From: Diego Olivier Fernandez Pons <Diego.FERNANDEZ_PONS@etu.upmc.fr>
To: Jacques Garrigue <garrigue@math.nagoya-u.ac.jp>
Cc: diego-olivier.fernandez-pons@cicrp.jussieu.fr, <caml-list@inria.fr>
Subject: Re: [Caml-list] Equality/Hashtable for functions (inline help feature)
Date: Thu, 7 Sep 2006 12:31:57 +0200 (DST) [thread overview]
Message-ID: <Pine.A41.4.44.0609071220520.1466470-100000@ibm1> (raw)
In-Reply-To: <20060907.091948.56533867.garrigue@math.nagoya-u.ac.jp>
Bonjour,
> Note that you cannot use hashtables, as the default hash function will
> fail on functions, but you can use an association list with physical
> equality.
I dont understand why the hash function fails on functions. When I call
Hashtbl.hash : 'a -> int with a function I get an integer. Does it mean
the integer could change while the program is running ?
# Hashtbl.hash (fun x -> x + 1);;
- : int = 151020553
# Hashtbl.hash (fun x -> x + 2);;
- : int = 151020609
# Hashtbl.hash (fun x y -> x + y);;
- : int = 151020669
I had in mind a reduction of the search space based on the hash value and
an association list with physical equallity test on the functions that
have the same hash (collisions).
Diego Olivier
next prev parent reply other threads:[~2006-09-07 10:32 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-09-06 13:36 make[1]: warning: Clock skew detected. Your build may be incomplete Mattias Waldau
2006-09-06 15:15 ` [Caml-list] " skaller
2006-09-06 16:01 ` Igor Peshansky
2006-09-06 17:19 ` Mattias Waldau
2006-09-06 17:50 ` Equality/Hashtable for functions (inline help feature) Diego Olivier Fernandez Pons
2006-09-07 0:19 ` [Caml-list] " Jacques Garrigue
2006-09-07 10:31 ` Diego Olivier Fernandez Pons [this message]
2006-09-07 0:23 ` [Caml-list] make[1]: warning: Clock skew detected. Your build may be incomplete Jacques Garrigue
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