Hi, During the summer, I have been designing and implementing a metalanguage for C preprocessor metaprogramming named Order. The Order language is a *complete* high-level functional programming language with features such as - lexical scoping, - first-class functions, - anonymous functions, - partial application of functions (currying), - intuitive call-by-value semantics, and - tail-recursion optimization. The Order prelude supports, among other things, - arithmetic on arbitrary precision natural numbers and small literals {0,...,100}, - sequences (with many higher-order functions), - tuples, and - so called token strings/sequences. The Order interpreter, which is implemented using the C preprocessor macro mechanism, can be used to generate arbitrary sequences of preprocessing tokens (read: code). The intepreter also provides a debug mode that checks for many kinds of programming errors (syntax-errors, run-time type errors and user assertions). The Order language has been designed to transform the feel of C preprocessor metaprogramming from "learning lots of tricky, low-level Cpp specific idioms" to "thinking in an intuitive high-level language". Here is a short example of Order code that generates the complete lyrics to the song "99 Bottles of Beer on the Wall": #define GEN_phrase(N_bottles, N_minus_1_bottles) \ N_bottles of beer on the wall, \ N_bottles of beer, take one down, pass it around, \ N_minus_1_bottles of beer on the wall. #define ORDER_PP_DEF_8bottles \ ORDER_PP_FN(8fn(8N, \ 8cond((8greater(8N, 1), \ 8separate(8N, 8quote(bottles))) \ (8equal(8N, 1), \ 8quote(1 bottle)) \ (8else, \ 8quote(no more bottles))))) ORDER_PP(8for_each_in_range (8fn(8N, 8emit(8quote(GEN_phrase), 8tuple(8bottles(8N), 8bottles(8dec(8N))))), 100, 1)) (The above is an extract from a completely documented example.) There are two known caveats. First of all, the Order interpreter requires standard C variadic macros and placemarkers, which aren't standard C++, yet. The second caveat is that the Order interpreter currently requires a standards conforming preprocessor. The interpreter has been developed on the GNU CPP (3.x). Theoretically, the interpreter should be quite portable to less conforming preprocessors, because the interpreter is a "closed system of macros", but I personally don't have the preprocessors nor the time, though I would be happy to assist in such porting work by providing information on the interpreter. I'm currently working on the Order programming manual. I have already written several completely documented examples for the programming manual, which should be enough to get one started in using the Order interpreter, but one example I'd like to have would be a state machine compiler (SMC). Instead of implementing and documenting a SMC myself, I'd like to challenge *you* to write such a SMC example to be included in the forthcoming manual. Knowing that the documentation is still unfinished, I will be happy to assist people writing such a compiler (or some other kind of code generator) through e-mail (I might setup a mailing list). This might also help me to identify specific issues (e.g. sources of confusion, important design heuristics) that need to be addressed in the forthcoming programming manual. If you are interested in seeing the future of C preprocessor metaprogramming by trying out the Order intepreter and implement a state machine compiler (or some other program generator), please contact me at vesa_karvonen@hotmail.com. Note that you won't need previous Boost.Preprocessr library experience. Learning to use the Order interpreter should be an order of magnitude easier than learning to use the Boost.Preprecessor library. After I've completed the Order programming manual, I will release the Order interpreter (independently) and submit it to Boost if there is enough interest. Regards, Vesa Karvonen _________________________________________________________________ STOP MORE SPAM with the new MSN 8 and get 2 months FREE* http://join.msn.com/?page=features/junkmail