In a previous article, I wrote about how it was difficult to produce a 2D list in Copper due to the ownership dilemma. The solution at the time was to write a singly-linked list in Copper. It turns out, there is a better approach, one that will also allow us to create any multi-dimensional list.
Suppose you wanted to create a 2-dimensional list. This can be easily done with the list constructor. ex:
mylist = list(list(9))
Now suppose we wanted to access the item in the second dimension of the list. Lists are special in that they are objects that contain other objects without themselves containing variables. To access an item in the list, we use the item_at() system function. This returns an object. Performing it once will return the child list. From there, we can call item_at() in succession to access the item of interest:
myitem = item_at(item_at(mylist: 0) 0)
Under the hood, Copper is a rather complicated system. It has to be that way in order to ensure Copper is safe (no null pointer errors) within Copper code. However, on the C++ side, this makes it tricky to just access the members and data of a FunctionObject, the most important of all Copper objects. Now there’s an easy way.