Type erasure

Wikipedia defines type erasure as the following:

the load-time process by which explicit type annotations are removed from a program before it is executed at run-time

In other words, let us pretend there are two variables defined per the following pseudo-code:

var ints = List<Int32>{1, 2, 3}
var strs = List<String>{"Hello", "world"}

The above pseudo-code makes it perfectly clear that ints is a list of 32-bit integers and strs is a list of string values. Languages that practice type erasure would transform the above pseudo-code to looking something a litle more like this at runtime:

var ints = List{1, 2, 3}
var strs = List{"Hello", "world"}

At runtime there is nothing to distinguish the type of ints from strs without looking at the types of the elements in those lists. This is a very common example of type erasure, one which is present in a very popular programming language. Let’s see just what impact that has by continuing to the next page…

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