I started seriously focusing on learning Lisp perhaps a year ago. My exposure to Perl had brought me to the point where I understood the idea of functions as first class in their own right.
Lisp rolled forward my mind into new places of understanding how to program. It was like having lights flicked on all over the place. I've been able to conceptualize post-Lisp in ways I did not before.
Perhaps Haskell would have done similar things. I can't say. But Lisp definitely did, and I believe that given the project (and a sufficient lack of having to interface into weird libraries), I could do more in a given slot of time in Lisp than I could with other languages.
Yeah, Lisp is a really good mind-bender. If you picked up some good experience with CLOS, I recommend using the Moose packages in your perl work. Moose adds to Lisp's default CLOS with lazy attributes, roles, and a functioning type system.
SML, OCaml, and/or Haskell will show you a new way of looking at types (and secondarily, expose you to unification on a level that is a little deeper than destructuring-bind). If your background is in perl and then some Lisp experimentation, I recommend checking these others out in order to fill in this other nice piece in the equation. Finally, once you have convinced yourself that type systems are the hotness, it will be good to expose yourself to Erlang, specifically with regard to error handling and the role of supervisors for process restarts.
Lisp rolled forward my mind into new places of understanding how to program. It was like having lights flicked on all over the place. I've been able to conceptualize post-Lisp in ways I did not before.
Perhaps Haskell would have done similar things. I can't say. But Lisp definitely did, and I believe that given the project (and a sufficient lack of having to interface into weird libraries), I could do more in a given slot of time in Lisp than I could with other languages.