From: ara.t.howard@...
Date: 2006-08-10T00:03:43+09:00
Subject: Re: Language chatter

On Wed, 9 Aug 2006, Francis Cianfrocca wrote:

> Simen Edvardsen wrote:
> >
>> In mathematics and computer science, higher-order functions or
>> functionals are functions which do at least one of the following:
>>
>>     * take one or more functions as an input
>>     * output a function
>>
>> According to this definition, Ruby's standard library is filled with
>> higher order functions, as are the libraries of Ocaml, Scheme etc.
>
>
> This comment is extremely interesting. It is actually *not* the case
> that Ruby's "functions" are functions in the mathematical sense. They
> are actually objects that point to blocks of executable code or to
> closures. They have the ability to execute instructions that modify the
> contents of memory or produce other side effects so as to make visible
> the results of operations that simulate mathematical functions.
>
> But true functional languages directly expose composable mathematical
> functions (mappings from a possibly infinite domains to ranges). Pure
> functional languages don't expose any side effects at all. They are
> extremely effective at modeling computations (I once wrote a complete,
> correct qsort in 7 lines of ML) but not very good at executing
> communications or data transport tasks, which are all about side
> effects.
>
> I've often been mystified when people talk about Ruby's metaprogramming,
> closures, lambdas, etc. as constituting a "functional" programming
> style. Your comment is striking because it made me realize that perhaps
> many people who learn languages like Scheme are actually trying to apply
> the imperative, Turing-style computational model to languages that don't
> support them. And that reinforces all the more my intuition that pure FP
> is not well-suited for mainstream professional programming.
>
> Years ago, I spent a lot of time trying to teach professional
> programmers to grasp the functional style. And most people couldn't even
> let go of the concept of variables as little boxes holding readable and
> writable values. That's when I gave up on FP.

interesting.  but then you have ocaml, which is a bastard of oop/fp and
impertive features - what's wrong there?

cheers.

-a
-- 
to foster inner awareness, introspection, and reasoning is more efficient than
meditation and prayer.
- h.h. the 14th dali lama