15.25.6.9 ’repeat’

repeat expr

The ‘repeat’ construct causes iteration to terminate after a specified number of times. The loop body is executed n times, where n is the value of the expression expr. The expr argument is evaluated one time in the loop prologue. If the expression evaluates to zero or to a negative number, the loop body is not evaluated.

The clause ‘repeat’ n is roughly equivalent to a clause such as

for internal-variable downfrom (- n 1) to 0

but, in some implementations, the ‘repeat’ construct might be more efficient.

(loop repeat 3 ;Prints 3 lines
      do (format t "What I say three times is true~%"))

(loop repeat -15 ;Prints nothing
      do (format t "What you see is what you expect~%"))