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When fine control is desired over where code appears in a loop
generated by iterate
, the following special clauses may be useful.
They are all subject to code-motion problems (see Problems with Code Movement).
&rest
formsThe lisp forms are placed in the prologue section of the loop, where they are executed once, before the loop body is entered.
&rest
formsThe forms are placed at the end of the loop body, where they are executed after each iteration. Unlike the other clauses in this section, forms may contain
iterate
clauses.
&rest
formsThe lisp forms are placed in the epilogue section of the loop, where they are executed if this
else
clause is never met during execution of the loop and the loop terminates normally.