Next: Associative Lists in A++
Up: Set Operations
Previous: Adding an element to
Contents
Index
Combining two sets: `union'
This abstraction takes two lists as arguments and creates a new list
having the property of a set by ensuring that elements may not occur more than
once in the resulting list.
![\begin{lstlisting}[language=Scm]{}
(define union (lambda(s1 s2)
(if (nullp s1) ...
...
(union (cdr s1) s2)
(cons (car s1) (union (cdr s1) s2))))))
\end{lstlisting}](img142.gif)
![\begin{lstlisting}[language=Scm]{}
(define l1 (cons one
(cons two
(cons thre...
...! (union l1 l2))
--> 1
2
3
4 ;; kommt nur einmal vor
5
6
\end{lstlisting}](img143.gif)
Georg P. Loczewski
2004-03-05