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Selecting elements from a given list: `filter'
This abstraction takes a predicate function and a list as its two
arguments. The result returned by `filter' is a new list
containing all elements of the original list, for which the predicate
function returns the value `true'.
![\begin{lstlisting}[language=Scm]{}
(define filter (lambda(p l)
(if (nullp l)
n...
... l))
(cons (car l) (filter p (cdr l)))
(filter p (cdr l))))))
\end{lstlisting}](img132.gif)
![\begin{lstlisting}[language=Scm]{}
(define l1 (cons one
(cons two
(cons thre...
... nil)))))
;
(ldisp! (filter (lambda(x) (gtp x two)) l1))
--> 3
\end{lstlisting}](img133.gif)
Georg P. Loczewski
2004-03-05