You can simulate move semantic by using shallowCopy.
proc worker(): seq[int] =
var arr = @[1, 2, 3]
# do some heavy work here
# deep copy is made here
return arr
# or
shallowCopy(result, arr) # move arr to result without copying
return # not necessary at end of function (implicit)
# you can also use result var from the beginning avoid copies.
if you don't like shallowCopy syntax you can use a template to emulate shallow
assignment semantics.
template `:=` (x: var seq[T]; v: seq[T]) =
shallowCopy(x, v)
# used like this
var s0 = @[1,2,3]
let s1 = s0 # no copy is made since s1 cannot be modified
var s2 = s0 # a copy is made here (unless s0 was marked as shallow)
var s3: seq[int]
s3 := s0 # custom template use shallowCopy
there is also the swap proc which swap two variables without any deep copy.
You can laso mess with assignment semantics for types
[https://nim-lang.org/docs/manual.html#type-bound-operations-operator](https://nim-lang.org/docs/manual.html#type-bound-operations-operator)
