beginners list

beginners list

[christian konrad]

Hello again,

I just signed up to the beginners with the message: "/Your membership to 
the ocaml_beginners mailing list is waiting for the moderator's approval."
/so for a last time I misuse this list, sorry. I wrote this piece of code:

type ergebnis = {teamid1: int; teamid2: int; goals1: int; goals2: int};;
type spieltag = {number: int; ergebnisse: ergebnis list};;

...

let rec readSpieltagelist filehandle numberofgames =
    let createErgebnis tid1 tid2 g1 g2 =
        {teamid1=tid1; teamid2=tid2; goals1=g1; goals2=g2;}
    in
    let rec readErgebnisse fh number =
        match number with
        | 0 -> []
        | n -> let line = (input_line fh) in (Scanf.sscanf line 
"%d\t%d\t%d\t%d" createErgebnis):: (readErgebnisse fh (number-1));
    in
    try
        let spieltag = int_of_string(read_line filehandle) in
        let ergebnislist = (readErgebnisse filehandle numberofgames) in
        {number=spieltag; ergebnisse=ergebnislist;} :: 
(readSpieltagelist filehandle numberofgames);   
    with End_of_file -> [];;

with the hope to read from a file informations like:
1
1   2   3   4
3   2   1   6
4   2   1   9
2
1   4   9   2
3   2   1   9
9   1   2   3
3
...

I would call: readSpieltagelist filehandle 3
in that case.
This code doesn't compile, I get an error with the variable filehandle 
in this expression:

        let ergebnislist = (readErgebnisse filehandle numberofgames) in

"This expression has type unit but is here used with type in_channel"


Why that?? I really do not understand that. Do I use "filehandle" 
somewhere as a unit type? Where, why?


Thanks for help,
chris
//

Re: [Caml-list] beginners list

[Richard Jones]

On Sat, Feb 24, 2007 at 01:43:31PM -0500, christian konrad wrote:
> Hello again,
> 
> I just signed up to the beginners with the message: "/Your membership to 
> the ocaml_beginners mailing list is waiting for the moderator's approval."
> /so for a last time I misuse this list, sorry. I wrote this piece of code:

Christian, I've approved you for the beginners list now.

Rich.

-- 
Richard Jones
Red Hat UK Limited

Re: [Caml-list] beginners list

[micha]

christian konrad wrote:
> Hello again,
>
>
> Why that?? I really do not understand that. Do I use "filehandle" 
> somewhere as a unit type? Where, why?
>
read_line reads from stdin and expects type unit as parameter (you want 
to use input_line)

Michael

Re: [Caml-list] beginners list

[Jon Harrop]

On Saturday 24 February 2007 18:43, christian konrad wrote:
> (Scanf.sscanf line "%d\t%d\t%d\t%d" createErgebnis) ::
> (readErgebnisse fh (number-1)); 

I think you've made exactly the same mistake here. Also, the outer brackets 
are superfluous. You probably want:

  let line = Scanf.sscanf line "%d\t%d\t%d\t%d" createErgebnis in
  line :: readErgebnisse fh (number-1)

but it depends whether you wanted to recurse first or read a line first (I 
can't tell from your code and neither can the compiler).

-- 
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
OCaml for Scientists
http://www.ffconsultancy.com/products/ocaml_for_scientists