* [Caml-list] Random.self_init in Jane Street Core
@ 2014-05-21 12:10 Ollie Frolovs
2014-05-21 12:18 ` Dmitry Grebeniuk
2014-05-23 0:12 ` Nathan Mishra Linger
0 siblings, 2 replies; 9+ messages in thread
From: Ollie Frolovs @ 2014-05-21 12:10 UTC (permalink / raw)
To: caml users
Hello
I’ve been trying to use Random.self_init in Jane Street’s Core but every time I run my program it returns the same result as if the self_init is in fact completely deterministic. Two questions – what am I doing wrong and how do I make it “random” (as in returning different values on each run of the application).
I compile the following source into native code with “corebuild”.
When I run the program, the result is ALWAYS
1 0
1 1
0 1
0 2
0 3
I’ve also upload the code and the output from "opam list -i” on GitHub, if that’s more convenient https://gist.github.com/olliefr/d6312d8195e9a30aa80c
I believe I have the latest compiler/libraries. The system is OS X Mavericks.
Many thanks,
Ollie
--
(* SOURCE CODE BEGINS *)
open Core.Std
let _ = Random.self_init
(*
FIXME there must be something in the standard library to do this!
Iterate a function over a value, tail-recursively.
n: how many times
f: function to apply
a: initial value of the argument
*)
let rec iterate n f a =
if n<=0
then a
else iterate (n-1) f (f a)
(* Wandering Light *)
let light = (0,0)
let wander (x,y) =
match (1 + Random.int 4) with
1 -> (x+1, y)
| 2 -> (x, y+1)
| 3 -> (x-1, y)
| 4 -> (x, y+1)
| _ -> failwith "random direction is not 1 to 4, wtf?"
let render (x,y) = printf "%i %i\n" x y
let step light =
let newlight = wander light in
render newlight;
newlight
let _ = iterate 5 step (0,0)
(* THE END *)
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [Caml-list] Random.self_init in Jane Street Core
2014-05-21 12:10 [Caml-list] Random.self_init in Jane Street Core Ollie Frolovs
@ 2014-05-21 12:18 ` Dmitry Grebeniuk
2014-05-21 12:25 ` Ollie Frolovs
2014-05-23 0:12 ` Nathan Mishra Linger
1 sibling, 1 reply; 9+ messages in thread
From: Dmitry Grebeniuk @ 2014-05-21 12:18 UTC (permalink / raw)
To: Ollie Frolovs; +Cc: caml users
Hello.
> let _ = Random.self_init
That's why I almost never use "let _ = ...", or
constrain "_" to some type when I use it.
Try to replace it with "let () = ..." and follow compiler
errors. Or with "let (_ : unit) = ...".
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [Caml-list] Random.self_init in Jane Street Core
2014-05-21 12:18 ` Dmitry Grebeniuk
@ 2014-05-21 12:25 ` Ollie Frolovs
2014-05-21 12:28 ` David House
0 siblings, 1 reply; 9+ messages in thread
From: Ollie Frolovs @ 2014-05-21 12:25 UTC (permalink / raw)
To: caml users
oh dear! i think i know what happened. self_init has never been called in the first place! it requires a unit argument which i did not give it, so the “alias” to Random.self_init was assigned to nothing, so to speak, instead of calling the function.
Many thanks, Dmitry! I’ve amended that line to let () = Random.self_init () and it works.
On 21 May 2014, at 13:18, Dmitry Grebeniuk <gdsfh1@gmail.com> wrote:
> Hello.
>
>> let _ = Random.self_init
>
> That's why I almost never use "let _ = ...", or
> constrain "_" to some type when I use it.
> Try to replace it with "let () = ..." and follow compiler
> errors. Or with "let (_ : unit) = ...".
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [Caml-list] Random.self_init in Jane Street Core
2014-05-21 12:25 ` Ollie Frolovs
@ 2014-05-21 12:28 ` David House
2014-05-21 16:40 ` Martin Jambon
0 siblings, 1 reply; 9+ messages in thread
From: David House @ 2014-05-21 12:28 UTC (permalink / raw)
To: Ollie Frolovs; +Cc: caml users
[-- Attachment #1: Type: text/plain, Size: 1363 bytes --]
Relatedly, one should be careful using the [ignore] function. Always give
its argument a type signature. E.g. if you do this:
ignore (my_function foo);
Then this will start silently not calling [my_function] whenever someone
adds a second argument. You should instead use:
ignore (my_function foo : Foo.t);
On 21 May 2014 13:25, Ollie Frolovs <ollie.frolovs.2012@my.bristol.ac.uk>wrote:
> oh dear! i think i know what happened. self_init has never been called in
> the first place! it requires a unit argument which i did not give it, so
> the “alias” to Random.self_init was assigned to nothing, so to speak,
> instead of calling the function.
