+++ /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.
-;
-; Advanced syntax, including vectors and floats
-
-(begin
- (def! equal?
- (lambda (a b)
- (cond ((eq? a b) #t)
- ((and (pair? a) (pair? b))
- (and (equal? (car a) (car b))
- (equal? (cdr a) (cdr b)))
- )
- ((and (vector? a) (vector? b) (= (vector-length a) (vector-length b)))
- ((lambda (i l)
- (while (and (< i l)
- (equal? (vector-ref a i)
- (vector-ref b i)))
- (set! i (+ i 1)))
- (eq? i l)
- )
- 0
- (vector-length a)
- )
- )
- (else #f)
- )
- )
- )
- 'equal?
- )
-
-(equal? '(a b c) '(a b c))
-(equal? '(a b c) '(a b b))
-(equal? #(1 2 3) #(1 2 3))
-(equal? #(1 2 3) #(4 5 6))
-
-(define quasiquote
- (macro (x)
- (define (constant? exp)
- ; A constant value is either a pair starting with quote,
- ; or anything which is neither a pair nor a symbol
-
- (cond ((pair? exp)
- (eq? (car exp) 'quote)
- )
- (else
- (not (symbol? exp))
- )
- )
- )
-
- (define (combine-skeletons left right exp)
- (cond
- ((and (constant? left) (constant? right))
- (cond ((and (eqv? (eval left) (car exp))
- (eqv? (eval right) (cdr exp)))
- (list 'quote exp)
- )
- (else
- (list 'quote (cons (eval left) (eval right)))
- )
- )
- )
- ((null? right)
- (list 'list left)
- )
- ((and (pair? right) (eq? (car right) 'list))
- (cons 'list (cons left (cdr right)))
- )
- (else
- (list 'cons left right)
- )
- )
- )
-
- (define (expand-quasiquote exp nesting)
- (cond
-
- ; non cons -- constants
- ; themselves, others are
- ; quoted
-
- ((not (pair? exp))
- (cond ((constant? exp)
- exp
- )
- (else
- (list 'quote exp)
- )
- )
- )
-
- ; check for an unquote exp and
- ; add the param unquoted
-
- ((and (eq? (car exp) 'unquote) (= (length exp) 2))
- (cond ((= nesting 0)
- (car (cdr exp))
- )
- (else
- (combine-skeletons ''unquote
- (expand-quasiquote (cdr exp) (- nesting 1))
- exp))
- )
- )
-
- ; nested quasi-quote --
- ; construct the right
- ; expression
-
- ((and (eq? (car exp) 'quasiquote) (= (length exp) 2))
- (combine-skeletons ''quasiquote
- (expand-quasiquote (cdr exp) (+ nesting 1))
- exp))
-
- ; check for an
- ; unquote-splicing member,
- ; compute the expansion of the
- ; value and append the rest of
- ; the quasiquote result to it
-
- ((and (pair? (car exp))
- (eq? (car (car exp)) 'unquote-splicing)
- (= (length (car exp)) 2))
- (cond ((= nesting 0)
- (list 'append (car (cdr (car exp)))
- (expand-quasiquote (cdr exp) nesting))
- )
- (else
- (combine-skeletons (expand-quasiquote (car exp) (- nesting 1))
- (expand-quasiquote (cdr exp) nesting)
- exp))
- )
- )
-
- ; for other lists, just glue
- ; the expansion of the first
- ; element to the expansion of
- ; the rest of the list
-
- (else (combine-skeletons (expand-quasiquote (car exp) nesting)
- (expand-quasiquote (cdr exp) nesting)
- exp)
- )
- )
- )
- (expand-quasiquote x 0)
- )
- )
-
- ; `q -> (quote q)
- ; `(q) -> (append (quote (q)))
- ; `(a ,(+ 1 2)) -> (append (quote (a)) (list (+ 1 2)))
- ; `(a ,@(list 1 2 3) -> (append (quote (a)) (list 1 2 3))
-
-
-`(hello ,(+ 1 2) ,@(list 1 2 3) `foo)
-
- ; define a set of local
- ; variables all at once 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)
- (define (make-names vars)
- (cond ((not (null? vars))
- (cons (car (car vars))
- (make-names (cdr vars))))
- (else ())
- )
- )
-
- ; the parameters to the lambda is a list
- ; of nils of the right length
-
- (define (make-vals vars)
- (cond ((not (null? vars))
- (cons (cond ((null? (cdr (car vars))) ())
- (else
- (car (cdr (car vars))))
- )
- (make-vals (cdr vars))))
- (else ())
- )
- )
- ; prepend the set operations
- ; to the expressions
-
- ; build the lambda.
