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

[Stephen J. Turnbull]

Chris Angelico writes:

 > That effect, yes. Let's call it "the magic of float.__str__", because
 > it really is pretty amazing.
 > 
 > But it's still post-processing magic. It means that strings appear to
 > round-trip through floats, as long as you're a long way within the
 > available precision; but as soon as you do operations, that ceases to
 > be the case. I think it's great for display, but is putting that into
 > __repr__ (at least, they do appear to be the same) an attractive
 > nuisance, in that it encourages people to treat float("...") as a true
 > representation?

What makes you think they need more encouragment?

Seriously, as one data point, I don't think having more "human"
representations encourages me the think of floating point results as
the product of arithmetic on real numbers.  I don't think anybody who
knows how tricky "floating point" arithmetic can be is going to be
fooled by the "pretty eyes" of a number represented as "2.0" rather
than "1.99999999999999743591".