>
> Many thanks, Dmitry! I’ve amended that line to let () = Random.self_init
> () and it works.
>
> On 21 May 2014, at 13:18, Dmitry Grebeniuk <gdsfh1@gmail.com> wrote:
>
> > Hello.
> >
> >> let _ = Random.self_init
> >
> > That's why I almost never use "let _ = ...", or
> > constrain "_" to some type when I use it.
> > Try to replace it with "let () = ..." and follow compiler
> > errors. Or with "let (_ : unit) = ...".
>
>
> --
> Caml-list mailing list. Subscription management and archives:
> https://sympa.inria.fr/sympa/arc/caml-list
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs
>
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^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [Caml-list] Random.self_init in Jane Street Core
2014-05-21 12:28 ` David House
@ 2014-05-21 16:40 ` Martin Jambon
2014-05-22 9:01 ` Ben Millwood
0 siblings, 1 reply; 9+ messages in thread
From: Martin Jambon @ 2014-05-21 16:40 UTC (permalink / raw)
To: David House; +Cc: caml users, Ollie Frolovs
On Wed 21 May 2014 05:28:00 AM PDT, David House wrote:
> Relatedly, one should be careful using the [ignore] function. Always
> give its argument a type signature. E.g. if you do this:
>
> ignore (my_function foo);
>
> Then this will start silently not calling [my_function] whenever
> someone adds a second argument. You should instead use:
>
> ignore (my_function foo : Foo.t);
I think it used to be a problem but it no longer is. Recent versions of
OCaml give a warning when passing a function, so there's no need for a
type annotation:
$ ocaml
OCaml version 4.01.0
# ignore print_endline;;
Warning 5: this function application is partial,
maybe some arguments are missing.
- : unit = ()
>
> On 21 May 2014 13:25, Ollie Frolovs
> <ollie.frolovs.2012@my.bristol.ac.uk
> <mailto:ollie.frolovs.2012@my.bristol.ac.uk>> wrote:
>
> oh dear! i think i know what happened. self_init has never been
> called in the first place! it requires a unit argument which i did
> not give it, so the “alias” to Random.self_init was assigned to
> nothing, so to speak, instead of calling the function.
>
> Many thanks, Dmitry! I’ve amended that line to let () =
> Random.self_init () and it works.
>
> On 21 May 2014, at 13:18, Dmitry Grebeniuk <gdsfh1@gmail.com
> <mailto:gdsfh1@gmail.com>> wrote:
>
> > Hello.
> >
> >> let _ = Random.self_init
> >
> > That's why I almost never use "let _ = ...", or
> > constrain "_" to some type when I use it.
> > Try to replace it with "let () = ..." and follow compiler
> > errors. Or with "let (_ : unit) = ...".
>
>
> --
> Caml-list mailing list. Subscription management and archives:
> https://sympa.inria.fr/sympa/arc/caml-list
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs
>
>
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [Caml-list] Random.self_init in Jane Street Core
2014-05-21 16:40 ` Martin Jambon
@ 2014-05-22 9:01 ` Ben Millwood
2014-05-22 17:22 ` Martin Jambon
0 siblings, 1 reply; 9+ messages in thread
From: Ben Millwood @ 2014-05-22 9:01 UTC (permalink / raw)
To: Martin Jambon; +Cc: David House, caml users, Ollie Frolovs
[-- Attachment #1: Type: text/plain, Size: 2729 bytes --]
On 21 May 2014 17:40, Martin Jambon <martin.jambon@ens-lyon.org> wrote:
> On Wed 21 May 2014 05:28:00 AM PDT, David House wrote:
>
>> Relatedly, one should be careful using the [ignore] function. Always
>> give its argument a type signature. E.g. if you do this:
>>
>> ignore (my_function foo);
>>
>> Then this will start silently not calling [my_function] whenever
>> someone adds a second argument. You should instead use:
>>
>> ignore (my_function foo : Foo.t);
>>
>
> I think it used to be a problem but it no longer is. Recent versions of
> OCaml give a warning when passing a function, so there's no need for a type
> annotation:
>
> $ ocaml
> OCaml version 4.01.0
>
> # ignore print_endline;;
> Warning 5: this function application is partial,
> maybe some arguments are missing.
