The core types use doubles, not floats.  The file and function names
should reflect that (the docs already do).

'float' is how python names its floating point number type, and this
won't change.  Yes, it is based on the C double, but I think that the
code is very careful to avoid the confusion.

For example, in the C sources, the word 'float' always has a 'Py'
prefix, or an 'object' suffix, to assert that it refers to the python
type (e.g. PyFloat_FromDouble, floatobject.c)

Do you have a precise example where the distinction is not clear?

-1

The time to change this was 3.0, if it was ever needed. It would break
too much code now. We could develop some strategy using macros, but I
just don't think it's worth it.

And as Amaury points it, the type is known in python as "float", so to
change it would be confusing. That it uses C doubles is an
implementation detail.

As Amaury explains, it's called float because it *is* a floating point
type. 

It is not a double type, as it is not two types, but only a single one
:-) In 2.x, the "int" type was also represented with a C long, yet the
type called "long" was not represented with longs but with shorts.