How about 'pure' for constants?

[Sean Kelly]

Don Clugston wrote:
> IIRC, there was a suggestion at the conference that D would get a new 
> reserved word, 'pure', for functional programming. This should be 
> considered as an alternative to 'enum'. I really don't like the idea of
> 
> enum SomeEnormousStruct a = SomeFunction(AnotherEnormousStruct(x, "abc"));
> 
> (and my CTFE code is already full of this sort of thing. It's simply not 
> true that 'enums' would mostly be integral types).
> 
> Seems to fit with the idea of 'having no side-effects' - a pure value 
> would not be stored anywhere, and make no contribution to the size of 
> the executable.
> 
> pure real pi = 3.141592564;
> 
> // this is really silly if you use 'enum' instead.
> pure real myNaN = real.nan;
> 
> BTW, a pure function taking only pure parameters returns a pure value, 
> so this seems to be entirely consistent:
> 
> pure int foo(int a, int b);

I've been wondering the same thing, but couldn't decide if the keyword 
made sense in this context.  But by your explanation it clearly does. 
It has my vote.


Sean