On 9 Sep 2013, at 12:59, Costello, Roger L. wrote:
> Hi Folks,
>
> This is a programming language:
>
> <Book>
> <Title>____</Title>
> <Author>____</Author>
> </Book>
>
> Don't let the angle brackets and element names deceive you, it is a programming language.
>
> When I execute this program
>
> <Book>
> <Title>Six Great Ideas</Title>
> <Author>Mortimer Adler</Author>
> </Book>
>
Hang on, first you tell us that this snippet is a programming language, then you tell us it's a program.
Well, it's easy to see how it is a program. "Beam me up, Scotty" is a program if someone designs a programming language that includes this as one of its permitted constructions, and if the language defines semantics for this sentence. For any string of characters, you can design a programming language in which that string of characters is a program. So you can certainly design a programming language in which your <Book>..</Book> sample is a program. It only becomes an interesting programming language if it is suitable for writing a sufficiently general class of programs, and that's something you have yet to demonstrate.
Michael Kay
Saxonica
