A little F# for you
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leppie wrote:
Wouldnt that just destructure your input list into 'head' and 'tail' variable? Perhaps the '::' has special meaning?
Keep in mind, I've only been studying F# for a few days now. But, my current understanding is that F# uses the x::y syntax for dealing with its "list" type. You can create a list, or pull one apart, with that :: operator. AFAIK, writing "head::tail" (or foo::goo) is a way of saying "Give me the first cell in the list, and then also give me the remainder of the list."
:josh: My WPF Blog[^] Without a strive for perfection I would be terribly bored.
Ahh so it similar to to Scheme/Lisp's
.operator :)xacc.ide
The rule of three: "The first time you notice something that might repeat, don't generalize it. The second time the situation occurs, develop in a similar fashion -- possibly even copy/paste -- but don't generalize yet. On the third time, look to generalize the approach." -
Josh Smith wrote:
I've only scratched the surface.
of WPF or F#?:rolleyes:
Co-Author ASP.NET AJAX in Action
Rama Krishna Vavilala wrote:
of WPF or F#?
I meant WPF. I don't even know where the surface of F# is yet! :)
:josh: My WPF Blog[^] Without a strive for perfection I would be terribly bored.
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Pete O'Hanlon wrote:
Grown bored with WPF now have you?
Argh! Don't say that!! I, too, feel that I "must remain" pidgeon-holed into WPF. But I don't want to feel trapped like that. I am a bit tired of WPF at the moment, considering that I've studied nothing else for the past two years! Plus, part of my agenda[^] is to see if/how F# and WPF can work together.
Pete O'Hanlon wrote:
No challenges left there?
Yeah right. I've only scratched the surface.
:josh: My WPF Blog[^] Without a strive for perfection I would be terribly bored.
Josh Smith wrote:
Plus, part of my agenda[^] is to see if/how F# and WPF can work together.
ahhhh... WPF# eh? :-D
_________________________ Asu no koto o ieba, tenjo de nezumi ga warau. Talk about things of tomorrow and the mice in the ceiling laugh. (Japanese Proverb)
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Josh Smith wrote:
Plus, part of my agenda[^] is to see if/how F# and WPF can work together.
ahhhh... WPF# eh? :-D
_________________________ Asu no koto o ieba, tenjo de nezumi ga warau. Talk about things of tomorrow and the mice in the ceiling laugh. (Japanese Proverb)
El Corazon wrote:
WPF# eh?
If I throw in some C++ somewhere, I could be the master of WPF#++
:josh: My WPF Blog[^] Without a strive for perfection I would be terribly bored.
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I know you are but what am I... :laugh:
-- If you view money as inherently evil, I view it as my duty to assist in making you more virtuous.
dan neely wrote:
I know you are but what am I...
That's what she said! ;P
:josh: My WPF Blog[^] Without a strive for perfection I would be terribly bored.
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Chris Maunder wrote:
That looks like a huge advancement in clarity and code maintainability.
Hahaha. Yeah right. I get the feeling that F# isn't going to become a "mainstream" .NET language anytime soon. It's out there: far, far out there. It has virtues different from clarity and code maintainability. I'm just a newbie so don't quote me, but supposedly using F# as a functional programming language allows you to more easily write code which can be parallelized across multiple processors or cores. I'm interested to see how to do that, because I think that's an important aspect of modern software design.
:josh: My WPF Blog[^] Without a strive for perfection I would be terribly bored.
It's for problems where you indicate what you want performed on every member of a list (map) or how you aggregate the contents of a list (reduce). In theory, because each of the operations is atomic (independent of the other items), in the case of the map operation, or the result of reducing the whole list is the same as reducing distinct subparts of the list then reducing the results of those suboperations, you can farm out subparts of the list to other cores to execute in parallel. Because it's implicit, the environment can scale the algorithm appropriately to the number of installed cores. Still, it's not much that a parallel foreach couldn't do. It's just we're not used to writing our programs as such discrete blobs of functionality, effectively putting half your program out-of-line. And I'm not sure that many of the programs we regularly use would benefit - your data set would have to be pretty big to overcome the cost of the inter-thread procedure calling required to get another core working on part of the problem. I'm not totally sure the MHz myth is as over as it seemed a few years ago. The 45nm generation with high-k dielectric looks like it may have solved or at least alleviated the leakage problems that caused such trouble with overheating when trying to ramp up the clock speeds. The Core 2 Duo E8500 is supposed to clock at 3.16GHz while keeping a Thermal Design Power of 65W (source[^]).
DoEvents: Generating unexpected recursion since 1991 -
The daft thing is that they could have designed the syntax to be clear and maintainable, but instead went down the path of ghastly and even more ghastly.
Me: Can you see the "up" arrow? User:Errr...ummm....no. Me: Can you see an arrow that points upwards? User: Oh yes, I see it now! -Excerpt from a support call taken by me, 08/31/2007
Typical nonsense from academia.
Software Zen:
delete this; -
El Corazon wrote:
WPF# eh?
If I throw in some C++ somewhere, I could be the master of WPF#++
:josh: My WPF Blog[^] Without a strive for perfection I would be terribly bored.
Josh Smith wrote:
I could be the master of WPF#++
add in some objective capability and you will have OOWPF#++ and then you are on your first steps to writing in Malbolge[^] (see dan's post above)
_________________________ Asu no koto o ieba, tenjo de nezumi ga warau. Talk about things of tomorrow and the mice in the ceiling laugh. (Japanese Proverb)
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I've been studying F# a lot recently and find it really mind-bending. Tomas Petricek, a fellow CPian, let me sneak preview his series of F# articles and they are very good. I took one of his examples and modified it a bit. The following code displays "sum = 6", but how that happens is other-worldly...check it out:
#light
let rec sum nums =
match nums with
| head::tail -> head + sum(tail)
| [] -> 0
printf "sum = %i" (sum [1; 2; 3])Weird, eh? F# is coooool. :cool:
:josh: My WPF Blog[^] Without a strive for perfection I would be terribly bored.
So it seems we have a long way to learn it.;)
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OK, F# isn't going to be a one night stand.
More like waking up the next morning and wondering what species is laying next to you.
Software Zen:
delete this; -
It's for problems where you indicate what you want performed on every member of a list (map) or how you aggregate the contents of a list (reduce). In theory, because each of the operations is atomic (independent of the other items), in the case of the map operation, or the result of reducing the whole list is the same as reducing distinct subparts of the list then reducing the results of those suboperations, you can farm out subparts of the list to other cores to execute in parallel. Because it's implicit, the environment can scale the algorithm appropriately to the number of installed cores. Still, it's not much that a parallel foreach couldn't do. It's just we're not used to writing our programs as such discrete blobs of functionality, effectively putting half your program out-of-line. And I'm not sure that many of the programs we regularly use would benefit - your data set would have to be pretty big to overcome the cost of the inter-thread procedure calling required to get another core working on part of the problem. I'm not totally sure the MHz myth is as over as it seemed a few years ago. The 45nm generation with high-k dielectric looks like it may have solved or at least alleviated the leakage problems that caused such trouble with overheating when trying to ramp up the clock speeds. The Core 2 Duo E8500 is supposed to clock at 3.16GHz while keeping a Thermal Design Power of 65W (source[^]).
DoEvents: Generating unexpected recursion since 1991Thanks Mike. That's a very informative post. I think I'll read it again now. :)
:josh: My WPF Blog[^] Without a strive for perfection I would be terribly bored.
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That looks like a huge advancement in clarity and code maintainability. (Where's the sarcasm icon when I need it)
cheers, Chris Maunder
CodeProject.com : C++ MVP
Chris Maunder wrote:
Where's the sarcasm icon when I need it
If you can't do anything about it, you expect us to help you find one? ;P
_________________________ Asu no koto o ieba, tenjo de nezumi ga warau. Talk about things of tomorrow and the mice in the ceiling laugh. (Japanese Proverb)
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Pete O'Hanlon wrote:
Grown bored with WPF now have you?
Argh! Don't say that!! I, too, feel that I "must remain" pidgeon-holed into WPF. But I don't want to feel trapped like that. I am a bit tired of WPF at the moment, considering that I've studied nothing else for the past two years! Plus, part of my agenda[^] is to see if/how F# and WPF can work together.
Pete O'Hanlon wrote:
No challenges left there?
Yeah right. I've only scratched the surface.
:josh: My WPF Blog[^] Without a strive for perfection I would be terribly bored.
I'm going to be studying TIDDLY WINQS[^].
Deja View - the feeling that you've seen this post before.
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More like waking up the next morning and wondering what species is laying next to you.
Software Zen:
delete this;It's been so long since that's happened.
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Justin Perez wrote:
stop listenting to that crap
:suss: ... ... ... ...I almost didn't change it, you know...'Mmmbop' is fun! You're killing my zest for life.
"Who wants waffles? We got a new album out...it's called 10,000 Days. Buy it so I can afford waffles." -Maynard James Keenan
Ravel H. Joyce wrote:
"Who wants waffles? We got a new album out...it's called 10,000 Days. Buy it so I can afford waffles." -Maynard James Keenan
Tool is the best. Maynard is a genius.
I didn't get any requirements for the signature
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That looks like a huge advancement in clarity and code maintainability. (Where's the sarcasm icon when I need it)
cheers, Chris Maunder
CodeProject.com : C++ MVP
That is just what I was thinking. What a load of crap for code. Why not just write a function that takes a list and it sums everything in between? Sure would look cleaner. Gosh anything would look cleaner compared to that. I've seen pascal code that did more with less.
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I've been studying F# a lot recently and find it really mind-bending. Tomas Petricek, a fellow CPian, let me sneak preview his series of F# articles and they are very good. I took one of his examples and modified it a bit. The following code displays "sum = 6", but how that happens is other-worldly...check it out:
#light
let rec sum nums =
match nums with
| head::tail -> head + sum(tail)
| [] -> 0
printf "sum = %i" (sum [1; 2; 3])Weird, eh? F# is coooool. :cool:
:josh: My WPF Blog[^] Without a strive for perfection I would be terribly bored.
Wow... The F# code just gave me a lisp flashback (car (cdr (cons ... ))))))))) :wtf: Functional but unreadable. Don't worry though, I'm better now.
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Thats simply a map/reduce pattern, also called folding. Here is a Scheme example:
(define (fold func accum lst)
(if (null? lst)
accum
(fold func (func accum (car lst)) (cdr lst))))(define (sum . lst) (fold + 0 lst))
(display "sum = ")
(display (sum 1 2 3)) ; prints 6 (0 + 1 + 2 + 3)
(newline)(define (product . lst) (fold * 1 lst))
(display "product = ")
(display (product 1 2 3)) ; prints 6 (1 * 1 * 2 * 3)xacc.ide
The rule of three: "The first time you notice something that might repeat, don't generalize it. The second time the situation occurs, develop in a similar fashion -- possibly even copy/paste -- but don't generalize yet. On the third time, look to generalize the approach."Wow. That takes me back. Haven't seen that stuff since college.
"If you think of yourselves as helpless and ineffectual, it is certain that you will create a despotic government to be your master. The wise despot, therefore, maintains among his subjects a popular sense that they are helpless and ineffectual." - Frank Herbert
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That looks like a huge advancement in clarity and code maintainability. (Where's the sarcasm icon when I need it)
cheers, Chris Maunder
CodeProject.com : C++ MVP
(Where's the sarcasm icon when I need it) This is all we got to work with: :rolleyes:
Christianity: The belief that a cosmic Jewish zombie who was his own father can make you live forever if you symbolically eat his flesh and telepathically tell him you accept him as your master, so he can remove and evil force from your soul that is present in humanity because a rib-woman was convinced by a talking snake to eat from a magical tree... yeah, makes perfect sense.
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It's been so long since that's happened.
Brady Kelly wrote:
It's been so long since that's happened.
What are we talkin', days? weeks?
:josh: My WPF Blog[^] Without a strive for perfection I would be terribly bored.