-
- `((lambda ,(make-names vars) ,@exprs) ,@(make-vals vars))
- )
- )
-
-
-(let ((x 1) (y)) (set! y 2) (+ x y))
-
-(define assv assq)
-
-(assv 'b '((a 1) (b 2) (c 3)))
-
-(define when (macro (test . l) `(cond (,test ,@l))))
-
-(when #t (+ 1 2))
-(when #f (+ 1 2))
-
-(define unless (macro (test . l) `(cond ((not ,test) ,@l))))
-
-(unless #f (+ 2 3))
-(unless #t (+ 2 3))
-
-(define (cdar l) (cdr (car l)))
-
-(cdar '((1 2) (3 4)))
-
-(define (cddr l) (cdr (cdr l)))
-
-(cddr '(1 2 3))
-
-(define (caddr l) (car (cdr (cdr l))))
-
-(caddr '(1 2 3 4))
-
-(define (reverse list)
- (define (_r old new)
- (if (null? old)
- new
- (_r (cdr old) (cons (car old) new))
- )
- )
- (_r list ())
- )
-
-(reverse '(1 2 3))
-
-(define make-list
- (lambda (a . b)
- (define (_m a x)
- (if (zero? a)
- x
- (_m (- a 1) (cons b x))
- )
- )
- (if (null? b)
- (set! b #f)
- (set! b (car b))
- )
- (_m a '())
- )
- )
-
-(make-list 10 'a)
-
-(make-list 10)
-
-(define for-each
- (lambda (proc . lists)
- (define (_f lists)
- (cond ((null? (car lists)) #t)
- (else
- (apply proc (map car lists))
- (_f (map cdr lists))
- )
- )
- )
- (_f lists)
- )
- )
-
-(let ((a 0))
- (for-each (lambda (b) (set! a (+ a b))) '(1 2 3))
- a
- )
-
-(call-with-current-continuation
- (lambda (exit)
- (for-each (lambda (x)
- (if (negative? x)
- (exit x)))
- '(54 0 37 -3 245 19))
- #t))
-
-(define case
- (macro (test . l)
- ; construct the body of the
- ; case, dealing with the
- ; lambda version ( => lambda)
-
- (define (_unarrow l)
- (cond ((null? l) l)
- ((eq? (car l) '=>) `(( ,(cadr l) __key__)))
- (else l))
- )
-
- ; Build the case elements, which is
- ; simply a list of cond clauses
-
- (define (_case l)
-
- (cond ((null? l) ())
-
- ; else case
-
- ((eq? (caar l) 'else)
- `((else ,@(_unarrow (cdr (car l))))))
-
- ; regular case
-
- (else
- (cons
- `((eqv? ,(caar l) __key__)
- ,@(_unarrow (cdr (car l))))
- (_case (cdr l)))
- )
- )
- )
-
- ; now construct the overall
- ; expression, using a lambda
- ; to hold the computed value
- ; of the test expression
-
- `((lambda (__key__)
- (cond ,@(_case l))) ,test)
- )
- )
-
-(case 1 (1 "one") (2 "two") (3 => (lambda (x) (write (list "the value is" x)))) (12 "twelve") (else "else"))
-(case 2 (1 "one") (2 "two") (3 => (lambda (x) (write (list "the value is" x)))) (12 "twelve") (else "else"))
-(case 3 (1 "one") (2 "two") (3 => (lambda (x) (write (list "the value is" x)) "three")) (12 "twelve") (else "else"))
-(case 4 (1 "one") (2 "two") (3 => (lambda (x) (write (list "the value is" x)))) (12 "twelve") (else "else"))
-(case 12 (1 "one") (2 "two") (3 => (lambda (x) (write (list "the value is" x)))) (12 "twelve") (else "else"))
-
-(define do
- (macro (vars test . cmds)
- (define (_step v)
- (if (null? v)
- '()
- (if (null? (cddr (car v)))
- (_step (cdr v))
- (cons `(set! ,(caar v) ,(caddr (car v)))
- (_step (cdr v))
- )
- )
- )
- )
- `(let ,(map (lambda (v) (list (car v) (cadr v))) vars)
- (while (not ,(car test))
- ,@cmds
- ,@(_step vars)
- )
- ,@(cdr test)
- )
- )
- )
-
-(do ((x 1 (+ x 1))
- (y 0)
- )
- ((= x 10) y)
- (set! y (+ y x))
- )
projects / fw / altos / blobdiff