\begin{tabbing}
ecl{-}m3($a$;${\it snd}$;$x$;$l$)($k$)
\\[0ex]$\,\equiv$$_{\mbox{\scriptsize def}}$$\;\;$\=let $g$ = ${\it snd}$($\langle$$k$$,\,$$l$$\rangle$)?nil in \+
\\[0ex]map\=($\lambda$${\it tr}$.let ${\it tg}$,$n$,$f$ = ${\it tr}$ in $\langle$${\it tg}$$,\,$$\lambda$$s$,$v$. if $a$($n$,$k$,$s$,$v$,$s$($x$))$\rightarrow$ $f$($s$,$v$) else nil fi$\rangle$\+
\\[0ex];${\it snd}$($\langle$$k$$,\,$$l$$\rangle$)?nil)
\-\-
\end{tabbing}