Re: When to use formal discrete type?

[Shark8 <onewingedshark@gmail.com>]

On Wednesday, November 29, 2017 at 12:04:35 PM UTC-7, Victor Porton wrote:
> 
> Because it easily generalizes from discrete types to arbitrary private 
> types, should I do generalization?
> 
> What of (generalizing for all private types or not) the two is better:
> 
> a. for clarity of code;
> 
> b. for performance?
> 
> It there a noticeable difference in performance if I generalize?

My rule of thumb is use the most general type as reasonably possible -- so, if you aren't using things like X'First and X'Succ(Value) go ahead and make the parameter private. (On the other hand, if you do find yourself using a value for first/last and/or functions for previous/next consider using more restrictive generic formal parameter; of course, your design might make it impossible to use a discrete-formal [like, say, modeling integrals (for certain models)].)

As for performance, I would recommend that you first benchmark and hotspot-analyze your code: it's typically dumb to spend hours and hours super-optimizing something from O(n**4) to O(n) if n always <= 3. -- Chances are that your intuition as to what's a /real/ performance hit is going to be wrong.