playing with array references in Nim

makeRefArray.nim

func makeRefArray[I,T](initArray: array[I,T]): ref array[I,T] =
  var refArr: ref array[I, T]
  new(refArr)
  refArr[] = initArray
  refArr

# We can't assign to a normal let-array
# let myArr = [1,2,1]
# myArr[1] = 5


# But we can assign to a refArray
let myRArr = makeRefArray([1,2,1])
myRArr[][1] = 5
echo myRArr[]

# Unfortunately we can also do this
myRArr[] = [3,3,3]
echo myRArr[]


## Try 2 (with ref object)

type RefArray[I,T] = ref object
  arr:  array[I,T]

func `[]`[I,T] (rArr: RefArray[I,T], ix: I): T = rArr.arr[ix]
func `[]=`[I,T] (rArr: RefArray[I,T], ix: I, val: T) =
  rArr.arr[ix] = val

func makeORefArray[I,T](initArray: array[I,T]): RefArray[I,T] =
  let refArr = RefArray[I, T](arr: initArray)
  refArr

let myORArr = makeORefArray([1,2,1])
myORArr[1] = 5
echo myORArr.arr

# Unfortunately we can also do this (though only in the module, I think)
myORArr.arr = [3,3,3]
echo myORArr.arr