I have no idea what shallowCopy(list.v, s) should do in this case.
Your v : seq[int] and your let s = @[1, 2, 3, 4, 5] both defines value types.
Well v is a field of a reference to an object, but v is still seq, and seq are
value types in Nim, when v get filled with data v allocates its own data buffer
and stores its values there. I would guess what you want is v : ref seq[int].
Maybe with
#let s = @[1, 2, 3, 4, 5]
var s = ref seq[int]
s[].add(1) # or s[] = @[1, 2, 3, 4, 5]
list.v = s
Run
