Re: [R] The meaning of functional language

From: Berton Gunter <gunter.berton_at_gene.com>
Date: Wed 19 Oct 2005 - 08:37:25 EST


'functional' languages derive from LISP and the lamda-calculus. These are standard topics in CS computer language courses. You can look them up in Wikipedia, or Google for other sources.

"The business of the statistician is to catalyze the scientific learning process." - George E. P. Box    

> -----Original Message-----
> From: r-help-bounces@stat.math.ethz.ch
> [mailto:r-help-bounces@stat.math.ethz.ch] On Behalf Of Patrick Burns
> Sent: Tuesday, October 18, 2005 2:40 PM
> To: ronggui
> Cc: r-help@stat.math.ethz.ch
> Subject: Re: [R] The meaning of functional language
>
> ronggui wrote:
>
> >It's often heard that the S language is a functional
> language.But What's the exact meaning of this termology in
> the context of S language?
> >
> >
>
> Here's the idea. If you have:
>
> x <- 1:10
> f <- function(y) { x <- sin(y / 2); x + y}
> f(-3:3)
>
> then the 'x' inside 'f' does not wipe out your top-level 'x'
> when 'f' is called.
>
> Operationally it means that objects are only changed via
> the assignment operator. (This is not strictly true, but other
> vehicles, such as '<<-', are generally considered bad style.)
>
> The reason for wanting this behavior is so that you don't need
> to worry about objects getting invisibly changed while you
> are analyzing some data, or whatever it is that you are doing.
> That is, the language was designed to be human efficient, while
> sacrificing some machine efficiency.
>
> Patrick Burns
> patrick@burns-stat.com
> +44 (0)20 8525 0696
> http://www.burns-stat.com
> (home of S Poetry and "A Guide for the Unwilling S User")
>
>



R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Wed Oct 19 08:46:39 2005

This archive was generated by hypermail 2.1.8 : Sun 23 Oct 2005 - 19:05:05 EST