"In the case of AOLserver [...] Jim Davidson and Doug McKee had only a few months to build the whole server from scratch. They wanted users to be able to write small programs that ran inside the server process. They therefore needed a safe interpreted language so that a programming error by one user didn't crash the server and bring down all the Web services for an organization.
Tcl was available. Tcl was easy to download and designed to fit inside larger application programs. Doug and Jim [could] read through the Tcl source code and modify it to be thread safe. So it was critically important for them that Tcl was open-source and simple enough so as to not require months or years of study to understand the whole system.
Compare this to Lisp. Some of the best and brightest computer scientists raised money to build commercial Lisp implementations that they then went out and hawked in an indifferent and confused marketplace. They succeeded only in breaking their hearts and their investors' wallets. A handful of academics produced free open-source implementations, notably CMU Common Lisp and various versions of Scheme. But these multi-megabyte monsters weren't designed to fit neatly into someone else's program. Nor was there any document explaining how to do it.
Lisp developers have the satisfaction of knowing that they got it right 30 years before anyone else. But that's about all they have to show for 40 years of hard work and hundreds of millions of dollars in government and private funding. These days, most former Lisp programmers are stuck using Unix and Microsoft programming environments and, not only do they have to put up with these inferior environments, but they're saddled with the mournful knowledge that these environments are inferior."
— Phil Greenspun in TCL for Web Nerds
Something or someone pointed me to this quote a few months ago, and I forgot about it, but it came back to my head recently in the context of some or other discussion. Probably about the Sisyphean struggle I had in using Guile as a scripting language.
I keep coming back to Guile because I think that they, of everyone, may actually have a chance at building a stable, usable Scheme interpreter. Maybe Lisp (shut up, Scheme is Lisp, especially to a C hax0r like me) isn't so dead. But the important point to take away from this is that in the real world—sorry, that's a little harsh—outside of academic contexts, what determines the success of a particular programming language is everything except the actual programming aspect of it.