[Caml-list] Facing syntax error.

[Caml-list] Facing syntax error.

[Bhavik Gandhi (hotmail)]

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Hi friends,
 
I am a novice to the OCAML language. I am trying to write a small
program and I am facing with a syntax error, any help will be
appreciated
 
let rec undup lst = try match lst with
  |[]->[]
  |h::tail -> match tail with
  |[]->[]
  |h::xt -> if (h=List.hd xt) then h::undup xt
  else raise(Failure "ERROR-Your list does not contain duplicates");;
 
Error: line 6, characters 67-69
Syntax error.
 
 
Bhavik Gandhi

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Re: [Caml-list] Facing syntax error.

[Matt Gushee]

On Tue, Oct 14, 2003 at 06:49:11PM -0800, Bhavik Gandhi (hotmail) wrote:
>  
> I am a novice to the OCAML language. I am trying to write a small
> program and I am facing with a syntax error, any help will be
> appreciated
>  
> let rec undup lst = try match lst with
>   |[]->[]
>   |h::tail -> match tail with
>   |[]->[]
>   |h::xt -> if (h=List.hd xt) then h::undup xt
>   else raise(Failure "ERROR-Your list does not contain duplicates");;
>  
> Error: line 6, characters 67-69
> Syntax error.

Right, because you have 'try' without 'with'. The syntax is

  try
    <desired operations>
  with
    <exception pattern> ->
      <exception handling code>
    | <exception pattern> -> (* 2nd & further patterns are optional *)
      <exception handling code>
    
You could make the above example work by adding a 'with' clause at the
end, e.g.

  with Failure ->
    print_endline "Exception handled.";
    []   (* exception handler must return same type as main operation *)

But that would actually be a little pointless in this case, since as far
as I can tell the only possible exception is the Failure raised by your
code. So without knowing your objectives in more detail, I would say the
most sensible approach would be to simply delete 'try' from this
function, and perhaps have a complete try-with block in some other
function that is calling this one.


-- 
Matt Gushee                 When a nation follows the Way,
Englewood, Colorado, USA    Horses bear manure through
mgushee@havenrock.com           its fields;
http://www.havenrock.com/   When a nation ignores the Way,
                            Horses bear soldiers through
                                its streets.
                                
                            --Lao Tzu (Peter Merel, trans.)

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Re: [Caml-list] Facing syntax error.

[Stefano Zacchiroli]

On Tue, Oct 14, 2003 at 06:49:11PM -0800, Bhavik Gandhi (hotmail) wrote:
> I am a novice to the OCAML language. I am trying to write a small
> program and I am facing with a syntax error, any help will be
> appreciated

Please use the beginners list for this kind of questions:

  http://groups.yahoo.com/group/ocaml_beginners

Cheers.

-- 
Stefano Zacchiroli  --  Master in Computer Science @ Uni. Bologna, Italy
zack@{cs.unibo.it,debian.org,bononia.it}  -  http://www.bononia.it/zack/
"  I know you believe you understood what you think I said, but I am not
sure you realize that what you heard is not what I meant!  " -- G.Romney

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