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Ques from a beginner: how to access a type defined in one .ml file in another .ml file
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Date: 2010-05-12 (10:30)
From: Tarun Sethi <tarunsethi01@g...>
Subject: Ques from a beginner: how to access a type defined in one .ml file in another .ml file

I m very new to ocaml and I am not sure if this the right forum to ask a
beginner level question. I have tried reading tutorials and the manual but
no help. Please help me on the problem below,

In a.ml a record type t is defined and is also defined transparently
in a.mli, i.e. in d interface so that the type definition is available
to all other files.

a.ml also has a function, func, which returns a list of t.

Now in another file, b.ml  i m calling func, now obviously ocaml
compiler wud nt be able to infer d type of objects stored in d list,
for compiler its just a list. so in b.ml, i hav something like dis,

let tlist = A.func in
let vart = List.hd tlist in
printf "%s\n" vart.name     (*name is a field in record t*)

Now here i get a compiler error sayin "Unbound record field label
name" which makes sense as compiler can't infer d type of vart.

my first question: how do I explicitly provide d type of vart as t
                         i tried doing "let vart:A.t =  " but got the
same error.

I also tried creating another function to fetch the first element of d
list and mentioning return type as A.t, but then i got the "Unbound
value A.t". I did this:

let firstt = function
     [] -> 0
   | x :: _ -> A.t x ;;

The problem is compiler is unable to recognize A.t (a type) in b.ml
but is able to recognize function A.func. If I remove A.t from the
b.ml, i don'get any compiler errors.

Please help, its urgent work.
Thanks in advance!