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[Caml-list] Constructors as functions and tuples in constructors
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Date: -- (:)
From: Michal Moskal <malekith@p...>
Subject: Re: [Caml-list] Constructors as functions and tuples in constructors
On Wed, Oct 08, 2003 at 07:57:03PM +0400, Serge wrote:
> 
> Gentlemen!

Well, maybe there are some ladies here? :-)

[...]

> Second, it would also be nice not to have "the concept of constructor
> arity", and treat the code below as correct:
> 
> type t = A of int * int
> let _ = 
>   match A (17, 0) with
>     A z -> match z with (x, y) -> ()

Just need to use () after "of", like this:

# type t = A of (int * int);;
type t = A of (int * int)
# let _ = match A (17, 0) with A z -> z;;
- : int * int = (17, 0)
# 

However constructing A of int * int takes one allocation (it's
<tag_of_a> <int> <int>), while A of (int * int) -- two (it's <tag_of_a>
<ptr_to_int_int>). Referencing it also takes one indirection more.

-- 
: Michal Moskal :: http://www.kernel.pl/~malekith : GCS {C,UL}++++$ a? !tv
: When in doubt, use brute force. -- Ken Thompson : {E-,w}-- {b++,e}>+++ h

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