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To: Caml Mailing List <caml-list@inria.fr>
From: Dustin Sallings <dustin@spy.net>
Subject: [Caml-list] tail call optimization
Date: Tue, 18 Nov 2003 21:24:00 -0800
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	I read something on the list about how a function may be tail 
recursive, but not be compiled with tail call optimization.  What kinds 
of things might cause this?

	Specifically, I've got an ``iter_lines'' function I'd like to turn 
into a ``fold_lines'' function that looks something like this (a few 
different functions for different things):

let rec fold_lines f init_value ch =
     try
         let v = f (input_line ch) init_value in
         fold_lines f v ch
     with End_of_file -> init_value;
;;

	So, I have these other two functions:

let operate_on_file f fn =
     let ch = open_in fn in
     try
         let rv = f ch in
         close_in ch;
         rv
     with x ->
         close_in ch;
         raise x
;;

let fold_file_lines f init_value fn =
     operate_on_file (fold_lines f init_value) fn
;;

	I now want to count the lines in a file:

dustinti:~/prog/eprojects/snippets/ocaml/lib 586% wc -l numbers
  4769526 numbers
# Fileutils.fold_file_lines (fun x y -> y + 1) 0 "numbers";;
Stack overflow during evaluation (looping recursion?).

	Am I doing something wrong?

--
SPY                      My girlfriend asked me which one I like better.
pub  1024/3CAE01D5 1994/11/03 Dustin Sallings <dustin@spy.net>
|    Key fingerprint =  87 02 57 08 02 D0 DA D6  C8 0F 3E 65 51 98 D8 BE
L_______________________ I hope the answer won't upset her. ____________

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