]> From: Richard Jones <rich@annexia.org> > On Tue, Jul 15, 2003 at 10:04:36AM +0900, Jacques Garrigue wrote: > > By the way, there is a reason "let _ =" produces no warning: this is > > the only way to do a partial application without warning. > > "expr; ..." and even "ignore (expr); ..." will produce a warning. > > Interesting ... what's the use of a partial application which is > then ignored? The same as all application whose result is ignored: side effects. I know this is quite rare. (I can remember using this only once.) But it would be disturbing to make it completely impossible. Or is it not so important? Actually I wonder whether it would not be safer to simply warn for all unused partial applications in a compiled program. This is a bit subtle, as one has to keep track of unused variables too (functions defined by partial application which are never used). A middle ground would be to only warn when the wild pattern matches a function type, assuming that when you name something you know what you are doing. This would be mostly compatible: you just have to name the pattern when you want to discard a function. As a nice aside, it would avoid most uses of "ignore". By the way, my personal approach would be to let programers declare what they want: remove the "should be unit" warning (it can be easily enforced by "let () = ... in"), and remove all warnings on "ignore", since you could then write "let _ = ... in" if you want the partial application warning. But this is maybe expecting too much from programmers. Comments? Jacques Garrigue ------------------- 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