$\forall$$A$:Type, $P$:($A$$\rightarrow$prop\{i:l\}), $L$:($A$ List), $x$:$A$.
\\[0ex]l\_all($L$; $A$; $x$.$P$($x$)) $\Rightarrow$ guard((($x$ $\in$ $L$) $\Rightarrow$ ($x$ $\in$ $L$)))