An apt definition of functional programming

While reading Jukka Paakki's paper on attribute grammars I found out that it contains a pretty apt definition of functional programming that I have been learning over the past year. So here it is for the public's delight (OCR'd, so the possible typos might not be original):

"The functional style of programming can
be summarized with the following characteristics:

• referential transparency
• higher-order functions
• lazy evaluation
• pattern matching

Referential transparency is the term used
traditionally to express that the value of
an expression depends only on the values
of its subexpressions, and that the value
of each occurrence of an object is the
same, irrespective of the context. In other
words, side effects are ruled out. Functions
being higher-order means that they are
first-class values and can, for instance,
be stored in data structures and
returned as result of function calls. Lazy
evaluation is tantamount to "nonstrictness,"
meaning that the value of an object is not
computed until it is actually needed, and
thus the value of an argument may be
undefined when calling and executing the
function. Pattern matching is a general
term used to express the mechanism applied
when trying to make X and Y identical in an
equation X = Y where X and Y are expressions.
Pattern matching is restricted in functional
programming to introduce bindings only to
the left-hand side X when solving such an
equation."
(Paakki, J. 1995. Attribute grammar paradigms—a high-level methodology in language implementation. ACM Comput. Surv. 27, 2 (Jun. 1995), page 236.)

What could be added is the concept of recursion.