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From: Jon Harrop <jonathandeanharrop@googlemail.com>
To: <mark@proof-technologies.com>, <yminsky@gmail.com>,
	<arlen@noblesamurai.com>
Cc: <caml-list@inria.fr>
Subject: RE: [Caml-list] Infix function composition operator
Date: Wed, 10 Nov 2010 12:51:54 -0000	[thread overview]
Message-ID: <020e01cb80d6$0e52b890$2af829b0$@com> (raw)
In-Reply-To: <1289372378510@names.co.uk>

A pipeline operator is usually preferred over function composition in impure languages like OCaml and F# due to the value restriction. For example, your example would be written in F# as:

  x |> op1 |> op2 |> op3 |> op4 |> op5

This style is very common in F#, particularly when dealing with collections.

Cheers,
Jon.

> -----Original Message-----
> From: caml-list-bounces@yquem.inria.fr [mailto:caml-list-
> bounces@yquem.inria.fr] On Behalf Of mark@proof-technologies.com
> Sent: 10 November 2010 07:00
> To: yminsky@gmail.com; arlen@noblesamurai.com
> Cc: caml-list@inria.fr
> Subject: Re: [Caml-list] Infix function composition operator
> 
> on 10/11/10 3:45 AM, yminsky@gmail.com wrote:
> 
> > This is probably a minority opinion, but I have written and read
> quite a
> lot
> > of OCaml code over the years, and I've seen surprisingly few
> effective
> uses
> > of the composition operator.  Somehow, I usually find that code that
> avoids
> > it is simpler and easier to read.
> 
> I agree that using a composition operator can make the code obtuse, and
> so
> should not be overused.  But it's incredibly useful for certain
> situations:
> 
> 1) If you are performing a long chain of composed operations, it avoids
> nested bracketing piling up.
> 
> For example:
>       (op5 <<- op4 <<- op3 <<- op2 <<- op1) x
> Instead of:
>       op5 (op4 (op3 (op2 (op1 x))))
> 
> This sort of thing happens quite a lot in certain applications, e.g. in
> language processing, to get at subexpressions.
> 
> 2) Creating an anonymous function to be passed as an argument, it
> avoids
> explicitly mentioning arguments of that function.
> 
> This sort of thing can happen a lot in functional programming
> generally.
> 
> For example:
>       List.map (op2 <<- op1) xs
> Instead of:
>       List.map (fun x -> op2 (op1 x)) xs
> 
> Mark Adams
> 
> _______________________________________________
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  reply	other threads:[~2010-11-10 12:52 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-11-10  6:59 mark
2010-11-10 12:51 ` Jon Harrop [this message]
2010-11-14 18:20   ` Till Varoquaux
  -- strict thread matches above, loose matches on Subject: below --
2010-11-10 15:18 mark
2010-11-10 13:44 mark
2010-11-10 14:13 ` Jon Harrop
2010-11-10 16:10   ` Stephan Tolksdorf
2010-11-10 17:41     ` Jon Harrop
2010-11-10 18:52       ` Stephan Tolksdorf
2010-11-10  3:19 Arlen Christian Mart Cuss
2010-11-10  3:45 ` [Caml-list] " Yaron Minsky
2010-11-10  4:37   ` Arlen Christian Mart Cuss
2010-11-10 10:06   ` DS
2010-11-10 13:23 ` Michael Ekstrand

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