$\forall$$A$:Type, ${\it eq}$:EqDecider($A$), $f$:$a$:$A$ fp$\rightarrow$ Top, $L$:($A$ List).
\\[0ex]l\_disjoint($A$;$f$.1;$L$) $\Leftarrow\!\Rightarrow$ ($\forall$$a$:$A$. ($\uparrow$$a$ $\in$ dom($f$)) $\Rightarrow$ ($\neg$($a$ $\in$ $L$)))