Re: [Caml-list] tail call optimization

[Dustin Sallings <dustin@spy.net>]

On Nov 18, 2003, at 22:50, Brian Hurt wrote:

> This function is not tail recursive.  Basically, if the recursive call
> either a) is wrapped in a try block, or b) has it's return value 
> modified
> in any way, the function isn't tail recursive.  Your function violates
> clause a, the following function violates clause b:
>
> let append a b =
> 	match a with
> 		| [] -> b
> 		| h :: t -> h :: (append t b)
> ;;

	I guess I don't understand the point of clause a.  The try block 
doesn't seem like it should prevent the optimization.

>> 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?).
>
> Stack overflows are a classic sign of a function you thought was tail
> recursive not being tail recursive.

	Yes, this file was my test for tail recursion.  :)

--
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pub  1024/3CAE01D5 1994/11/03 Dustin Sallings <dustin@spy.net>
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