On 08/31/2013 09:27 PM, Charlie Paul wrote:
I believe that this is what you want:
http://www.haskell.org/haskellwiki/Num_instance_for_functions
On Sat, Aug 31, 2013 at 10:01 PM, Christopher Howard
christopher.how...@frigidcode.com wrote:
The author seemed to be subtly mocking the idea
Hi. I was just curious about something. In one of my math textbooks I
see expressions like this
f + g
or
(f + g)(a)
where f and g are functions. What is meant is
f(a) + g(a)
Is there a way in Haskell you can make use of syntax like that (i.e.,
expressions like f + g and f * g to create a
Q: Are the continuations in Scheme related to the monads from
Haskell? If so, could someone elaborate on that?
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When I previously asked about memoization, I got the impression that
memoization is not something that just happens magically in Haskell.
Yet, on a Haskell wiki page about Memoization
http://www.haskell.org/haskellwiki/Memoization#Memoization_with_recursion,
an example given is
memoized_fib
On 07/21/2013 11:19 PM, KC wrote:
Have you tried the compiler?
No. Would that work differently some how?
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On 07/21/2013 11:52 PM, Chris Wong wrote:
[.. snipped ..]
A binding is memoized if, ignoring everything after the equals sign,
it looks like a constant.
In other words, these are memoized:
x = 2
Just x = blah
(x, y) = blah
f = \x - x + 1
-- f = ...
and these
On 07/22/2013 06:16 AM, Andreas Abel wrote:
On 22.07.2013 09:52, Chris Wong wrote:
True, but the essential thing to be memoized is not memoized_fib,
which is a function, but the subexpression
map fib [0..]
which is an infinite list, i.e., a value.
The rule must be like in
let x = e
On 07/22/2013 03:41 PM, David Thomas wrote:
I, for one, would love to have a compiler do (a) based on (b), my
specification of (c), and the ability to pin particular things...
The reason it is a big deal to me is it sometimes the more
natural-looking (read, declarative) way of writing a
Hi. For learning, I was doing the phone words problem, where a
function translates the digits of a phone number into all possible
words. I am trying to connect this idea to the idea of list
comprehensions / list monads (sort of the same thing, yes?)
I know it is easy to do this:
w = do two - ABC
Hi. I am working on some practice programming problems, and one is the
Roman numeral problem: write a program that converts Roman numerals into
their (arabic) numeral equivalent. I imagine I could hack something
together, but I was trying to think about the problem a bit more deeply.
I don't know
I'm working through some beginner-level keyboard problems I found at
users.csc.calpoly.edu. One problem is the Saddle Points problem:
quote:
Write a program to search for the saddle points in a 5 by 5 array of
integers. A saddle point is a cell whose value is greater than or equal
to any
On 06/15/2013 04:39 PM, Tommy Thorn wrote:
There's not enough context to answer the specific question,
but lazy evaluation isn't magic and the answer is probably no.
Tommy
Perhaps to simplify the question somewhat with a simpler example.
Suppose you have
code:
let f x = if (x
On 06/15/2013 05:02 PM, Christopher Howard wrote:
On 06/15/2013 04:39 PM, Tommy Thorn wrote:
Perhaps to simplify the question somewhat with a simpler example.
Suppose you have
code:
let f x = if (x 4) then f 0 else (sin x + 2 * cos x) : f (x + 1)
After calculating
On 05/31/2013 07:47 PM, Tikhon Jelvis wrote:
My favorite mini app is John Conway's game of life. I implemented a
version with reactive banana and found it perfect for learning the ideas.
I have a simple version of the code up on GitHub if you ever want a nice
example to read. I tried to make
I want to learn FRP but am having trouble wading through all the theory
about how FRP is implemented and how it /could/ be used for various
applications. What is the simplest, easiest-to-learn module or system
allowing you to quickly make something interesting (if not very
impressive) in an FRP
On 05/19/2013 10:10 PM, Tillmann Rendel wrote:
This is not easily possible. If you could just put the constraint into
the instance, there would be a problem when youc all toXy in a
polymorphic context, where a is not known. Example:
class XyConv a where
toXy :: a b - [Xy b]
Hi. I won't pretend to be an advanced Haskell programmer. However, I
have a strong interest in abstraction, and I have been playing around
with programming as abstractly as possible. Naturally, I find classes to
be quite attractive and useful.
However, something is bothering me. Lately I keep
This is probably a haskell-beginners sort of question, but I usually get
about 4x as many responses from cafe, about 10x as fast.
I have code like so:
code:
data Xy a = Xy a a
class Coord2 a where
coords2 :: Fractional b = a b - Xy b
data CircAppr a b = CircAppr a b b -- number of
On 05/13/2013 02:53 PM, Tom Ellis wrote:
On Mon, May 13, 2013 at 11:43:41PM +0100, Tom Ellis wrote:
You probably want
let angles = map ((* dAng) . fromInteger) [0..divns] in
...
instead.