> - : unit = ()
>
You're right that this warning exists and mitigates the problem somewhat,
but it doesn't save you from the scenario where, say, a function changes
from returning unit and throwing exceptions in the case of error to
returning some error value, or vice versa. It seems just generally if the
return type of a function you use changes that's probably something you'd
want noise made about.
>> On 21 May 2014 13:25, Ollie Frolovs
>> <ollie.frolovs.2012@my.bristol.ac.uk
>> <mailto:ollie.frolovs.2012@my.bristol.ac.uk>> wrote:
>>
>> oh dear! i think i know what happened. self_init has never been
>> called in the first place! it requires a unit argument which i did
>> not give it, so the “alias” to Random.self_init was assigned to
>> nothing, so to speak, instead of calling the function.
>>
>> Many thanks, Dmitry! I’ve amended that line to let () =
>> Random.self_init () and it works.
>>
>> On 21 May 2014, at 13:18, Dmitry Grebeniuk <gdsfh1@gmail.com
>> <mailto:gdsfh1@gmail.com>> wrote:
>>
>> > Hello.
>> >
>> >> let _ = Random.self_init
>> >
>> > That's why I almost never use "let _ = ...", or
>> > constrain "_" to some type when I use it.
>> > Try to replace it with "let () = ..." and follow compiler
>> > errors. Or with "let (_ : unit) = ...".
>>
>>
>> --
>> Caml-list mailing list. Subscription management and archives:
>> https://sympa.inria.fr/sympa/arc/caml-list
>> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
>> Bug reports: http://caml.inria.fr/bin/caml-bugs
>>
>>
>>
>
>
> --
> Caml-list mailing list. Subscription management and archives:
> https://sympa.inria.fr/sympa/arc/caml-list
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs
>
[-- Attachment #2: Type: text/html, Size: 4531 bytes --]
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [Caml-list] Random.self_init in Jane Street Core
2014-05-22 9:01 ` Ben Millwood
@ 2014-05-22 17:22 ` Martin Jambon
0 siblings, 0 replies; 9+ messages in thread
From: Martin Jambon @ 2014-05-22 17:22 UTC (permalink / raw)
To: Ben Millwood; +Cc: David House, caml users, Ollie Frolovs
On Thu 22 May 2014 02:01:01 AM PDT, Ben Millwood wrote:
> On 21 May 2014 17:40, Martin Jambon <martin.jambon@ens-lyon.org
> <mailto:martin.jambon@ens-lyon.org>> wrote:
>
> On Wed 21 May 2014 05:28:00 AM PDT, David House wrote:
>
> Relatedly, one should be careful using the [ignore] function.
> Always
> give its argument a type signature. E.g. if you do this:
>
> ignore (my_function foo);
>
> Then this will start silently not calling [my_function] whenever
> someone adds a second argument. You should instead use:
>
> ignore (my_function foo : Foo.t);
>
>
> I think it used to be a problem but it no longer is. Recent
> versions of OCaml give a warning when passing a function, so
> there's no need for a type annotation:
>
> $ ocaml
> OCaml version 4.01.0
>
> # ignore print_endline;;
> Warning 5: this function application is partial,
> maybe some arguments are missing.
> - : unit = ()
>
>
> You're right that this warning exists and mitigates the problem
> somewhat, but it doesn't save you from the scenario where, say, a
> function changes from returning unit and throwing exceptions in the
> case of error to returning some error value, or vice versa. It seems
> just generally if the return type of a function you use changes that's
> probably something you'd want noise made about.
