Re: [Caml-list] Re: Toplevel function question

[Cedric Auger <Cedric.Auger@lri.fr>]

Joel Christner a écrit :
> Simpler representation - tried compiling this and got the same syntax 
> error - at a line number that was after the EOF.  Thanks in advance 
> for any help!!
>
> let add_text variablelist text =
>   variablelist.contents <- text::variablelist.contents
>
> let originalprogramcontents = ref [""]
>
> let _ =
>   let lexbuf = Lexing.from_channel stdin in
>   let rec storeoriginalprogram =
>     let expr = lexbuf in
>     match expr with
>     | EOF   -> ()
>     | _     -> (add_text originalprogramcontents expr); 
> storeoriginalprogram
>   in let parseprogram = List.iter
>     (fun n -> print_string n; print_string "\n";) originalprogramcontents
>
> $ ocamlc -c toplevel.ml <http://toplevel.ml>
> File "toplevel.ml <http://toplevel.ml>", line 17, characters 1-1:
> Syntax error
>
Why do you use ( and ) delimiting "add_text originalprogramcontents expr"?
in (fun n -> print_string n; print_string "\n";), last ";" is useless
as Benjamin said your "let" is missing its "in"
eventually I assume you didn't intended to write "expr = lexbuf", but 
rather "expr = parse lexbuf", where parse is a function you must define, 
probably the "Parser.expr Scanner.token" of your first mail, so I think 
that the following would be better:

let add_text variablelist text =
  variablelist := text::!variablelist

let originalprogramcontents = ref [""]

let _ =
  let lexbuf = Lexing.from_channel stdin in
  let rec storeoriginalprogram =
    let expr = Parser.expr Scanner.token lexbuf in
    match expr with
    | EOF   -> ()
    | _     -> add_text originalprogramcontents expr; storeoriginalprogram
  in
  List.iter
     (fun n -> print_string n; print_string "\n")
     originalprogramcontents

And I don't think "let _ =" is mandatory
Note that a list can be empty and you can write
let originalprogramcontents = ref []
if you want an empty list at beginning (I don't know if you need an 
empty list or a list containing an empty string), caml will guess its 
type since you used add_text on this list.
If you don't use the list or want to restrict a type you also can "cast" it:
let (originalprogramcontents : (string list) ref) = ref []


>    
>
>
> On Wed, May 13, 2009 at 4:43 PM, Joel Christner 
> <joel.christner@gmail.com <mailto:joel.christner@gmail.com>> wrote:
>
>     Hello,
>
>     I hope you guys don't mind another beginner's question, I'm
>     waiting on approval from the Yahoo! group moderator for the
>     beginner's section.
>
>     I'm trying to implement a toplevel function that will accept input
>     from stdin (someone running the program will do ./programname <
>     someinputfile), store it to a ref string list, and then once
>     stored, iteratively evaluate each item in the list individually.
>
>     What I've put together is:
>
>     let _ =
>       let lexbuf = Lexing.from_channel stdin in
>       let rec storeoriginalprogram =
>         let expr = Parser.expr Scanner.token lexbuf in
>         match expr with
>         | EOF   -> ()
>         | _     -> add_text originalprogramcontents expr;
>     storeoriginalprogram
>       in let parseprogram = List.iter
>         (fun n -> eval expr) originalprogramcontents
>
>     where...
>     - Parser and Scanner are already built and working great
>     - When a line of text comes in, it calls 'add_text' which adds the
>     expr into the 'originalprogramcontents' ref string list, and then
>     recursively calls itself to get the next line
>        - let originalprogramcontents = ref [""]
>        - let add_text variablelist text = variablelist.contents <-
>     text::variablelist.contents
>     - Then when finished reading from stdin, iteratively executes
>     'eval' against each line in the ref string list called
>     'originalprogramcontents'
>
>     For some reason (probably a stupid mistake on my part) it's giving
>     me a syntax error and pointing to a line of code that is AFTER the
>     end of my program:
>
>     $ make
>     ocamlc -c program.ml <http://program.ml>
>     File "program.ml <http://program.ml>", line 203, characters 2-2:
>     Syntax error
>     make: *** [program.cmo] Error 2
>
>     But my program is only 202 lines long.
>
>     Any ideas on how I might go about making this work?
>
>     Thanks
>     Joel
>
>
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>
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-- 
Cédric AUGER

Univ Paris-Sud, Laboratoire LRI, UMR 8623, F-91405, Orsay