Ah, that works. Thanks all.
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Hi. Does Haskell allow you to flip around type parameters somehow? I was
playing around with toy code (still learning the fundamentals) and I
came up with a class like this:
code:
class Rotatable2D a where
rotate :: (Num b) = (a b) - b - (a b)
It was easy to make an
Has anybody on the list been playing around with OpenCL at all? I'm just
starting to look into it - need to get a newer Radeon card, I think -
but I'm strongly interested in GPGPU programming.
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Hi. This question dovetails off my previous thread. I described how I
got ghc-7.6.3 installed from source onto an old RHEL5 machine.
Naturally, I want to get cabal-install installed and start building
great Hackage software. However, I have this quirk: I installed GHC to a
special directory using
On 05/01/2013 12:21 AM, Gabor Greif wrote:
Am 27. April 2013 um 07:21 schrieb Christopher Howard
christopher.how...@frigidcode.com:
I can feel your pain... Here is a blog post I have written some time ago
http://heisenbug.blogspot.de/2011/09/ghc-704-on-centos.html
about how to bridge
Hey guys, this probably isn't the official GHC mailing list, but I've
been trying to build and install a new GHC on an old RHEL5 system, as
mentioned in my previous Cafe thread. I was able to make some good
headway: I installed a ghc-6.8 binary, and then used that to build
ghc-6.10 source, and
On 04/27/2013 08:36 AM, Jerzy Karczmarczuk wrote:
Christopher Howard:
Is the portability which worries you, or the age of your system?
Actually getting a successful build and installation would be great.
Also, there are multiple systems I work with, both of which have ancient
software
Hi. I've got this work situation where I've got to do all my work on
/ancient/ RHEL5 systems, with funky software configurations, and no root
privileges. I wanted to install GHC in my local account, but the gnu
libc version is so old (2.5!) that I can't even get the binary packages
to install.
So, I'm doing something like this
foldl (=) someA list :: Monad m = m a
where
list :: Monad m = [a - m a],
someA :: Monad m = m a
Is there a more concise way to write this? I don't think foldM is what I
want -- or is it?
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I asked this question in Haskell-beginners, but I haven't heard anything
yet, so I'm forwarding to Cafe.
Original Message
Subject: [Haskell-beginners] Monad instances and type synonyms
Date: Sat, 13 Apr 2013 17:03:57 -0800
From: Christopher Howard christopher.how
On 04/11/2013 06:37 AM, Brandon Allbery wrote:
On Thu, Apr 11, 2013 at 1:38 AM, Christopher Howard
christopher.how...@frigidcode.com
mailto:christopher.how...@frigidcode.com wrote:
Hi. For my own learning, I wanted to see how the exp function is
implemented in GHC. I have GHC 7.4.1
On 04/11/2013 07:12 AM, Christopher Howard wrote:
On 04/11/2013 06:37 AM, Brandon Allbery wrote:
I traced it down some more: I think it eventually goes into the
compiler/nativeGen section where it is translated into the platform's
native version of the function. On my platform, I think
Hi. For my own learning, I wanted to see how the exp function is
implemented in GHC. I have GHC 7.4.1 source code open, but I'm having
trouble figuring out which file the actual function definition is in. I see
expFloat(F# x) = F# (expFloat# x)
in libraries/base/GHC/Float.lhs.
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I made a nice little pattern from just a few lines of Haskell (mostly
code comments) using gloss. It is very kindergarten in terms of
mathematical art, but the idea was to illustrate that in a pretty short
amount of time, and a small amount code, you could easily translate
simple math concepts
Hi. My Haskell is (sadly) getting a bit rusty. I was wondering what
would be the most straightforward and easily followed procedure for
translating a recursively defined sequence into a Haskell function. For
example, this one from a homework assignment.
quote:
a_1 = 10
a_(k+1) = (1/5) *
On 03/04/2013 08:36 PM, Bob Ippolito wrote:
I suppose it depends on your definition of straightforward but you can
use the iterate function from Data.List to quickly define sequences like
this.
a = iterate (\x - (1/5) * (x**2)) 10
On Mon, Mar 4, 2013 at 9:19 PM, Christopher Howard
Hi. The scope of this question is likely bigger that Haskell, but this
seems like the right crowd to ask. I'm in Calc II right now, and I'm
looking for a FOSS desktop application (I use Gnu/Linux) to replace the
functionality of my TI-98 in finding derivatives and integrals. (It's
very convenient
On 01/13/2013 03:15 AM, Alfredo Di Napoli wrote:
Morning Cafe,
I'm planning to do a series of write-ups about Category Theory, to
publish them on the company's blog I'm currently employed.
I'm not a CT expert, but since the best way to learn something is to
explain it to others, I want to
Hi. Are natural log and Euler's constant defined somewhere in base, or a
convenience math module somewhere? I'm having trouble finding them with
hayoo or system documentation.
