Edit the document below; results appear inline as you type. The document is self-contained: it imports the stdlib it needs, so it evaluates even against an empty knowledge base.
import nelumbo.integers
Integer ::= fib(<Integer>)
Integer n, f
fib(n)=f <=> f=n if n<=1, f=fib(n-1)+fib(n-2) if n>1
Integer r
fib(7)=r ?