Matching templates against a tree - any idea?

[Amit Patel]

 Jon Fernquest <ferni at loxinfo.co.th> wrote:
| Fernando Pereira wrote:
| 
| Thanks for making the posting on term rewriting systems.
| 
| 1. Do you think it's possible to make a rewriting system extension 
| to an existing language like Python or Perl?
| 
| Everything seems to be in ML and ML extensions such as
| Isabelle right now. It's so easy to cook up (or integrate 
| components into) whole systems in Python 
| (or Perl) and since so many people use them in their
| day to day work modules have a greater chance of being used.

ML already has some pattern-matching constructs that can be used to
match subtrees.  For example, this tree:

         Mul
         / \
       Add  B
       / \
      A   0

can be matched like this:

  case(tree) of
     Mul(Add(A,Num(0)), B) =>   ... do something with A and B ...

My guess is that complicated tree matching becomes easier when you
have these simpler tree matching constructs built into the language.

ObPython:  Pattern matching is the one ML thing I miss when I'm in Python..



	   - Amit