ignoring toplevel phrases?

ignoring toplevel phrases?

[Roland Zumkeller]

Hi,

Is it possible to modify the toplevel's behavior such that it silently
ignores any re-definitions of already bound identifiers (without
recompiling)? I would like to achieve the following:

# let x = 0;;
val x : int = 0
# let x = 1;;
# x;;
- : int = 0

The following code is supposed to replace all toplevel phrases by
"();;" during parsing (just as an experiment, it renders the toplevel
useless of course).

let original = !Toploop.parse_toplevel_phrase;;

Toploop.parse_toplevel_phrase :=
  fun _ -> original (Lexing.from_string ("();;"));;

After executing this, a non-terminating sequence is shown:
- : unit = ()
- : unit = ()
- : unit = ()
...

I'm probably not using the right hook. Any insight would be appreciated.

Best,

Roland

-- 
http://roland.zumkeller.googlepages.com/

Re: [Caml-list] ignoring toplevel phrases?

[Ashish Agarwal]

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Just curious, why do you want this?

On Fri, Jun 26, 2009 at 12:22 AM, Roland Zumkeller <
roland.zumkeller@gmail.com> wrote:

> Hi,
>
> Is it possible to modify the toplevel's behavior such that it silently
> ignores any re-definitions of already bound identifiers (without
> recompiling)? I would like to achieve the following:
>
> # let x = 0;;
> val x : int = 0
> # let x = 1;;
> # x;;
> - : int = 0
>
> The following code is supposed to replace all toplevel phrases by
> "();;" during parsing (just as an experiment, it renders the toplevel
> useless of course).
>
> let original = !Toploop.parse_toplevel_phrase;;
>
> Toploop.parse_toplevel_phrase :=
>  fun _ -> original (Lexing.from_string ("();;"));;
>
> After executing this, a non-terminating sequence is shown:
> - : unit = ()
> - : unit = ()
> - : unit = ()
> ...
>
> I'm probably not using the right hook. Any insight would be appreciated.
>
> Best,
>
> Roland
>
> --
> http://roland.zumkeller.googlepages.com/
>
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>

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Re: [Caml-list] ignoring toplevel phrases?

[Roland Zumkeller]

On Sat, Jun 27, 2009 at 12:44 AM, Ashish Agarwal<agarwal1975@gmail.com> wrote:
> Just curious, why do you want this?

I would like to save the state of the toplevel to the disk using
serialization. As functions can't be serialized one could check at
every "let" statement if there is a saved serialized value and if yes,
take that, otherwise execute the let-body. Just complinig is not an
option, since the *results* of previous computations should be saved,
i.e. 120 as opposed to "fact 5".

Re: [Caml-list] ignoring toplevel phrases?

[Richard Jones]

On Fri, Jun 26, 2009 at 11:22:16AM +0700, Roland Zumkeller wrote:
> Hi,
> 
> Is it possible to modify the toplevel's behavior such that it silently
> ignores any re-definitions of already bound identifiers (without
> recompiling)? I would like to achieve the following:
> 
> # let x = 0;;
> val x : int = 0
> # let x = 1;;
> # x;;
> - : int = 0

Have you considered a camlp4 extension?  I use a camlp4 extension in
Xavierbot to close some potential security holes in the toplevel, so
you could look at that code:

http://et.redhat.com/~rjones/xavierbot/

Rich.

-- 
Richard Jones
Red Hat