I learned C and LISP pretty much at the same time (back when rocks were young and you needed a PDP-11 if you wanted to run Unix). Then I went to college and the

I learned C and LISP pretty much at the same time (back when rocks were young and you needed a PDP-11 if you wanted to run Unix). Then I went to college and the first course in the Computer Science major was a "killer" they taught in Pascal. Okay, so Pascal is a kind of screwed-up C, and I could deal with that. That "killer" course had a semester-long, multi-phase project that was a kind of symbolic calculator (with sets and operations on them). It was maybe a couple hundred lines of LISP . . . so I wrote a LISP interpreter in Pascal (with a garbage collector, natch), then wrote the meat of the project in LISP, embedded in the Pascal source. Was the only person in a class of 300 or so who completed the project that semester, but the professors were not amused with the approach I took. Can't imagine why :-) I've never used a functional language in production, but I've stolen LISP techniques and used them in quite a few products. I never felt frustrated by the fact that I couldn't use LISP or Scheme or whatever in <product> and had to use C/C++/Pascal/Java/C# instead, but have seen it happen in other engineers (notably when the Apple Newton switched from Dylan -- an object-oriented variant of Scheme -- to C++; there were a bunch of forlorn looking ex-Scheme hackers wandering the hallways, clutching copies of the C++ Annotated Reference Manual and trying not to cry).