* Damien Bobillot:

>> The C language interface falls into this category.  Are there any
>> other problematic areas?
>
> The Obj.magic function. I don't know exactly what it does, but I  
> think it does arbitrary type conversions.

Apparently, it creates a bit-wise copy of a value and assigns it a new
type.

I discovered that there are also a couple of undocumented unsafe_*
functions, such as String.unsafe_set, which behave the way their names
imply (no bound schecks).