I would say the easiest to learn is Common Lisp because of the amazing debugger + conditions/restarts. If you make a mistake, instead of aborting the program li

I would say the easiest to learn is Common Lisp because of the amazing debugger + conditions/restarts. If you make a mistake, instead of aborting the program like most programming languages would, Common Lisp will give you a list of restarts which let you specify how to continue executing (change variable values, return a new value instead, etc). To learn it I would recommend COMMON LISP: A Gentle Introduction to Symbolic Computation to get a good foundation. After reading that, I would suggest ANSI Common Lisp, which introduces some of the more advanced features and gives some pretty good examples of what you can do with Lisp (writing a DSL for generating HTML is one of them). Then I would recommend On Lisp which gives all kinds of crazy things you can do with Lisp (embedded Prolog, DSL for parsing English, and many other cool things). There are many other great books out there which you may way want to look at. Land of Lisp and Practical Common Lisp are both good introductory books, but I find that they introduce too much too fast and it makes it difficult to get very far in them. Paradigms of AI Programming is probably one of the best programming books out there, but there is a lot of advanced material in it.