The collect (or collecting) construct
takes one form in its clause
and adds the value of that form to the end of a list
of values. By default, the list of values is returned
when the loop finishes.
The append (or appending) construct
takes one form in its clause
and appends the value of that form to the end of a list
of values. By default, the list of values is returned when the
loop finishes.
The nconc (or nconcing) construct
is similar to the append construct,
but its list values are concatenated as if by the function
nconc. By default, the list of values is returned when
the loop finishes.
The sum (or summing) construct
takes one form in its clause
that must evaluate to a number and accumulates the sum of all these
numbers. By default, the cumulative sum is returned when the
loop finishes.
The count (or counting) construct
takes one form in its clause
and counts the number of times that the form evaluates to true.
By default, the count is returned when the loop finishes.
The minimize (or minimizing) construct
takes one form in its clause
and determines the minimum value obtained by evaluating that form.
By default, the minimum value is returned when the loop finishes.
The maximize (or maximizing) construct
takes one form in its clause
and determines the maximum value obtained by evaluating that form.
By default, the maximum value is returned when the loop finishes.
For more information, see Value Accumulation Clauses.