$\forall$$T_{1}$, $T_{2}$:Type, $f$:($T_{1}$$\rightarrow$$T_{2}$), $Q$:($T_{2}$$\rightarrow\mathbb{B}$), $L$:$T_{1}$ List.
\\[0ex]filter($Q$;map($f$;$L$)) $=$ map($f$;filter($Q$$\,\circ\,$$f$;$L$)) $\in$ $T_{2}$ List