Any way to work around that capturing closures cannot be materialized as runtime values?

@value
struct Column[T: CollectionElement]:
    var getter: fn (v: Vector, length: Int, offset: Int) capturing -> List[T]

    fn __init__[ChildType: CollectionElement](inout self: Column[List[ChildType]], child: Column[ChildType]):
        """Initialize a list column from a child column."""

        fn list_getter(v: Vector, length: Int, offset: Int) capturing -> List[List[ChildType]]:
            var l = List[List[ChildType]](capacity=length)
            for idx in range(length):
                l.append(child.get(v, length, offset + idx))
            return l
        self.getter = list_getter
    # ...
    fn get(self, v: Vector, length: Int, offset: Int) -> List[T]:
        return self.getter(v, length, offset)

TODO: capturing closures cannot be materialized as runtime values