--- /dev/null
+;
+; Copyright © 2018 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.
+;
+; Basic syntax placed in ROM
+
+(def (quote _?_) (lambda (a b) (cond ((eq? a b) a) (else (exit 1)))))
+
+(def (quote list) (lambda l l))
+
+(def (quote def!)
+ (macro (a b)
+ (list
+ def
+ (list quote a)
+ b)
+ )
+ )
+
+(begin
+ (def! append
+ (lambda args
+ (def! _a
+ (lambda (a b)
+ (cond ((null? a) b)
+ (else (cons (car a) (_a (cdr a) b)))
+ )
+ )
+ )
+
+ (def! _b
+ (lambda (l)
+ (cond ((null? l) l)
+ ((null? (cdr l)) (car l))
+ (else (_a (car l) (_b (cdr l))))
+ )
+ )
+ )
+ (_b args)
+ )
+ )
+ 'append)
+
+(append '(a) '(b))
+
+
+ ;
+ ; Define a variable without returning the value
+ ; Useful when defining functions to avoid
+ ; having lots of output generated.
+ ;
+ ; Also accepts the alternate
+ ; form for defining lambdas of
+ ; (define (name x y z) sexprs ...)
+ ;
+
+(begin
+ (def! define
+ (macro (a . b)
+ ; check for alternate lambda definition form
+
+ (cond ((pair? a)
+ (set! b
+ (cons
+ lambda
+ (cons (cdr a) b)))
+ (set! a (car a))
+ )
+ (else
+ (set! b (car b))
+ )
+ )
+ (cons begin
+ (cons
+ (cons def
+ (cons (cons quote (cons a '()))
+ (cons b '())
+ )
+ )
+ (cons
+ (cons quote (cons a '()))
+ '())
+ )
+ )
+ )
+ )
+ 'define
+ )
+ ; boolean operators
+
+(define or
+ (macro a
+ (def! b
+ (lambda (a)
+ (cond ((null? a) #f)
+ ((null? (cdr a))
+ (car a))
+ (else
+ (list
+ cond
+ (list
+ (car a))
+ (list
+ 'else
+ (b (cdr a))
+ )
+ )
+ )
+ )
+ )
+ )
+ (b a)))
+
+ ; execute to resolve macros
+
+(_?_ (or #f #t) #t)
+
+(define and
+ (macro a
+ (def! b
+ (lambda (a)
+ (cond ((null? a) #t)
+ ((null? (cdr a))
+ (car a))
+ (else
+ (list
+ cond
+ (list
+ (car a)
+ (b (cdr a))
+ )
+ )
+ )
+ )
+ )
+ )
+ (b a)
+ )
+ )
+
+ ; execute to resolve macros
+
+(_?_ (and #t #f) #f)
+
+ ; (if <condition> <if-true>)
+ ; (if <condition> <if-true> <if-false)
+
+(define if
+ (macro (a . b)
+ (cond ((null? (cdr b))
+ (list cond (list a (car b)))
+ )
+ (else
+ (list cond
+ (list a (car b))
+ (list 'else (car (cdr b)))
+ )
+ )
+ )
+ )
+ )
+
+(_?_ (if (> 3 2) 'yes) 'yes)
+(_?_ (if (> 3 2) 'yes 'no) 'yes)
+(_?_ (if (> 2 3) 'no 'yes) 'yes)
+(_?_ (if (> 2 3) 'no) #f)
+
+(define letrec
+ (macro (a . b)
+
+ ;
+ ; make the list of names in the let
+ ;
+
+ (define (_a a)
+ (cond ((not (null? a))
+ (cons (car (car a))
+ (_a (cdr a))))
+ (else ())
+ )
+ )
+
+ ; the set of expressions is
+ ; the list of set expressions
+ ; pre-pended to the
+ ; expressions to evaluate
+
+ (define (_b a b)
+ (cond ((null? a) b)
+ (else
+ (cons
+ (list set
+ (list quote
+ (car (car a))
+ )
+ (cond ((null? (cdr (car a)))
+ ()
+ )
+ (else
+ (car (cdr (car a)))
+ )
+ )
+ )
+ (_b (cdr a) b)
+ )
+ )
+ )
+ )
+
+ ; the parameters to the lambda is a list
+ ; of nils of the right length
+
+ (define (_c a)
+ (cond ((null? a) ())
+ (else (cons () (_c (cdr a))))
+ )
+ )
+ ; build the lambda.
