Class default

A CASC float (CASC.md §6.3), as a consumer's own tag receives one.

CASC tells 2.0 from 2, and so does the reference: its tags are handed an Elixir float, which is_integer/1 refuses. A JS number cannot carry that difference, so inside a load every float is a CooperFloat -- which is what lets "@{f}" read 1.0, -key = [1.0] leave 1 alone, and !int(2.0) fail. A tag registered with tags: is handed the argument exactly as the pipeline holds it, so a float reaches it wrapped, nested ones included (in a list, a tuple, a map, or a secret); an integer is a plain number (or a bigint). A tag may return a CooperFloat too, and the value stays a float for the rest of the load. Once a tag handed its argument plain numbers, and could not tell !twice(2.0) from !twice(2).

The loaded tree never holds one: every float in the result is a plain number, the host's single number type.

value, toNumber() and valueOf() give the number, so arithmetic (f * 2) works on it as it is; toString() writes it as CASC does, always with a fraction (2.0, 1.0e3, inf). Infinity is never wrapped by the pipeline -- inf has no integer twin to be told apart from -- but a consumer may wrap it.