from index.d.ts:

export interface SArray<T> {... }
export interface SDataArray<T> extends SArray<T>

I would proffered this be written as:

export interface SArray<T> extends ReadonlyArray<T> { 
   // only S-Array specific function mentioned here
}
export interface SDataArray<T> extends SArray<T>, Array<T> { 
   // only S-Array specific function mentioned here
}

Obviously the implication are

1. The additional function and their overloads presented in Readonly/Array would need to be implemented in S-Array.
2. Existing functions with different signatures would need to be changed or overloads added
   • I experienced this issues with .map function, when used with more than 1 argument.

The reason is this would allow general (generic) function to be written that can handled both types. Also converting code to-and-from standard array / s-array.

What is your opinion?

Thank you.