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HELP REV Steven Hardy, January 1978 This procedure reverses the list given to it as argument. For example: rev([a b c d]) => ** [d c b a] rev([jack loves john]) => ** [john loves jack} rev([cities of england are [london leeds sheffield]]) => ** [[london leeds sheffield] are england of cities] Notice that REV does not reverse sub-lists. Here are some useful defintions using REV: define last(list); hd(rev(list)) enddefine; define butlast(list); rev(tl(rev(list))) enddefine; last([a b c d]) => ** d butlast([a b c d]) => ** [a b c] REV could be defined as: define rev(list); if list = [] then [] else rev(tl(list)) <> [% hd(list) %] endif enddefine; See also HELP * NCREV