[ 源代码： cl-iterate ]
软件包：cl-iterate（20180228-1）
Jonathan Amsterdam's Common Lisp iterator/gatherer/accumulator facility
iterate is an iteration construct for Common Lisp. It is similar to the CL:LOOP macro, with these distinguishing marks:
it is extensible, it helps editors like Emacs indent iterate forms by having a more lisp-like syntax, and it isn't part of the ANSI standard for Common Lisp (which is sometimes a bad thing and sometimes good).