I can see it's a problem when the function that throws an exception
does not return unit. However if the original function returns unit, we
don't use ignore in the first place and we get a warning if the return
type changes. If the original function returns something but then
switches to unit + exception, I guess the compiler could warn against
that too:
Warning X: this 'ignore' is useless
> On 21 May 2014 13:25, Ollie Frolovs
> <ollie.frolovs.2012@my.__bristol.ac.uk
> <mailto:ollie.frolovs.2012@my.bristol.ac.uk>
> <mailto:ollie.frolovs.2012@my.__bristol.ac.uk
> <mailto:ollie.frolovs.2012@my.bristol.ac.uk>>> wrote:
>
> oh dear! i think i know what happened. self_init has never
> been
> called in the first place! it requires a unit argument
> which i did
> not give it, so the “alias” to Random.self_init was
> assigned to
> nothing, so to speak, instead of calling the function.
>
> Many thanks, Dmitry! I’ve amended that line to let () =
> Random.self_init () and it works.
>
> On 21 May 2014, at 13:18, Dmitry Grebeniuk
> <gdsfh1@gmail.com <mailto:gdsfh1@gmail.com>
> <mailto:gdsfh1@gmail.com <mailto:gdsfh1@gmail.com>>> wrote:
>
> > Hello.
> >
> >> let _ = Random.self_init
> >
> > That's why I almost never use "let _ = ...", or
> > constrain "_" to some type when I use it.
> > Try to replace it with "let () = ..." and follow compiler
> > errors. Or with "let (_ : unit) = ...".
>
>
> --
> Caml-list mailing list. Subscription management and archives:
> https://sympa.inria.fr/sympa/__arc/caml-list
> <https://sympa.inria.fr/sympa/arc/caml-list>
> Beginner's list:
> http://groups.yahoo.com/group/__ocaml_beginners
> <http://groups.yahoo.com/group/ocaml_beginners>
> Bug reports: http://caml.inria.fr/bin/caml-__bugs
> <http://caml.inria.fr/bin/caml-bugs>
>
>
>
>
>
> --
> Caml-list mailing list. Subscription management and archives:
> https://sympa.inria.fr/sympa/__arc/caml-list
> <https://sympa.inria.fr/sympa/arc/caml-list>
> Beginner's list: http://groups.yahoo.com/group/__ocaml_beginners
> <http://groups.yahoo.com/group/ocaml_beginners>
> Bug reports: http://caml.inria.fr/bin/caml-__bugs
> <http://caml.inria.fr/bin/caml-bugs>
>
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [Caml-list] Random.self_init in Jane Street Core
2014-05-21 12:10 [Caml-list] Random.self_init in Jane Street Core Ollie Frolovs
2014-05-21 12:18 ` Dmitry Grebeniuk
@ 2014-05-23 0:12 ` Nathan Mishra Linger
2014-05-23 0:15 ` Nathan Mishra Linger
1 sibling, 1 reply; 9+ messages in thread
From: Nathan Mishra Linger @ 2014-05-23 0:12 UTC (permalink / raw)
To: Ollie Frolovs; +Cc: caml users
[-- Attachment #1: Type: text/plain, Size: 4265 bytes --]
I think the problem is that you aren't *calling* Random.self_init. To do so, change the line
let _ = Random.self_init
to
let () = Random.self_init ()
The value that _ is matching against in your program has type unit -> unit rather than just unit.
—
Sent from Mailbox
On Wed, May 21, 2014 at 8:12 AM, Ollie Frolovs
<ollie.frolovs.2012@my.bristol.ac.uk> wrote:
> Hello
> I’ve been trying to use Random.self_init in Jane Street’s Core but every time I run my program it returns the same result as if the self_init is in fact completely deterministic. Two questions – what am I doing wrong and how do I make it “random” (as in returning different values on each run of the application).
> I compile the following source into native code with “corebuild”.
> When I run the program, the result is ALWAYS
> 1 0
> 1 1
> 0 1
> 0 2
> 0 3
> I’ve also upload the code and the output from "opam list -i” on GitHub, if that’s more convenient https://gist.github.com/olliefr/d6312d8195e9a30aa80c
> I believe I have the latest compiler/libraries. The system is OS X Mavericks.
> Many thanks,
> Ollie
> --
> (* SOURCE CODE BEGINS *)
> open Core.Std
>
> let _ = Random.self_init
> (*
> FIXME there must be something in the standard library to do this!
>
> Iterate a function over a value, tail-recursively.
