Scheme is a multi-paradigm programming language. Functional is one such paradigm that it supports. It also supports imperative, object-oriented, relational, a

Scheme is a multi-paradigm programming language. Functional is one such paradigm that it supports. It also supports imperative, object-oriented, relational, and probably others that I don't even know about. In Scheme, one can build functional systems on top of imperative building blocks. For example, memoization can be implemented as a higher-order procedure that uses a mutable hash table as the cache. A memoized function is still pure, despite the use of local state, because it retains the crucial property of referential transparency. Anyway, I guess my point is that the use of 'set!' or 'hash-table-set!' or whatever else doesn't mean that a program is no longer using the functional paradigm. To quote from a Clojure web page[0], "if a pure function mutates some local data in order to produce an immutable return value, is that ok?" [0] http://clojure.org/transients http://clojure.org/transients