[Grace-core] Top type?

[Kim Bruce]

So the hierarchy is:

Done
    |
Object
   |
other object types
   |
None

Thanks!

Kim



On Jul 9, 2013, at 11:03 AM, James Noble <kjx at ecs.vuw.ac.nz> wrote:

>> The spec says that Object is the top type.  Is that correct, or is it Top.  None is the bottom type, yes?
> 
> I *remember* talking about this at Claremont with you * Andrew, the same time variables went lexical.
> 
>> Minutes of Teleconference 2012.01.04-05
> 
> says
>> Any - top type, type of any object
>> Object - type of most objects
>> Void - return type of Commands
>> None - bottom type 
> 
> 
> But Mintues from Meeting 2-3.07.2012 includes Andrew's notes which says
> 
> 
> <Grace meeting 2 July 2012.rtf>
> 
>> object {}   inherits from graceObject, which is of type Object.
>> 
>> graceObject has methods for comparison, its corresponding hash, asDebugString, and asString.  It inherits from done. 
>> 
>> done is an object that has no methods other than asDebugString.  Its type is called Done.  The value done is returned 
>> from methods that have nothing better to return.   All other types conform to Done.
>> 
>> None is the type with all possible methods.  It is uninhabited.  None conforms to all other types.
>> 
>>