Purity (D2 standard libraries / object.d)

[Walter Bright]

Michel Fortin wrote:
> Hum, could the compiler be trusted to add the memoization code to pure 
> functions so they can stay pure?

If the compiler does general memoization on pure functions, all it has 
to do is use the bits of the arguments passed on the stack to the 
function as an index into an associative array of the return values.

The problem is identifying if this would be faster than recomputing the 
return value.