Thinking about the difference between fixed and 'dynamic' arrays.

[Paul Backus]

On Tuesday, 29 November 2022 at 18:59:46 UTC, DLearner wrote:
> To me, it appears that there are really two (_entirely 
> separate_) concepts:
>
> A. Supporting the useful concept of variable length (but 
> otherwise entirely conventional) arrays;
> B. Supporting a language feature that acts as a window to an 
> array, through which that array can be manipulated.
>
> And currently these two concepts are combined.

Yes, this is correct.

> Suggestion: it would be clearer if the two concepts were 
> separated:
> 1. Convert 'int[] VarArr;' so it produces a straightforward 
> _value-type_ variable array, called 'VarArr';
> 2. Implement a new concept 'int slice Window;' to produce an 
> object of type 'int slice', called 'Window'.
>    'Window' is a 'slice' into an int array, not an array itself 
> or even a variable.
>
> Opinions?

IMO you have it the wrong way around. The built in `T[]` type 
should remain the way it is and be used if you want a slice 
(i.e., a "window"). If you want a dynamic array with value 
semantics, you should use a library-defined container type (e.g., 
`struct DynamicArray`).

Also, to avoid confusion, we should probably go through the 
language spec and documentation and change it to say "slice" 
instead of "dynamic array" whenever it refers to a `T[]`.