Numbers

There are two kinds of numbers, integer and float (floating-point number), both are represented with 29 bits value and 1 bit sign. Thus, integers range from -536,870,912 to 536,870,911. Floats can represent plus/minus from 4.8E-38 to 3.8E38 with the approximate accuracy of 6 digits in decimal, i.e., floating-point epsilon is approximately 1/1,000,000.

Numbers are always represented by immediate data, and not by objects. This is the only exception of EusLisp's object orientation. However, since numbers never waste heap memory, number crunching applications run efficiently without causing garbage collection.

EusLisp does not have the character type, and characters are represented by integers. In order to write a program independent of character code sets, #\ reader dispatch macro is used. However, when the character is read, it is converted to numerical representation, and the printer does not know how to reconvert it to #\ notation.

A number has two tag bits in a long word Figure 2, which must be stripped off by shifting or masking when used in arithmetic computation. Note that an integer should ignore two MSB bits by arithmetic shifting, while a float should ignore two LSB bits by masking. Byte swap is also necessary for an architecture like VAX which does not use the rightmost byte as the least-significant mantissa byte.