What purpose to const besides functional programming?

[superdan]

Walter Bright Wrote:

> Jason House wrote:
> > Walter Bright Wrote:
> >> It is one of the points of the const system. But the idea is not to
> >> just declare things invariant and magically they will work in
> >> functional style. The idea is that if you want to make something
> >> functional, the language will provide support for it if only in the
> >> form of telling you when something will not work in functional
> >> style. That appears to be the case with bar() - it cannot work in
> >> functional style.
> > 
> > Can you answer this more thoroughly?  It's really important to this
> > dialog.  What *other* purposes does the const system serve besides
> > opening the door to functional programming?  I understand that the
> > const system must remain simple to be usable.
> 
> 1. It makes function APIs self-documenting.
> 2. Invariance allows one to pass large data structures around by 
> reference yet treat them as if one passed them by value. Strings are the 
> canonical example of that.
> 3. Const allows one function to service both mutable and invariant 
> arguments.
> 4. Invariant data can be placed in hardware protected readonly memory, 
> such as ROM.
> 5. Invariant data does not have to be synchronized to be multithread 
> accessible.
> 6. Invariant data improves the ability of automated tools to make 
> inferences about what is happening. Optimization is an example of such.

yeah. tell brad or andrei or whoever came up with that stuff that i'll buy them a beer for point 2, i'll wash their feet for 3, and i'll buy them dinner at ritz for 5. fuckin' a.