On 01/04/2011, at 10:12 PM, Rhythmic Fistman wrote:
> I was binding some c code and needed to use null pointer.
> Obviously 0 didn't work (it's an int, not a pointer!) but then I
> remembered c_hack
> and null[T] and did this:
>
> proc do_something: &long_type_name = "c_do_something($1);";
>
> var x : long_type_name;
> do_something(&x);
> /* ... */
> do_something(null[long_type_name]);
>
> Do I really have to type null[long_type_name]? Why can't I just type null?
Because you do :)
Felix can only deduce types bottom up.
So to overload the function do_something the argument
type must be known, so you have to specify it.
Unlike C++ where there are automatic conversions.
To put this another way, Felix doesn't support polymorphic
constants. This is particularly annoying in typeclasses
where you'd want
typeclass Integer[T] {
virtual const zero: T;
axiom add ( x:T, zero ) = x;
}
but if you look in the library we actually have
virtual fun zero : 1 -> T;
instead ;(
--
john skaller
[email protected]
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