Re: Making sense of predicates

["Dan'l Miller" <optikos@verizon.net>]

On Tuesday, October 22, 2013 11:30:30 AM UTC-5, Dmitry A. Kazakov wrote:
> The goal should be a leaner and more powerful type system with the present
> type system implemented on top of it at the library level, 100% backward
> compatible.

Ahhhh, you seek effectively the C++ vision, but done differently somehow (or else why not simply leave Ada and program in C++2011).  Then, your primary task is not to convince people in Ada of matters related to the typing-system per se.  Rather your goal is to convince people in Ada how delegating language/compiler functionality upward to the "library level" would not suffer the disastrous defects plaguing C++'s metatemplate programming (MTP).  What you seek is not a better typing-system per se.  What you seek is a better way of layering the compiler and extending the compiler, such as multistage programming (of which C++-style MTP is a poor-man's misguided inferior-quality knock-off of a half-baked flight of fancy).  [Hint:  don't replicate the C++ MTP mess; do something *entirely* different than the C++ direction.]  You should advocate for what that multistage(-or-whatever) programming feature-set would look like in Ada-refounded, act like in Ada-refounded, enforce safety like in Ada-refounded, and so forth, preferably revealing both the new utopia as well as the impeccability of the Ada2012 backward-compatibility.  Then a feature-rich rethought typing-system is merely the first impressive tour-de-force demonstration of such compiler extensibility.

Btw, Seed7 has done some limited work in this direction, but is best thought of as a one-off tangential demonstration of some categories of partial-solutions toward this compiler-extensibility goal, instead of as the only path leading toward the promised land of multistage programming and compiler extensibility.  Of course, the set {OCaml, Camlp4, MetaOCaml} deserve a peek as well, borrowing here & there, leaving behind their bizarreness.

> P.S. Putting up such lists is a completely wasted time, as nothing will
> ever happen, until somebody with the influence of Ichbiah or Taft will nuke
> the swamp again.

Your pessimism here presumes that neither Tucker Taft nor anyone else of visionary influence reads comp.lang.ada, which I suspect is entirely false.  Hence, when good ideas are well-formed, they might inspire those on the ISO standardization committee (or at AdaCore & the like) to work on such goals.