object identity, 123
object-oriented programming, 205, 238
objects, 3
occur free, 27, 29
odd?, 45, 63, 78, 145
open-input-file, 171
open-output-file, 175
operating system, 253, 258
operations on objects, 121
operator precedence, 16
or, 34, 35, 61, 98
order of evaluation, 22, 95
output-port?, 175