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From: Lauri Alanko <la@xxxxxx> Date: Sun, 5 Mar 2006 11:44:17 +0200 On Sun, Mar 05, 2006 at 10:34:21AM +0100, Chris Hanson wrote: > Although the original language specification, "scheme://r6rs", looks > vaguely like a URI, it's not correctly formed (see > "http://www.ietf.org/rfc/rfc3986.txt";). Huh? I see: URI = scheme ":" hier-part [ "?" query ] [ "#" fragment ] scheme = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." ) hier-part = "//" authority path-abempty path-abempty = *( "/" segment ) authority = [ userinfo "@" ] host [ ":" port ] host = IP-literal / IPv4address / reg-name reg-name = *( unreserved / pct-encoded / sub-delims ) unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~" 3.2.2 additionally notes that reg-name can use a custom namespace: A host identified by a registered name is a sequence of characters usually intended for lookup within a locally defined host or service name registry, though the URI's scheme-specific semantics may require that a specific registry (or fixed name table) be used instead. So, apart from using an unregistered scheme, it is a real URI. Ah -- I forgot about the reg-name thing. Which is strange since I implemented a URI parser just a year ago, and it handles reg-name exactly as it should. I should have just typed that string at the parser to see what it did. Nevertheless I still think it's a mistake to use a custom URI scheme for this purpose, even if it's registered. The important thing to remember is that a URI is just a string with a funny syntax. Meaning is imposed by context and usage, not by the URI scheme in use. Some URIs need distinguished schemes because they identify particular transport protocols, but the SRFI-83 application doesn't involve network transport and consequently doesn't need any particular scheme. For background: I'm approaching this from the context of the Semantic Web. In that world, URIs are just strings, and their meaning is defined by their relationships to other URIs (usually written in RDF). The fact that you might be able to dereference one of these strings to provide a document is incidental. When used at all, it's just a mechanism to retrieve the documents containing the RDF. In the Semantic Web, the URI plays the same role that the symbol does in Lisp. Chris PS: Please CC me on any reply. I'm not reading this list.