$\forall$$T$:Type, $L$:$T$ List, $P$:($T$$\rightarrow$Prop). ($\forall$$x$$\in$$L$. $P$($x$)) $\Leftrightarrow$ ($\forall$$i$:$\mathbb{N}$$_{\mbox{\scriptsize $<\parallel$$L$$\parallel$}}$. $P$($L$[$i$]))