r5rs

I'm beginner in ANTLR and I'm learning it by an example. I use C as my target language. The example is a Scheme R5RS grammar file taken from this question , with a little modification(rename the grammar name and add some options with the grammar specification untouched). antlr generated the lexer and parser, and I compile it with a test main() in which I just do some initialization and simply call the parser. When runing the test program with a piece of scheme code, the parser detect some syntax error(which should not happen!) main function in test.c #include <stdio.h> #include "r5rsLexer.h"

For example: if I want the function equal? recognize my own type or record, can I add a new behavior of equal? ? without erasing or overwriting the old one? Or for example if I want to make the function "+" accept also string? Rather than using import , a better solution is to keep track of the original function by let -binding it. It's also better to check that the type of the argument is a string, rather than that it is not a number. Using both of these approaches means that it's possible to compose the technique. (define + (let ((old+ +)) (lambda args (if (string? (car args)) (apply string

Inspired by a comment thread on a related question regarding functions instead of macros. Is there any way to extend a Scheme syntax definition so that it can use the previous definition of the syntax in the new definition? Furthermore, this must be extensible, that is, it must be possible to chain the technique together several times. For example, say we want to extend lambda so that every time a function defined with lambda is called, it prints "foo" before executing the function body. We can do this in the following way: (define-syntax old-lambda lambda) (define-syntax lambda (syntax-rules

This is concerning chapter 3.5 from SICP, in which streams are being discussed. The idea is that: (cons-stream 1 (display 'hey)) Should not evaluate the second part of the cons-stream, so it should not print “hey”. This does happen, I get the following output: hey(1 . #< promise >) So my conclusion is that delay is not implemented as a special form? Or am I doing something wrong? I use the following implementation: (define (cons-stream a b) (cons a (delay b))) With delay being the default R5RS implementation. Is this a fault in the implementation, or am I not doing or understanding it right?

I need a subroutine for my program written in scheme that takes an integer, say 34109, and puts it into a list with elements 3, 4, 1, 0, 9. The integer can be any length. Does anyone have a trick for this? I've thought about using modulo for every place, but I don't think it should be that complicated. The simplest way I can think of, is by using arithmetic operations and a named let for implementing a tail-recursion: (define (number->list num) (let loop ((num num) (acc '())) (if (< num 10) (cons num acc) (loop (quotient num 10) (cons (remainder num 10) acc))))) Alternatively, you can solve