It depends on how broadly you define 'functional'. Back in the day just having closures and anonymous functions was probably enough to qualify. But nowadays Jav

It depends on how broadly you define 'functional'. Back in the day just having closures and anonymous functions was probably enough to qualify. But nowadays Javascript and any other number of scripting languages have those features too. I can't think of any respect in which Common Lisp encourages or requires a functional style to a greater extent than, say, Javascript. It's also worth mentioning that the Common Lisp standard does not require implementations to implement tail call elimination. The pervasive use of a functional style in CL would therefore give rise to programs with performance characteristics that could, at least in principle, vary greatly between implementations. (I'm aware that most popular CL implementations do optimize away tail calls in practice.)