[em7]

UML is not only about class diagrams.

If you use classes and objects in LISPs (Common Lisp, Scheme, Clojure...), you can create the class diagrams and they will work. In Clojure I usually started (and I've seen others do the same) with some functions which operates over hash-maps (or a-lists in LISP). And on the end of the day, when I was creating the interface for call from java, I put the the needed hash-maps to defrecords. If I did the class diagrams, it was afterwards when the relationship between records was clear. Honestly, I don't usually create them anyway even at my work (C#) - only when the releationships between objects are complex or in some "unexpected" ways.

But other UML diagrams are perfecly applicable even in functional languages. The component diagram, use case diagram, communication diagram ... they are universal. The same for E-R diagram - if you use relational database in functional/logical language, it's sometimes good to have it.