REF EVALUATOR Titch Le Bek, Rob Duncan, 1986 COPYRIGHT University of Sussex 1993. All Rights Reserved. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> <<<<<<<<<<<<<<<<<<<<< >>>>>>>>>>>>>>>>>>>>>> <<<<<<<<<<<<<<<<<<<<< LISP EVALUATION PROCEDURES >>>>>>>>>>>>>>>>>>>>>> <<<<<<<<<<<<<<<<<<<<< >>>>>>>>>>>>>>>>>>>>>> <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< This file briefly describes the functions, variables and constants documented in Chapter 20 of the standard Common Lisp guide, which is: Common Lisp: The Language (Guy L. Steele, Digital Press, 1984). ------------------------------------------------- 1 A Listing of Functions Variables and Constants ------------------------------------------------- + [variable] ++ [variable] +++ [variable] While a form is being evaluated by the top-level loop, the variable + is bound to the previous form read by the loop. The variable ++ holds the previous value of + (that is, the form evaluated two interactions ago), and +++ holds the previous value of ++. - [variable] While a form is being evaluated by the top-level loop, the variable - is bound to the form itself; that is, it is the value about to be given to + once this interaction is done. * [variable] ** [variable] *** [variable] While a form is being evaluated by the top-level loop, the variable * is bound to the result printed at the end of the last time through the loop; that is, it is the value produced by evaluating the form in +. If several values were produced, * contains the first value only; * contains nil if zero values were produced. The variable ** holds the previous value of * (that is, the result printed two interactions ago), and *** holds the previous value of **. / [variable] // [variable] /// [variable] While a form is being evaluated by the top-level loop, the variable / is bound to a list of the results printed at the end of the last time through the loop; that is, it is a list of all values produced by evaluating the form in +. The value of * should always be the same as the car of the value of /. The variable // holds the previous value of / (that is, the results printed two interactions ago), and /// holds the previous value of //. Therefore the value of ** should always be the same as the car of //, and similarly for *** and ///. (constantp object) [function] Returns true if object is a constant (i. e. always evaluates to the same thing); nil otherwise. (eval form) [function] Returns the result of evaluating form in the null lexical environment. --- C.all/lisp/ref/evaluator --- Copyright University of Sussex 1993. All rights reserved.