english: We like our structures to be defined in terms of a single well-formed type, so if we had an arbitrary type \(A\) and a type of lists \(L\) defined in terms of \(A\), i.e. \(L\;A\), it would be inherently impossible to construct nested lists, due to it leading to the (impossible) equality \(A = L\;A\).
non_english: これで、ナイトさんを、混乱させる！ナイトさんのテスト、✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✗✗✗✗✗✗✗✗✗✗✗✗✗✗✗✗✗✗✗