altos/lisp: Lots more scheme bits

[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
                                        ;

(set (quote define) (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)
                                        ;

(define defun (macro (name args exprs)
                  (list
                   define
                   name
                   (cons 'lambda (cons args 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 zero? (macro (value rest)
                     (list
                      eq?
                      value
                      0)
                     )
  )

(zero? 1)
(zero? 0)
(zero? "hello")

(define positive? (macro (value rest)
                         (list
                          >
                          value
                          0)
                         )
  )

(positive? 12)
(positive? -12)

(define negative? (macro (value rest)
                         (list
                          <
                          value
                          0)
                         )
  )

(negative? 12)
(negative? -12)

(defun abs (x) (cond ((>= x 0) x)
                     (else (- x)))
       )

(abs 12)
(abs -12)

(define max (lexpr (first rest)
                   (while (not (null? rest))
                     (cond ((< first (car rest))
                            (set! first (car rest)))
                           )
                     (set! rest (cdr rest))
                     )
                   first)
  )

(max 1 2 3)
(max 3 2 1)

(define min (lexpr (first rest)
                   (while (not (null? rest))
                     (cond ((> first (car rest))
                            (set! first (car rest)))
                           )
                     (set! rest (cdr rest))
                     )
                   first)
  )

(min 1 2 3)
(min 3 2 1)

(defun even? (x) (zero? (% x 2)))

(even? 2)
(even? -2)
(even? 3)
(even? -1)

(defun odd? (x) (not (even? x)))

(odd? 2)
(odd? -2)
(odd? 3)
(odd? -1)

(define exact? number?)
(defun inexact? (x) #f)

                                        ; (if <condition> <if-true>)
                                        ; (if <condition> <if-true> <if-false)

(define if (macro (test args)
               (cond ((null? (cdr args))
                      (list
                       cond
                       (list test (car args)))
                      )
                     (else
                      (list
                       cond
                       (list test (car args))
                       (list 'else (cadr args))
                       )
                      )
                     )
               )
     )

(if (> 3 2) 'yes)
(if (> 3 2) 'yes 'no)
(if (> 2 3) 'no 'yes)
(if (> 2 3) 'no)

                                        ; 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)) (set! y (+ x 1)) y)

(define let (macro (vars exprs)
                ((lambda (make-names make-exprs make-nils)

                                        ;
                                        ; make the list of names in the let
                                        ;

                   (set! make-names (lambda (vars)
                                      (cond ((not (null? 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

                   (set! make-exprs (lambda (vars exprs)
                                      (cond ((not (null? 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

                   (set! make-nils (lambda (vars)
                                     (cond ((not (null? vars)) (cons () (make-nils (cdr vars))))
                                           )
                                     )
                         )
                                        ; prepend the set operations
                                        ; to the expressions

                   (set! exprs (make-exprs vars exprs))

                                        ; build the lambda.

                   (cons (cons 'lambda (cons (make-names vars) exprs))
                         (make-nils vars)
                         )
                   )
                 ()
                 ()
                 ()
                 )
                )
     )

(let ((x 1)) x)

                                        ; boolean operators

(define or (lexpr (l)
               (let ((ret #f))
                 (while (not (null? l))
                   (cond ((car l) (set! ret #t) (set! l ()))
                         ((set! l (cdr l)))))
                 ret
                 )
               )
     )

                                        ; execute to resolve macros

(or #f #t)

(define and (lexpr (l)
               (let ((ret #t))
                 (while (not (null? l))
                   (cond ((car l)
                          (set! l (cdr l)))
                         (#t
                          (set! ret #f)
                          (set! l ()))
                         )
                   )
                 ret
                 )
               )
     )

                                        ; execute to resolve macros

(and #t #f)


(define append (lexpr (args)
                      (let ((append-list (lambda (a b)
                                           (cond ((null? a) b)
                                                 (else (cons (car a) (append-list (cdr a) b)))
                                                 )
                                           )
                                         )
                            (append-lists (lambda (lists)
                                            (cond ((null? lists) lists)
                                                  ((null? (cdr lists)) (car lists))
                                                  (else (append-list (car lists) (append-lists (cdr lists))))
                                                  )
                                            )
                                          )
                            )
                        (append-lists args)
                        )
                      )
  )

(append '(a b c) '(d e f) '(g h i))

(defun reverse (list)
  (let ((result ()))
    (while (not (null? list))
      (set! result (cons (car list) result))
      (set! list (cdr list))
      )
    result)
  )

(reverse '(1 2 3))

(define list-tail
  (lambda (x k)
    (if (zero? k)
        x
      (list-tail (cdr x) (- k 1)))))

(list-tail '(1 2 3) 2)
                                        ; recursive equality

(defun equal? (a b)
  (cond ((eq? a b) #t)
        ((and (pair? a) (pair? b))
         (and (equal? (car a) (car b))
              (equal? (cdr a) (cdr b)))
         )
        (else #f)
        )
  )

(equal? '(a b c) '(a b c))
(equal? '(a b c) '(a b b))

;(define number->string (lexpr (arg opt)
;                             (let ((base (if (null? opt) 10 (car opt)))
                                        ;
;