[Python-ideas] Python Numbers as Human Concept Decimal System

[Andrew Barnert]

From: Steven D'Aprano <steve at pearwood.info>

Sent: Friday, March 7, 2014 10:08 PM


> On Fri, Mar 07, 2014 at 09:40:47PM -0800, Mark H. Harris wrote:
> 
>>  hi Andrew, I have been studying the python-ideas archive & the 
>>  python-dev archive all night. I have read hundreds of posts. I am 
>>  finding something very interesting. My proposal has been coming up 
>>  (time and again) in different flavors for many years; with all the 
>>  same people participating (with all of the very same discussion almost 
>>  verbatim).
> 
> Which proposal? You have made a few, and I cannot keep track of which 
> ones you still stand by and which ones you have abandoned.

I agree that some clarity would be nice here, but I think from the quote he quoted it's pretty clear that he's talking about the decimal-literal proposal, not any of the ones that you mentioned.

> - that Python unify all numeric types to one "Python 

> Number" (I think this is abandoned)
> 
> - that Decimal(float) use AI to determine what number the programmer 
> wanted (you've agreed to stop using the term "AI", but I'm not 
> entirely 
> sure whether you've moved away from this position entirely -- you 
> still describe Python as needing to "intelligently" convert floats)


I'm still not sure exactly what Mark's proposal is here, but Guido has developed this one into something concrete and feasible: change the default conversion from float to Decimal (that is, Decimal(float)) to use the repr. I don't want to put works in Mark's mouth and say that's what he's interested in here, but I can say that it looks like it would solve the problem cases Mark has brought up.

> - that allowing Decimal(float) at all is a mistake and should be 
> prohibited
> 
> - that the default numeric type when the programmer enters a numeral 
> with a decimal point like 2.01 be Decimal