ANSI Common Lisp   2 Syntax   2.4 Standard Macro Characters   2.4.8 Sharpsign

2.4.8.2 Sharpsign Single-Quote

Any expression preceded by #' (sharpsign followed by single-quote), as in #'expression, is treated by the Lisp reader as an abbreviation for and parsed identically to the expression (function expression). See function. For example,

(apply #'+ l) ==(apply (function +) l)