Re: Recursion, Yo

On 12/04/2024 15:03, Janis Papanagnou wrote:

On 12.04.2024 09:30, David Brown wrote:

>
I prefer the consistency of function calls using parenthesis.  The
consistent alternative, found in some other languages, is that they
never need parenthesis - "foo a b" calls "foo" with parameters "a" and "b".

 Mind that this is just one "consistency" aspect.

True.

 Another one is that you can write (e.g. in Algol 68 or many other
higher level languages) the equivalent of - again a simple example -
    int x = 2 * pi * r
 without necessity to know whether pi is a constant, the result of a
function (calculation), the result of a function implicitly called
just once on demand, or whatever else. Conceptually as a programming
language user you want the value.
 

But is that a good thing?  For some programming, especially with higher-level languages, then it is fine.  For other types of programming, you want to know if functions are called in order to have a better idea of the flow of control and the efficiency of the code, plus perhaps thread safety.

I don't say one or the other is "better", just that consistence is
not an absolute property.

Fair enough, and I agree that this is not a matter that has a single correct answer.  It is not uncommon that being consistent in one way necessitates being inconsistent in another way.
Just for fun, this is a way to let you define a function-like object "pi" in C++ that is called automatically, without parentheses :
#include <numbers>
template <auto f>
class Auto_executor {
public :
     using T = decltype(f());
     operator T () {
        return f();
     }
};
static Auto_executor<[](){ return std::numbers::pi; }> pi;
double circumferance(double r) {
     return 2 * pi * r;
}
I am not giving an opinion as to whether or not this is a good idea (and obviously it is completely redundant in the case of a compile-time constant).  Some people might think C++ is great because it lets you use tricks like this, some people might think C++ is terrible because it lets you use tricks like this :-)