On 04/08/2013 08:14 PM, Simen Kjaeraas wrote:
> Like others have stated, it's so you can do this:
>
> struct Foo {
>    int a = 0;
>    pure int bar( int n ) { // Weakly pure
>        a += n;
>        return a;
>    }
> }
>
> pure int Baz( int n ) { // Strongly pure
>     Foo foo;
>     return foo.bar( n );
> }

... one clear application of this being pseudo-random number generation, where
you have a state variable together with a (pure) update function.