The group statement is a construct used where REDUCE expects a single statement, but a series of actions needs to be performed. It is formed by enclosing one or more statements (of any kind) between the symbols << and >>, separated by semicolons or dollar signs – it doesn’t matter which. The statements are executed one after another.
Examples will be given in the sections on IF and other types of statements in which the <<…>> construct is useful.
If the last statement in the enclosed group has a value, then that is also the value of the group statement. Care must be taken not to have a semicolon or dollar sign after the last grouped statement, if the value of the group is relevant: such an extra terminator causes the group to have the value NIL or zero.