From: Lukasz Stafiniak <lukstafi@gmail.com>
To: Gabriel Scherer <gabriel.scherer@gmail.com>
Cc: caml users <caml-list@inria.fr>
Subject: Re: [Caml-list] List.fold_left vs. Hashtbl.fold
Date: Wed, 28 Nov 2012 18:37:19 +0100 [thread overview]
Message-ID: <CAJMfKEX37AtHzY_8o=L0LMH8PEMqeVRttn0vJQUYbiL7AGBx6Q@mail.gmail.com> (raw)
In-Reply-To: <CAPFanBHXymazXgafbSj0Skm_eOzHDJnXDBEdqf1-ebsJGavVmQ@mail.gmail.com>
On Wed, Nov 28, 2012 at 6:25 PM, Gabriel Scherer
<gabriel.scherer@gmail.com> wrote:
>
> This means that fold_left may not exist for arbitrary data structure
> (think of binary trees), while fold_right is rather universal. Other
> folding functions in the standard library (in Set and Map in
> particular, but in Hashtbl as well) have therefore taken inspiration
> from the fold_right structure, rather than fold_left.
This is right, you get my "upvote". But Set and Map do not intend to
expose the structure of the underlying data structure to the folding
computation. The folds of Set and Map traverse the elements in a
sequential order. They could be a deforested variant of List.fold_left
composed with Set.elements.
next prev parent reply other threads:[~2012-11-28 17:37 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-28 4:40 William Smith
2012-11-28 16:17 ` Lukasz Stafiniak
2012-11-28 16:25 ` Malcolm Matalka
2012-11-28 16:21 ` David House
2012-11-29 1:06 ` Francois Berenger
2012-11-28 16:42 ` Oliver Bandel
2012-11-28 17:11 ` Adrien
2012-11-28 17:41 ` Virgile Prevosto
2012-11-29 0:07 ` Jacques Garrigue
[not found] ` <CAPFanBG04BiwJuPkV80__Ondmg1N8OEg4DokiXqDReg3ycNBdA@mail.gmail.com>
2012-11-28 17:25 ` Gabriel Scherer
2012-11-28 17:37 ` Lukasz Stafiniak [this message]
2012-11-30 3:06 William Smith
2012-11-30 9:53 ` Gabriel Scherer
2012-11-30 10:06 ` Stefano Zacchiroli
2012-11-30 16:00 ` Gabriel Scherer
2012-11-30 16:48 ` Daniel Bünzli
2012-11-30 11:34 ` Daniel Bünzli
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