[gambit-list] Promises & lazy thunks

Marc Feeley feeley at iro.umontreal.ca
Tue Apr 30 10:46:48 EDT 2013


On 2013-04-29, at 5:12 PM, Bradley Lucier <lucier at math.purdue.edu> wrote:

> 
> On Apr 29, 2013, at 4:31 PM, Jason Felice wrote:
> 
>> 
>> On Mon, Apr 29, 2013 at 4:13 PM, Marc Feeley <feeley at iro.umontreal.ca> wrote:
>> 
>> Primitives like "cons" and "list" should not force their arguments because they are not strict (i.e. they don't need to know the value of the arguments).
>> 
>> It isn't clear if type predicates are strict or not.  I can see arguments both ways.
>> 
>> Hmm, I can't think of a reason to make them lazy.  What's the thought?
> 
> Well, if you'd like to see whether something is a promise or a fixnum, you'd have to call (promise? x) first if (fixnum? x) always forces its argument.
> 
> I've been thinking about this a bit, I'm not going to use the auto-force Gambit, but perhaps the type predicates should be made consistent.

I agree with the consistency argument.  So now fixnum? and flonum? auto force their argument like all other type predicates (except ##promise?).  Please let me know if you find other cases.

Marc




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