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Selector `car'
The abstraction `car' selects the head of a pair:
![\begin{lstlisting}[language=Scm]{}
(define car (lambda (l)
(l true)))
\end{lstlisting}](img91.gif)
`car' is equivalent to a function that is passed a list as an
argument![[*]](../img/footnote.gif)
.
The list is invoked as a function with `true' supplied as an
argument. `true' by definition is a selector returning the first
of two arguments, which in our case is the head of the pair or list.
Georg P. Loczewski
2004-03-05