How is the interface in Go structured internally (in memory)?

In Go, an interface is a data structure that contains two main parts:

1. Type — a pointer to the description of a specific type that implements the interface.
2. Data — a pointer to a specific value of that type.

In memory, an interface is represented as a pair of pointers (in the case of an empty interface interface{}) or as a structure with a pointer to a method table and a pointer to data (in the case of named interfaces). This allows dynamic method calls implemented by a specific type.

Here's an approximate representation of an interface:

// Pseudocode of the internal representation of an interface
struct iface {
    tab  *itab  // method table and type
    data unsafe.Pointer // pointer to data
}

The itab table contains information about the type and pointers to methods, which allows determining which specific method of a type to call when an interface method is invoked.

Thus, an interface in Go is a mechanism of dynamic dispatch implemented through a pair of pointers, providing flexibility and type safety at runtime.