Lambda the Ultimate

I was playing around for some time with "functional" thing like Haskell and Erlang. Actually I think things like "Scala" (on JVM) and "F#" (on CLR) are very promising.
But I came across with a new view. I know features like "first class functions" and "concurrency"(in Erlang) are very useful.
Now my question is, in syntax level, is to be declarative as important as to be functional?
(Please include enhancements like multiple assignments and list comprehensions in to be declarative.)

A paper by Charlotte Herzeel, Kris Gybels, Pascal Costanza presented at ILC2007.

Some program concerns cannot be cleanly modularized, and their implementation leads to code that is both hard to understand and maintain. In this paper we consider extending an e-commerce application, written in CLOS, with two of such crosscutting concerns. Though most of the time Common Lisp's macro facilities and CLOS method combinations can be used to modularize crosscuts, we discuss the use of a more declarative solution when crosscuts depend on the execution history. For this purpose we give an overview of HALO, a novel pointcut language based on logic meta programming and temporal logic, which allows one to reason about program execution and (past) program state.

Charlotte Herzeel presented this at ILC with a flashy web-shop application built on Edi Weitz's standard tools of the web trade. The example takes the basic web-shop and uses aspects to add a lot of funky rules about promotion and discounts based on stock levels, what's selling well, what the user has been browsing, etc, and makes sure the discounts are honoured at the checkout.

The focus on adding new and interesting functionality with aspects is refreshing. So is the basis in a powerful language like Lisp. The weakness of most aspect-oriented programming examples in my eyes is that they appear to be working around artificial problems caused by stubbornly using a base language that's ill-suited to the task. That only plays well with the audiences who are also stubbornly using those base languages for ill-suited tasks :-)