]> Ok as there were the two same comments on my post I do a single answer. Here my first post: >> What about defining type that are subranges of int ? >> à la ADA... Here the comments: ----- >Then how do you make sure that the result of an arithmetic expression is >still within that sub-range? For example, m.( i + j ) ? > >Cheers, >Hao-yang Wang ----- >as i said to john skaller, won't you then get index incrementation exceptions ? >anyway, it's a trade-off. > >-- >Berke >mayur_naik@my-deja.com writes: ----- Now, as I am not an ADA guru I just show you my source: http://groups.google.com/groups?hl=fr&lr=&ie=UTF-8&oe=UTF-8&frame=right&th=5c68b368acf1e99&seekm=00-04-194%40comp.compilers#link5 ------------- BEGIN OF FOLLOWUP ------------- > Does any language or any machine provide some mechanism to: > > 1. index an array without checking its bounds > 2. throw an exception if the index was actually out of range > 3. allow the programmer to catch and handle the exception rather than > terminate the program Well, Ada does. The strong typing gives information to the compiler for it to deduce when range checking is not needed: declare subtype Index is Integer range 1..10; type Arr is array (Index) of Integer; a : Arr; element : Integer; j : Index := 1; k : Integer := 11; begin for i in a'Range loop element := a(i); -- no range checking needed, i is in range by definition end loop; a(j); -- range checking not needed, j is within Index by definition a(k); -- range checking needed due possibility of k being outside of Index exception when Constraint_Error => -- process the out-of-range error from a(k) end; -- Cheers, The Rhythm is around me, The Rhythm has control. Ray Blaak The Rhythm is inside me, blaak@infomatch.com The Rhythm has my soul. ------------- END OF FOLLOWUP ------------- IMHO, the use of subtypes help to avoid a lot of bound check, maybe not all of them, but I do not think that eliminating *all* the bounds check is useful. Another point is that using subranges you're not allowed to do many errors as when you are using bare int. Ciao Jo ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners