On 02/13/2012 03:19 PM, James Miller wrote:
On 11 February 2012 10:45, Jonathan M Davis<jmdavisp...@gmx.com> wrote:
On Friday, February 10, 2012 13:32:56 Marco Leise wrote:
I know that feeling. I had no exposure to functional programming and
options like chain never come to my head. Although "map" is a concept that
I made friends with early.
It would benefit your programming in general to learn a functional programming
language and become reasonably proficient in it, even if you don't intend to
program in it normally. It'll increase the number of tools in your programming
toolbox and improve your programming in other programming languages. It's
something that not enough programmers get sufficient exposure to IMHO.
- Jonathan M Davis
I found that learning Haskell made me significantly better at what I
do. New paradigms are good for reminding you to think outside the box,
I also learnt Prolog for a university course (AI) and that was an
interesting challenge. Logical programming, where you define the
boundaries of the program and then it works out the possible answers
for you, amazingly useful for BNF grammars and similar constructs.
If fact it's got to the point where I feel hamstrung if I can't do at
least function passing (fortunately C, C++ and D can do this), and I
prefer to work with languages that support closures and anonymous
functions, since you can do wonders with simple constructs like map,
fold (reduce) and filter. In fact a naive implementation of quicksort
can be done succinctly in any language that supports filter.
T[] sort(T)(T[] array) {
pivot = array[array.length/2];
return sort(filter!("a< "~pivot)(array)~pivot~sort(filter!("a
"~pivot)(array));
}
(Disclaimer, this is probably a very slow implementation, possibly
very broken, may cause compiler demons to possess your computer, DO
NOT USE!)
I have left out some details for brevity, and it probably won't work
in alot of situations, but it demonstrates the power of functional
programming, quicksort in 4 lines (sort of, its not like Haskell's
"quicksort in 2 lines" is any better mind you, its slow as balls
because of all the memory allocation it has to do).
Anyway, yay for functional programming and thread derailment.
James
If it is slow and uses an awful lot of auxiliary memory it is not
quicksort as much as it may conceptually resemble quicksort. Try to
implement in-place quicksort in Haskell. It will look like C code. Also
see:
http://stackoverflow.com/questions/5268156/how-do-you-do-an-in-place-quicksort-in-haskell
