Browse thread
Re: [Caml-list] Pattern matcher no more supposed to warn on non
- Luc Maranget
[
Home
]
[ Index:
by date
|
by threads
]
[ Message by date: previous | next ] [ Message in thread: previous | next ] [ Thread: previous | next ]
[ Message by date: previous | next ] [ Message in thread: previous | next ] [ Thread: previous | next ]
| Date: | -- (:) |
| From: | Luc Maranget <luc.maranget@i...> |
| Subject: | Re: [Caml-list] Pattern matcher no more supposed to warn on non |
>
>
> So long as the issue of when clauses has come up,
Well I am thinking about it, others complain loudly.
> I'll also point out that
> the pattern-compiler essentially assumes that when clauses are pure. I'm
> not complaining because I consider it poor style to violate this assumption,
You bet.
> but I've never heard it discussed anywhere.
> For the program below, ocamlopt version 3.00 produces a program that prints
> 1314.
>
> --Dan
>
> --
> | Dan Grossman www.cs.cornell.edu/home/danieljg H:607 256 0724 |
> | 5157 Upson Hall danieljg@cs.cornell.edu O:607 255 9834 |
Argl....
Dear Dan, which result would you consider to be correct ?
(1111 ?)
Please tell me...
(Note that I see no consitency either in 3.02 or 3.00,)
Cheers, thanks, and argl again !
--Luc
It is worth a warning in the manual, at least...
>
> ===============
>
> type y = {mutable c:bool}
> type x = {a:y; b:y}
>
> let f1 (v:x) =
> match v with
> {a = _; b = _} when (v.a.c <- false; v.b.c <- false; false) -> 0
> | {a = {c=false}; b = {c=false}} -> 1
> | {a = {c=false}; b = {c=true}} -> 2
> | {a = {c=true}; b = {c=false}} -> 3
> | {a = {c=true}; b = {c=true}} -> 4
>
> let f2 (v:x) =
> match v with
> {a = {c=true}; b = _} when (v.a.c <- false; v.b.c <- false; false) -> 0
> | {a = {c=false}; b = {c=false}} -> 1
> | {a = {c=false}; b = {c=true}} -> 2
> | {a = {c=true}; b = {c=false}} -> 3
> | {a = {c=true}; b = {c=true}} -> 4
>
> let f3 (v:x) =
> match v with
> {a = _; b = {c=true}} when (v.a.c <- false; v.b.c <- false; false) -> 0
> | {a = {c=false}; b = {c=false}} -> 1
> | {a = {c=false}; b = {c=true}} -> 2
> | {a = {c=true}; b = {c=false}} -> 3
> | {a = {c=true}; b = {c=true}} -> 4
>
> let f4 (v:x) =
> match v with
> {a = {c=true}; b={c=true}} when (v.a.c <- false; v.b.c <- false; false)
> -> 0
> | {a = {c=false}; b = {c=false}} -> 1
> | {a = {c=false}; b = {c=true}} -> 2
> | {a = {c=true}; b = {c=false}} -> 3
> | {a = {c=true}; b = {c=true}} -> 4
>
> let main () =
> let v1:x = {a = {c=true}; b = {c=true}} in
> let v2:x = {a = {c=true}; b = {c=true}} in
> let v3:x = {a = {c=true}; b = {c=true}} in
> let v4:x = {a = {c=true}; b = {c=true}} in
> print_int (f1 v1);
> print_int (f2 v2);
> print_int (f3 v3);
> print_int (f4 v4)
>
> let _ = main ()
> -------------------
> Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/
> 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/
To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr