Very true, Tobias. I can't justify the complication to the language it would entail. There's no obvious simple way to do this – in/out-ness is a property partly of a binding and partly of a value. It's just kind of messy. Sure, it prevents some errors, but so does static type checking and we're giving that up for the sake of simplicity and productivity.
On Thu, Jun 12, 2014 at 5:33 PM, Tobias Knopp <tobias.kn...@googlemail.com> wrote: > Julia is a quite simple language and I really appreciate that it does not > have every feature out there in other languages. Const parameters from C++ > are certainly an interesting thing but in my experience they also slow down > my (personal) development time as I have to reason about yet another thing. > One also has to be very concentrated when reading const aware C++ code as > the human brain can only recognize a certain amount of chunks at a time. > > Am Donnerstag, 12. Juni 2014 22:58:47 UTC+2 schrieb vav...@uwaterloo.ca: > >> With respect to S. Karpinski's comment, I can understand completely that >> this kind of inarg/outarg housekeeping stuff that I propose is not a high >> priority for the developers of Julia at this early point of Julia's >> development. So in that case, let me suggest that the language allow these >> declarations right now purely as source-code documentation (i.e., they have >> no effect on the compilation/execution), but the Julia documentation can >> warn users that in future releases they may be enforced by the compiler. >> >> -- Steve Vavasis >> >> >> On Thursday, June 12, 2014 8:28:18 PM UTC+3, vav...@uwaterloo.ca wrote: >>> >>> Both C++ and Fortran 90 allow the programmer to annotate >>> call-by-reference arguments to a function as to whether the function is >>> allowed to change them (this is denoted const & in C++). The compiler >>> then enforces the const-ness of the argument. I don't see how to do this >>> in Julia. Is it available? If not, is there a reason why it was not >>> included? This is a fairly basic tool for self-documenting code and for >>> ensuring program correctness. >>> >>> And a related question: the documentation makes a big deal about "stable >>> types" for function return arguments. An obvious question is why the >>> language doesn't allow the programmer to declare in the function heading >>> what will be the return types of the function, and then have the compiler >>> enforce this stability. Is this possible in Julia? If not, is there a >>> technical reason for omitting it? >>> >>> Thanks, >>> Steve Vavasis >>> >>> P.S. I have a few more questions but I'll pause now to wait for answers >>> to these questions. I hope they are easy to answer! >>> >>
