pLISP © '98 Thomas Mahler

Libray of basic Lisp functions

Some useful macros

 // apply applies function fun to its arguments args
 // E.g. (apply a ´(3 3))
 (define apply
   (macro (fun args) (cons fun (eval args) ) ))



 // defun is used to define functions in lisp style
 // and immediately compiles the new function
 (define defun (macro (fun args body)
  (cons 'progn (cons
        // build lambda definition:
        (cons 'setq (cons fun  (cons (cons 'lambda (cons args (cons body nil) ))nil)) )
        // call cf to compile fun:
        //(cons (cons 'cf (cons (cons 'quote (cons fun nil) )nil) ) nil)
        nil
  )))) 	


 // define factorial in defun syntax:
 (defun fac (n)	
 	(if (= n 0)
 		1
 		(* n (fac (-1 n)))))

logical operations and sets

 // test if predicate P is valid for all elements of set
 (defun forall (P set)
   (if (atomp args) 1
     (and (P (car set)) (forall P (cdr set))))) 

 // test if predicate P is valid for at least one element of set
 (defun exists (P set)
   (if (atomp args) 0
     (or (P (car set)) (exists P (cdr set))))) 

higher order functions

 // mapcar applies function fun to all elements in args and returns the listed results
 (defun mapcar (fun args)
	 (if (atomp args) args
      (cons (fun (car args)) (mapcar fun (cdr args)))))