Nonconcrete field types anti-pattern

The nonconcrete field types anti-pattern is an anti-pattern in which a struct field is not concrete. The main problem with nonconcrete types for fields is that they can cause major performance problems. To understand why, let's take a look at the memory layout for composite types that have nonconcrete versus concrete types, then design and compare the two.

Understanding the memory layout of composite data types

Let's first take a look at a simple example for a composite type for tracking the coordinates of a point:

struct Point
    x
    y
end

When the field type is not specified, it is implicitly interpreted as Any, the super type of all types, hence the preceding code is syntactically...