Common Lisp the Language, 2nd Edition
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Execution
The Loop Facility provides the named
construct to name a
loop so that the Common Lisp special form return-from
can
be used.
The loop keywords initially
and finally
designate loop constructs that cause expressions to be evaluated before
and after the loop body, respectively.
The code for any initially
clauses is collected into one
progn
in the order in which the clauses appeared in the
loop. The collected code is executed once in the loop prologue after any
implicit variable initializations.
The code for any finally
clauses is collected into one
progn
in the order in which the clauses appeared in the
loop. The collected code is executed once in the loop epilogue before
any implicit values are returned from the accumulation clauses. Explicit
returns in the loop body, however, will exit the loop without executing
the epilogue code.
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