Re: [xsl] Re: Keeping a running total?

["Colin Adams" <colinpauladams@xxxxxxxxxxx>]

This is the normal situation for functional (as opposed to imperative) 
languages.

Benefits:

1) Transparency - it is far easier to reason about a program that is free 
from side effects. So
   you can prove your program is correct with less effort.
2) Scalability - pure (side-effect free) programs are much easier to 
parallelize
3) Learning - variables in functional programs are the same as variables in 
mathematics - you don't
                  have to learn a new concept (assingment)
4) Debugging - no need to monitor when a variable changes value.
5) Power - you can bind a variable to a function definition, then it can be 
passed as the argument
               of a function (see FXSL)

Downsides:

1) Performance - functional languages are stil slower than imperative 
languages, although the gap is closing.
2) Large scale program structure - OO programming seems to have the 
advantage here.

> From: Steve <subsume@xxxxxxxxx>
> Reply-To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject: Re: [xsl] Re: Keeping a running total?
> Date: Wed, 12 Jul 2006 12:52:59 -0400
>
> Forgive me for the tangent, especially if it sounds ignorant, but as a
> newbie to XSL I have a hard time understanding the benefit in not
> being able to redefine a variable.  While I do not doubt the talent
> and genius that went into the above examples and speculations, I can't
> imagine a benefit that outweighs the time economics involved in coming
> up with the above solutions, versus simply doing a $variable =
> $variable - $x and being done with it in 10ish lines.
>
> Comments welcome.
>
> -Steve

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