On Fri, 7 Sep 2001, Jon Fairbairn wrote:
due to cache coherency issues.) In that context, there was an old suggestion of Don Knuth's that program source code should in the idealized future not just contain the final, optimized code (with perhaps the original code in comments) but as a kind of set of layers each representing the same semantic program but with increasing orders of optimisation, and links between `things' annotated with a label placed by the programmer explaining why the transformation between an unoptimised version `thing' and an optimised `thing'.
[snip]
I suspect that such a system is still at least 25 years away from feasiblity though :-(
That seems to me to be an overestimate.
You might be right; I just have nasty 5 year old memories (that my subconscious hasn't succeeded in suppressing :-) ) of trying to coax OBJ3 to perform proofs on very simple things and finding it so difficult that I can't imagine it being usable by a programmer with no intrinsic interest in the logic process without some extreme advances (which may just be increasing processor capacity so limited application of `brute force' approaches become more feasible). In some ways I suspect that Knuth's idea may be simpler to implement than yours in that there all the creativity and optimization is performed by the programmer; the computer just (very reliably) ensures equivalence between the two versions of the program and (with vague reliability) tries to alter the optimised program as small changes to the original are made to preserve semantics but not necessarily efficiency. But I'll certainly be keeping an eye out in the future for a system of either kind that I can use in my programming. ___cheers,_dave________________________________________________________ www.cs.bris.ac.uk/~tweed/pi.htm |tweed's law: however many computers email: tweed@cs.bris.ac.uk | you have, half your time is spent work tel: (0117) 954-5250 | waiting for compilations to finish.