[fw/altos] / src / lisp / ao_lisp_const.lisp

;
; Copyright © 2016 Keith Packard <keithp@keithp.com>
;
; This program is free software; you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation, either version 2 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful, but
; WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
; General Public License for more details.
;
; Lisp code placed in ROM

                                        ; return a list containing all of the arguments

(set (quote list) (lexpr (l) l))

                                        ;
                                        ; Define a variable without returning the value
                                        ; Useful when defining functions to avoid
                                        ; having lots of output generated
                                        ;

(setq def (macro (name val rest)
                 (list
                  'progn
                  (list
                   'set
                   (list 'quote name)
                   val)
                  (list 'quote name)
                  )
                 )
      )

                                        ;
                                        ; A slightly more convenient form
                                        ; for defining lambdas.
                                        ;
                                        ; (defun <name> (<params>) s-exprs)
                                        ;

(def defun (macro (name args exprs)
                  (list
                   def
                   name
                   (list
                    'lambda
                    args
                    (cond ((cdr exprs)
                           (cons progn exprs))
                          ((car exprs))
                          )
                    )
                   )
                  )
     )
                                        ; basic list accessors


(defun cadr (l) (car (cdr l)))

(defun caddr (l) (car (cdr (cdr l))))

(defun nth (list n)
  (cond ((= n 0) (car list))
        ((nth (cdr list) (1- n)))
        )
  )

                                        ; simple math operators

(defun 1+ (x) (+ x 1))
(defun 1- (x) (- x 1))

                                        ; define a set of local
                                        ; variables and then evaluate
                                        ; a list of sexprs
                                        ;
                                        ; (let (var-defines) sexprs)
                                        ;
                                        ; where var-defines are either
                                        ;
                                        ; (name value)
                                        ;
                                        ; or
                                        ;
                                        ; (name)
                                        ;
                                        ; e.g.
                                        ;
                                        ; (let ((x 1) (y)) (setq y (+ x 1)) y)

(def let (macro (vars exprs)
                ((lambda (make-names make-exprs make-nils)
                   (progn

                                        ;
                                        ; make the list of names in the let
                                        ;

                     (setq make-names (lambda (vars)
                                       (cond (vars
                                              (cons (car (car vars))
                                                    (make-names (cdr vars))))
                                             )
                                       )
                          )

                                        ; the set of expressions is
                                        ; the list of set expressions
                                        ; pre-pended to the
                                        ; expressions to evaluate

                     (setq make-exprs (lambda (vars exprs)
                                       (progn
                                         (cond (vars (cons
                                                      (list set
                                                            (list quote
                                                                  (car (car vars))
                                                                  )
                                                            (cadr (car vars))
                                                            )
                                                      (make-exprs (cdr vars) exprs)
                                                      )
                                                     )
                                               (exprs)
                                               )
                                         )
                                       )
                          )

                                        ; the parameters to the lambda is a list
                                        ; of nils of the right length

                     (setq make-nils (lambda (vars)
                                      (cond (vars (cons nil (make-nils (cdr vars))))
                                            )
                                      )
                          )
                                        ; prepend the set operations
                                        ; to the expressions

                     (setq exprs (make-exprs vars exprs))

                                        ; build the lambda.

                     (cons
                      (list
                       'lambda
                       (make-names vars)
                       (cond ((cdr exprs) (cons 'progn exprs))
                             ((car exprs))
                             )
                       )
                      (make-nils vars)
                      )
                     )
                   )
                 ()
                 ()
                 ()
                 )
                )
     )

                                        ; boolean operators

(def or (lexpr (l)
               (let ((ret nil))
                 (while l
                   (cond ((setq ret (car l))
                          (setq l nil))
                         ((setq l (cdr l)))))
                 ret
                 )
               )
     )

                                        ; execute to resolve macros

(or nil t)

(def and (lexpr (l)
               (let ((ret t))
                 (while l
                   (cond ((setq ret (car l))
                          (setq l (cdr l)))
                         ((setq ret (setq l nil)))
                         )
                   )
                 ret
                 )
               )
     )

                                        ; execute to resolve macros

(and t nil)