Re: Dynamic Typing Efficiency

>The problem I have is that dynamic typing seems to be extremely
>inefficient when you have a large number of types. For example, if I


  Why is this so inefficient?


>have integers, doubles, strings, booleans, and various compound types,
>then an ADD instruction would have to look like this:


>...
> else if (operand1->type == INTEGER && operand2->type == DOUBLE)
> {
> value.d = (double)operand1->val.i + operand2->val.d;
> type = DOUBLE;
> }




Your example just shows that you choose the wider of the two operand types
and widen the narrower That ought to be straightforward, if you define a
"width" for each numeric type.


Once you add user types things can get more complicated. If you use C++
style single-dispatch you have one dispatch for the object type (in C++
this is simply an indirection) followed by another method lookup for the
argument type.


I have no idea how Dylan implements multiple-dispatch. SOme sort of
runtime mattern-matching?


--
mac the naïf

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