According to Wikipedia Functional Programming fits under the Declarative Programming paradigm. I'm not sure how accurate that is, but it seems to hold some truth.

"Functional programming, and in particular purely functional programming, attempts to minimize or eliminate side effects, and is therefore considered declarative."

"While functional languages typically do appear to specify "how", a compiler for a purely functional programming language is free to extensively rewrite the operational behavior of a function, so long as the same result is returned for the same inputs."