Scieneer Common Lisp 1.3.9 online documentation

gensym &optional thing[Function]

Creates a new uninterned symbol whose name is a prefix string (defaults to "g"), followed by a decimal number. When supplied, thing will alter the prefix if it is a string, or be used for the decimal number if it is a number, of this symbol. The default value of the number is the current value of *gensym-counter* which is incremented each time it is used.