Re: 3DLDF

[Laurence Finston]

Hans Aberg wrote:

> 
> You do just about what I thought. You could fairly easily make such an
> intermediate language, as I suggested. The point is that you, and any
> potential users, would be freed from the cumbersome C++ syntax.
> 

The manual and the pretty-printed source code downloadable from the 
website document 3DLDF 1.1.5.1, which is non-interactive.  I'm currently
working on the next release, which is interactive and includes a Bison parser.
  Once it's released, users of 3DLDF will no longer need to write C++ code and
rebuild the executable in order to use the package.  This also implies that I
will have to completely rewrite the introductory chapters of the manual.  

I appreciate your suggestions, but I don't see any advantage to coding an
intermediate language.  I believe that a Metafont-like language will 
provide all the generality and convenience I need, and that a machine-like
language is most suitable for cases where efficiency is paramount and code can
be generated automatically.  I designed the types 
and functions  defined in 3DLDF with the Metafont-language in mind.  Hence
`Point' in the C++ code corresponds to `point' in the 3DLDF language, `Path'
to `path', etc.

You might find it interesting to look at Metafont's grammar.  Knuth 
describes it using Backus-Naur form in _The METAFONTbook_, especially chapters
25 and 26.  It's very clever and well thought out.  I never really understood
it (or even tried to) until I started using it as the basis of my Bison
grammar.  

Laurence