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|
;
; 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 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)
(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))
|