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I'm working through a video lecture describing how to prove programs
correct, by first translating the program into a control flow
representation and then using propositional logic. In the control flow
section, the speaker described how the program should be understood in
terms of an input vector
On 12/20/2012 08:54 PM, Daniel Feltey wrote:
You were only missing the restriction that both types a and b must be
instances of Monoid in order to make Socket a b into an instance of Monoid.
Dan Feltey
Thank you for your help. An additional question, if I might: For the
sake of elegance
Using a simple type I gave earlier from my monadic type question...
code:
data Socket3 a b c = Socket3 a b c
deriving (Show)
Is it possible somehow to layer on record syntax onto a synonym of the type?
The idea would be something like this...
code:
type SpaceShip =
On 12/21/2012 04:52 AM, Daniel Trstenjak wrote:
Why having a Socket3 in the first place, what's the point of it?
The idea was to have some generic structures (Sockets) which were
already instanced into the Monoids-within-Monoids abstraction, yet could
still be made concrete into anything
I've perhaps been trying everyones patiences with my noobish CT
questions, but if you'll bear with me a little longer: I happened to
notice that there is in fact a Category class in Haskell base, in
Control.Category:
quote:
class Category cat where
A class for categories. id and (.)
On 12/20/2012 03:59 AM, wren ng thornton wrote:
On 12/20/12 6:42 AM, Christopher Howard wrote:
As mentioned in my other email (just posted) the kind mismatch is
because categories are actually monoid-oids[1] not monoids. That is:
class Monoid (a :: *) where
mempty
In my current pondering of the compose-able objects them, I was thinking
it would be useful to have the follow abstractions: Monoids, which were
themselves tuples of Monoids. The idea was something like so:
code:
import Data.Monoid
instance Monoid (Socket2 a b) where
mempty = Socket2
On 12/17/2012 06:30 PM, Richard O'Keefe wrote:
On 18/12/2012, at 3:45 PM, Christopher Howard wrote:
It's basically the very old idea that an Abstract Data Type
should be a nice algebra: things that look as though they
ought to fit together should just work, and rearrangements
of things
Is there some good data type out there that basically provides a simple
table, but with optimization for repeating values on one column?
Something like:
Data Table a b
...where it assumes that 'a' values will usually be unique, while 'b'
values will usually be repeated from a small set? (But not
On 12/18/2012 08:02 PM, Gershom Bazerman wrote:
On 12/17/12 9:45 PM, Christopher Howard wrote:
I don't think you're describing a Category in the sense of the Haskell
Category typeclass. But that's ok! Just because some things are
categories and are nice doesn't mean that we can't have other
I gave Shelly a try. Pretty cool - using it for some of the scripts on
my system. Has me wondering though: is anyone working on creating a
actual Haskell-like scripting language and engine?
Shelly is cool, as I said, but I imagine it would be more valuable to
have another language that is
Recently I read this article I happened across, about the categorical
design pattern:
http://www.haskellforall.com/2012/08/the-category-design-pattern.html
Barely understood it, of course, but it was a rather intriguing concept.
So now I'm looking at all my programming problems trying to make
Hey guys, to teach myself Haskell I wrote a little arcade game called
The Edge, built on gloss. It is in hackage under the package name
edge. Are there a few kind souls who would be willing to compile it on
their machines and let me know if there are any problems at the
compiling level? In the
On 12/14/2012 07:05 PM, Clark Gaebel wrote:
Unacceptable argument type in foreign declaration
Thanks for giving it a try. Could you send off a bug report to the
OpenAL Haskell module maintainer? sven.pa...@aedion.de
(I might offer to do it, but I tried to e-mail him once about a
different issue
On 12/13/2012 08:34 AM, Clint Adams wrote:
On Wed, Dec 12, 2012 at 11:11:28PM -0800, Chris Smith wrote:
That's true. However, haskell.org's fiscal sponsor receives pro bono
legal services.
I may have been conflating threads, though the response to what I assume
was just a lawyer asking
On 12/13/2012 05:54 PM, Richard O'Keefe wrote:
On 14/12/2012, at 7:45 AM, Christopher Howard wrote:
Intimately familiar with New Zealand law, are they?
I couldn't say anything about that, specifically. However, SFLC has an
international outreach. From 2011 SFLC news:
quote:
We
I'm at something of a crossroads, and I'm hoping to get a bit of free
career advice. I really enjoy programming with Haskell (and a few other
exotic languages), and was hoping I could eventually make a living in
that sort of field. Not rich and famous, necessarily, just enough to get
by
Hi. I was wondering what the various (and especially most simple)
approaches one could take for working with (simulating or calculating)
sequential logic in Haskell. By sequential logic, I mean like wikipedia
describes, where a system is made up of logic gates, whose output is
dependent not only
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