Re: [Caml-list] equality operators in OCaml

[Vincent Hanquez <tab@snarc.org>]

On Thu, Jul 24, 2008 at 02:27:51PM -0500, Raj Bandyopadhyay wrote:
> Hi OCaml folk
>
> I apologize if I've been asking too many questions on this list  
> recently, but I'm working on a heavy OCaml application and need help  
> sometimes.
>
> I am having a disagreement with a colleague about how the equality  
> operators in OCaml work and am trying to resolve it conclusively.
>
> 1) I understand that the '==' operator is basically a pointer comparison  
> i.e. a==b true  iff a and b are the same entity. Is this true?

yes. only valid for object that are in blocks though (int, char are not).
for object not in block, you end up with a simple =

> 2) Where can I find the code implementing the '==' operator in the OCaml  
> code?

byterun/compare.c : caml_equal which call compare_val with total=0 (which
means to not compare inside blocks)

> 3) In case I do want to check object identity and can use the ==  
> operator, would it be faster to use '==', '=' or a match statement?

i believe == is the fastest one. but that's just based on how the thing
works compare to the others compare, not on empirical benchs.

-- 
Vincent