$\forall$$T$:Type, $L$:($T$ List), $P$:($T$$\rightarrow\mathbb{P}$). ($\forall$$x$$\in$$L$. $P$($x$)) $\Leftarrow\!\Rightarrow$ ($\forall$$i$:\{0..$\parallel$$L$$\parallel^{-}$\}. $P$($L$[$i$]))