snej, seq is in modern Nim a value object, not a ref. In old Nimrod we could assign nil to a seq, but that is not possible today.
mantielero,
var a:seq[A] = @[B(val:1), B(val:2)]
Run
can not work as Nim is a statically typed language, seq[A] and seq[B] are
different types, so assignment is not allowed.