+
+ (cons (cons lambda (cons (_a a) (_b a b))) (_c a))
+ )
+ )
+
+(_?_ (letrec ((a 1) (b a)) (+ a b)) 2)
+
+ ; letrec is sufficient for let*
+
+(define let* letrec)
+
+ ; use letrec for let in basic
+ ; syntax
+
+(define let letrec)
+
+ ; Basic recursive
+ ; equality. Replaced with
+ ; vector-capable version in
+ ; advanced syntax
+
+(define (equal? a b)
+ (cond ((eq? a b) #t)
+ ((pair? a)
+ (cond ((pair? b)
+ (cond ((equal? (car a) (car b))
+ (equal? (cdr a) (cdr b)))
+ )
+ )
+ )
+ )
+ )
+ )
+
+(_?_ (equal? '(a b c) '(a b c)) #t)
+(_?_ (equal? '(a b c) '(a b b)) #f)
+
+(def (quote _??_) (lambda (a b) (cond ((equal? a b) a) (else (exit 1)))))
+
+ ; basic list accessors
+
+(define (caar a) (car (car a)))
+
+(define (cadr a) (car (cdr a)))
+
+(define (cdar l) (cdr (car l)))
+
+(_??_ (cdar '((1 2) (3 4))) '(2))
+
+(define (cddr l) (cdr (cdr l)))
+
+(_??_ (cddr '(1 2 3)) '(3))
+
+(define (caddr l) (car (cdr (cdr l))))
+
+(_??_ (caddr '(1 2 3 4)) 3)
+
+(define (list-ref a b)
+ (car (list-tail a b))
+ )
+
+(list-ref '(1 2 3) 2)
+
+(define (member a b . t?)
+ (cond ((null? b)
+ #f
+ )
+ (else
+ (if (null? t?) (set! t? equal?) (set! t? (car t?)))
+ (if (t? a (car b))
+ b
+ (member a (cdr b) t?))
+ )
+ )
+ )
+
+(_??_ (member '(2) '((1) (2) (3))) '((2) (3)))
+(_??_ (member '(4) '((1) (2) (3))) #f)
+
+(define (memq a b) (member a b eq?))
+
+(_??_ (memq 2 '(1 2 3)) '(2 3))
+(_??_ (memq 4 '(1 2 3)) #f)
+(_??_ (memq '(2) '((1) (2) (3))) #f)
+
+(define (assoc a b . t?)
+ (if (null? t?)
+ (set! t? equal?)
+ (set! t? (car t?))
+ )
+ (if (null? b)
+ #f
+ (if (t? a (caar b))
+ (car b)
+ (assoc a (cdr b) t?)
+ )
+ )
+ )
+
+(define (assq a b) (assoc a b eq?))
+(define assv assq)
+
+(_??_ (assq 'a '((a 1) (b 2) (c 3))) '(a 1))
+(_??_ (assv 'b '((a 1) (b 2) (c 3))) '(b 2))
+(_??_ (assoc '(c) '((a 1) (b 2) ((c) 3))) '((c) 3))
+
+(define map
+ (lambda (proc . lists)
+ (define (_a lists)
+ (cond ((null? lists) ())
+ (else
+ (cons (caar lists) (_a (cdr lists)))
+ )
+ )
+ )
+ (define (_n lists)
+ (cond ((null? lists) ())
+ (else
+ (cons (cdr (car lists)) (_n (cdr lists)))
+ )
+ )
+ )
+ (define (_m lists)
+ (cond ((null? (car lists)) ())
+ (else
+ (cons (apply proc (_a lists)) (_m (_n lists)))
+ )
+ )
+ )
+ (_m lists)
+ )
+ )
+
+(_??_ (map cadr '((a b) (d e) (g h))) '(b e h))
+
+ ; use map as for-each in basic
+ ; mode
+
+(define for-each map)
+ ; simple math operators
+
+(define zero? (macro (value) (list eq? value 0)))
+
+(zero? 1)
+(zero? 0)
+(zero? "hello")
+
+(define positive? (macro (value) (list > value 0)))
+
+(positive? 12)
+(positive? -12)
+
+(define negative? (macro (value) (list < value 0)))
+
+(negative? 12)
+(negative? -12)
+
+(define (abs a) (if (>= a 0) a (- a)))
+
+(abs 12)
+(abs -12)
+
+(define max (lambda (a . b)
+ (while (not (null? b))
+ (cond ((< a (car b))
+ (set! a (car b)))
+ )
+ (set! b (cdr b))
+ )
+ a)
+ )
+
+(max 1 2 3)
+(max 3 2 1)
+
+(define min (lambda (a . b)
+ (while (not (null? b))
+ (cond ((> a (car b))
+ (set! a (car b)))
+ )
+ (set! b (cdr b))
+ )
+ a)
+ )
+
+(min 1 2 3)
+(min 3 2 1)
+
+(define (even? a) (zero? (% a 2)))
+
+(even? 2)
+(even? -2)
+(even? 3)
+(even? -1)
+
+(define (odd? a) (not (even? a)))
+
+(odd? 2)
+(odd? -2)
+(odd? 3)
+(odd? -1)
+
+(define (newline) (write-char #\newline))
+
+(newline)
+
+(define (eof-object? a)
+ (equal? a 'eof)
+ )
+
projects / fw / altos / blobdiff