> n: how many times
> f: function to apply
> a: initial value of the argument
> *)
> let rec iterate n f a =
> if n<=0
> then a
> else iterate (n-1) f (f a)
> (* Wandering Light *)
> let light = (0,0)
> let wander (x,y) =
> match (1 + Random.int 4) with
> 1 -> (x+1, y)
> | 2 -> (x, y+1)
> | 3 -> (x-1, y)
> | 4 -> (x, y+1)
> | _ -> failwith "random direction is not 1 to 4, wtf?"
>
> let render (x,y) = printf "%i %i\n" x y
>
> let step light =
> let newlight = wander light in
> render newlight;
> newlight
>
> let _ = iterate 5 step (0,0)
> (* THE END *)
> --
> Caml-list mailing list. Subscription management and archives:
> https://sympa.inria.fr/sympa/arc/caml-list
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs
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^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [Caml-list] Random.self_init in Jane Street Core
2014-05-23 0:12 ` Nathan Mishra Linger
@ 2014-05-23 0:15 ` Nathan Mishra Linger
0 siblings, 0 replies; 9+ messages in thread
From: Nathan Mishra Linger @ 2014-05-23 0:15 UTC (permalink / raw)
To: Ollie Frolovs; +Cc: caml users
[-- Attachment #1: Type: text/plain, Size: 4446 bytes --]
Oops. Nevermind. —
Sent from Mailbox
On Thu, May 22, 2014 at 8:12 PM, Nathan Mishra Linger
<nathan.mishralinger@gmail.com> wrote:
> I think the problem is that you aren't *calling* Random.self_init. To do so, change the line
> let _ = Random.self_init
> to
> let () = Random.self_init ()
> The value that _ is matching against in your program has type unit -> unit rather than just unit.
> —
> Sent from Mailbox
> On Wed, May 21, 2014 at 8:12 AM, Ollie Frolovs
> <ollie.frolovs.2012@my.bristol.ac.uk> wrote:
>> Hello
>> I’ve been trying to use Random.self_init in Jane Street’s Core but every time I run my program it returns the same result as if the self_init is in fact completely deterministic. Two questions – what am I doing wrong and how do I make it “random” (as in returning different values on each run of the application).
>> I compile the following source into native code with “corebuild”.
>> When I run the program, the result is ALWAYS
>> 1 0
>> 1 1
>> 0 1
>> 0 2
>> 0 3
>> I’ve also upload the code and the output from "opam list -i” on GitHub, if that’s more convenient https://gist.github.com/olliefr/d6312d8195e9a30aa80c
>> I believe I have the latest compiler/libraries. The system is OS X Mavericks.
>> Many thanks,
>> Ollie
>> --
>> (* SOURCE CODE BEGINS *)
>> open Core.Std
>>
>> let _ = Random.self_init
>> (*
>> FIXME there must be something in the standard library to do this!
>>
>> Iterate a function over a value, tail-recursively.
>> n: how many times
>> f: function to apply
>> a: initial value of the argument
>> *)
>> let rec iterate n f a =
>> if n<=0
>> then a
>> else iterate (n-1) f (f a)
>> (* Wandering Light *)
>> let light = (0,0)
>> let wander (x,y) =
>> match (1 + Random.int 4) with
>> 1 -> (x+1, y)
>> | 2 -> (x, y+1)
>> | 3 -> (x-1, y)
>> | 4 -> (x, y+1)
>> | _ -> failwith "random direction is not 1 to 4, wtf?"
>>
>> let render (x,y) = printf "%i %i\n" x y
>>
>> let step light =
>> let newlight = wander light in
>> render newlight;
>> newlight
>>
>> let _ = iterate 5 step (0,0)
>> (* THE END *)
>> --
>> Caml-list mailing list. Subscription management and archives:
>> https://sympa.inria.fr/sympa/arc/caml-list
>> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
>> Bug reports: http://caml.inria.fr/bin/caml-bugs
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^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2014-05-23 0:15 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2014-05-21 12:10 [Caml-list] Random.self_init in Jane Street Core Ollie Frolovs
2014-05-21 12:18 ` Dmitry Grebeniuk
2014-05-21 12:25 ` Ollie Frolovs
2014-05-21 12:28 ` David House
2014-05-21 16:40 ` Martin Jambon
2014-05-22 9:01 ` Ben Millwood
2014-05-22 17:22 ` Martin Jambon
2014-05-23 0:12 ` Nathan Mishra Linger
2014-05-23 0:15 ` Nathan Mishra Linger
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