(font-lock-add-keywords                                                                                                                                                                                                             
           'espresso-mode `(("\\(function *\\)("                                                                                                                                                                     
                             (0 (progn (compose-region (match-beginning 1)                                                                                                                                                                    
                                                       (match-end 1) "ƒ")                                                                                                                                                                     
                                       nil)))))