Just a couple of caveats and notes:

 I’ve included the DLR source with my modification for the unary ’+’ operator.
 I haven’t included Antlr3 because I’ve got a version (3.1 beta) from around Jan 1st this year and I’m pretty sure it’s moved on since then. But the generated C# files are include in the project and so is the ANTLR3 C# runtime, so the project will run ’as -is’.
 the calculator is in Test, and uses the Antlr3 lexer/parser/tree generator to parse simple expressions like (3+4)*(4+5). If you run the program from within VS 2008, you should get a DLR console (three >>> prompts).

Finally, the CMA clause: the program & code is provided AS IS AND WITH NO WARRANTY OR GUARANTEE WHATSOEVER. If your PC catches fire, or whatever, that’s your problem.

Dermot