Why is the integer named Fixnum in ruby? [closed]

Question

I was wondering why Ruby names it Fixnum; other languages name it Integer, Int, Number, etc. I saw that Fixnum < Integer and Bignum < Integer, and Integer < Numeric and Float < Numeric. I guess it's because of the size:

1.class => Fixnum
(10**100).class => Bignum

And from the doc:

Holds Integer values that can be represented in a native machine word (minus 1 bit). If any operation on a Fixnum exceeds this range, the value is automatically converted to a Bignum

Why the name Fixnum? I thought about fixed number, but it's not fixed, nor fixed size number.

Answer 1

This isn't something Ruby came up with — the term "fixnum" comes from Lisp. Just like in Ruby, a fixnum in Lisp is a number that can be represented by a machine integer. Although I've never seen a primary source to prove I'm right, I've always assumed the "fix" part of the name referred to the fact that it can only represent a fixed range of numbers, in contrast with the limitless bignum (which gets its freedom from limits at the expense of worse performance).