15.25.11.1 do - doing

do {expr}*
doing {expr}*

‘do’ ¶

construct simply evaluates the specified expressions wherever they occur in the expanded form of loop.

expr

argument can be any non-atomic Common Lisp form. Each expr is evaluated in every iteration.

Constructs with Arbitraty Number of Forms

The constructs

• ‘do’,
• ‘initially’, and
• ‘finally’

are the only loop keywords that take an arbitrary number of forms and group them as if using an implicit progn.

Because every loop clause must begin with a loop keyword, you would use the keyword ‘do’ when no control action other than execution is required.

Examples

;;; Print some numbers.
(loop for i from 1 to 5
      do (print i)) ;Prints 5 lines

;;; Print numbers and their squares.
;;; The DO construct applies to multiple forms.
(loop for i from 1 to 4
      do (print i)
         (print (* i i))) ;Prints 8 lines