't think anyone with actual first-hand knowledge of the CL ecosystem would make this comment"

I'll make that statement, but only in a somewhat pedantic sense about the language standard itself. Yes, I know CLTL2 is over a thousand pages long, but the one thing about programming languages that always bothers me is undefined behavior. Sadly, even Common Lisp has undefined behavior; Paul Graham's book On Lisp actually relies on undefined behavior being implemented in a particular way e.g. using setq on an unbound variable.

Good documentation should not leave anything undefined; good documentation should leave no questions about the semantics of a system/API/language. Given source code and documentation, it should be possible (perhaps difficult, but possible) for a person to figure out what will happen if the program is run.

The undefined behavior in the Common Lisp specification was a design choice. It has nothing to do with 'good' or 'bad' documentation. Common Lisp was designed from 1981 on. The Lisp community (here the successors of Maclisp) went to explore a lot of new ground: implementations on mini computers, mainframes, super computers, parallel machines, microprocessors, stack architectures, on top of other programming languages like C, etc. There were small and stupid compilers, optimizing compilers, whole-program compilers, ... It was a time of experimentation. At that time a lot of behavior was not defined to allow compiler writes to explorer different types of implementations. With the knowledge of a decade later some of that could have been defined more precisely, but then the standardization process ran out of steam due to lack of funding and interest.

Using SETQ on an undefined variable may be undefined in the Common Lisp standard, but every implementation deals with that and allows it. That's a non-issue. There are a lot of other things which isn't defined in the standard and which all implementations deal with. Garbage Collection. Also not in the standard, but every user expects garbge to be collected.

It would be nice to have less undefined behavior, but it has nothing to do with good or bad. It was useful in a time of experimenting.

Even worse for Common Lisp was that in 1981 there wasn't yet an OOP system for Lisp that was explored and accepted. This way CLtL1 was defined without an object system and it had later to be added (CLOS).