Functional Programming (was: Of what use is 'lambda'???)

[Delaney, Timothy]

The difference is that in *pure* functional programming, everything *only*
returns a parameter. There are no side effects of any kind.

Obviously, pure functional programming is not much use ... so functional
languages usually have a few functions which do have side effects (for
example, i/o routines). However, if you treat these as black boxes, you can
do your programming entirely functionally.

So, this means you can't have a function such as (pseudocode)

function add (a, b)
	temp = a + b
	// side effect
	a = 4
	return temp

a = 1
b = 2
c = add(a, b)

Results:
a == 4
b == 2
c == 3

If you wanted to modify a you would have to assign it directly or call a
function and assign the result to a.

> -----Original Message-----
> From: jonadab at bright.net [mailto:jonadab at bright.net]
> Sent: Monday, 25 September 2000 12:38 PM
> To: python-list at python.org
> Subject: Re: Of what use is 'lambda'???
> 
> 
> Erik Max Francis <max at alcyone.com> wrote:
> 
> > > I have a question.  What is the difference between functional
> > > programming and procedural programming?  I know I should know
> > > this, but...
> > 
> > To start with, in functional programming everything returns a value.
> 
> That's true in C and Inform, but I think both are traditionally
> regarded as procedural.  Is the difference that the returned 
> value is always significant?  Or is there more?
> 
> - jonadab
> -- 
> http://www.python.org/mailman/listinfo/python-list
>