I agree with Dan here.
IO is important because you can't write any real program without using it.
So why not teach enough of it to get people off the ground straight away?
People who hang around long enough to do some more Haskell programming
will run into the other monads sooner or later. But
0x02 is not a Char, it's a numeric constant. Perhaps you meant '\x02' ?
On Dec 8, 2007 9:02 AM, Galchin Vasili [EMAIL PROTECTED] wrote:
Hello,
I am writing a function(actually much more than this):
bozo :: Char - Char
bozo 0x02 = 'a'
...
However, I get complaints from ghc
Hello,
I am writing a function(actually much more than this):
bozo :: Char - Char
bozo 0x02 = 'a'
...
However, I get complaints from ghc suggesting that I should add an instance
declaration (Num, Char). I (mistaking) thought I understood the Haskell
class hierarchy and the associated
Luke Palmer wrote:
Hmm, this still seems ill-defined to me.
compose :: (Int - Int - Int) - (Int - Int) - Int - Int - Int
Is a valid expression given that definition (with a,b = Int and c = Int - Int),
but now the arity is 4.
That's correct, the arity of a function is not well-defined due to
Hello,
You can compile a .html file with:
ghc --make -x lhs index.html
if you write the code like this:
code
foo = 1
/code
N.B. You need an empty line between code and the code and one between
the code and /code.
The -x flag doesn't seem to work for runhaskell, when I try this,
Hello!
I see from http://www.haskell.org/haskellwiki/Monads_as_computation#Do_notation
that
do { v - x ; stmts }
= x = \v - do { stmts }
However, look at this GHCi session:
Prelude let return' = return :: a - Maybe a
Prelude do {1 - return 1; return' ok}
Just ok
Prelude return 1 = \1 -
On Sat, Dec 08, 2007 at 02:59:16PM -0200, Felipe Lessa wrote:
Hello!
I see from
http://www.haskell.org/haskellwiki/Monads_as_computation#Do_notation
that
do { v - x ; stmts }
= x = \v - do { stmts }
However, look at this GHCi session:
Prelude let return' = return :: a - Maybe a
On Sat, Dec 08, 2007 at 03:28:58PM -0200, Felipe Lessa wrote:
On Dec 8, 2007 3:12 PM, Ilya Tsindlekht [EMAIL PROTECTED] wrote:
On Sat, Dec 08, 2007 at 02:59:16PM -0200, Felipe Lessa wrote:
Prelude do {1 - return 3; return' ok}
Nothing
Prelude return 3 = \1 - return' ok
***
Albert Y. C. Lai wrote:
Some reply posts lack In-Reply-To: References: headers because
their authors fail to choose compliant software or know the issue.
Some non-reply posts (genuinely new topic, not even digression from
existing ones) contain In-Reply-To: References: headers because
their
Tom Davies wrote:
Andrew Coppin andrewcoppin at btinternet.com writes:
[snip]
You might like to look at OpenQuark: http://labs.businessobjects.com/cal/
-- its 'GemCutter' provides a visual environment for linking together functions
written in a Haskell-like language.
I'm not sure if it would
Denis Bueno wrote:
Do you need to update positions of the units in real time? Do they
even evolve over time, or are you just trying to visualise?
If it's the latter, you might just take a collection of units and
connections between them, output them in the graphviz [0] format, and
see the
hi
I have a problem.
Function A is a function that passes its input into B
Function B is a function that does something once.
How do I make it so function A is done multiple times without adding a third
function?
Ryan
_
On Dec 8, 2007 7:41 PM, Ryan Bloor [EMAIL PROTECTED] wrote:
hi
I have a problem.
Function A is a function that passes its input into B
Function B is a function that does something once.
What do you mean by that? B does something once.
More details! (Type signatures at least will give
Albert Y. C. Lai wrote:
Andrew Coppin wrote:
Thunderbird has a long-standing bug in that new posts having the same
subject line as some other post that happened many years ago get
added to that thread. It's really most irritating. :-S
I have investigated. A bit of skepticism goes a long way.
On 8 Dec 2007, [EMAIL PROTECTED] wrote:
Function A is a function that passes its input into B
Function B is a function that does something once.
How do I make it so function A is done multiple times without adding a
third function?
By this, do you mean that you have functions f, g
f :: a
On Dec 8, 2007 10:15 PM, Andrew Coppin [EMAIL PROTECTED] wrote:
Bit Connor wrote:
On Dec 8, 2007 8:19 PM, Andrew Coppin [EMAIL PROTECTED] wrote:
http://alts.homelinux.net/shots/195-0.jpg
This is the kind of thing I'd like to end up with.
Such a GUI would also be cool for visually
I just spent the evening writing a library that's a thin layer over
Gtk2hs. It took an age to get it to compile, but eventually it worked. Yay!
When I ran it, I got this:
Test2: gtk/Graphics/UI/Gtk/Gdk/PixbufData.hs.pp:58:0: No instance nor
default method for class operation
Albert Y. C. Lai wrote:
I can't blame you for being not observant. Afterall, this is precisely
what I'm alluding to with everyone can haz PC [...]
Please don't flame people on the list.
Thank you,
b
___
Haskell-Cafe mailing list
On Sat, Dec 08, 2007 at 08:33:36PM +, Andrew Coppin wrote:
I just spent the evening writing a library that's a thin layer over Gtk2hs.
It took an age to get it to compile, but eventually it worked. Yay!
When I ran it, I got this:
Test2: gtk/Graphics/UI/Gtk/Gdk/PixbufData.hs.pp:58:0: No
On Sat, 8 Dec 2007, Bit Connor wrote:
On Dec 8, 2007 8:19 PM, Andrew Coppin [EMAIL PROTECTED] wrote:
Andrew Coppin wrote:
Well, for starters, take a look at KLogic.
http://alts.homelinux.net/shots/195-0.jpg
This is the kind of thing I'd like to end up with.
Such a GUI would also
Bit Connor wrote:
On Dec 8, 2007 10:15 PM, Andrew Coppin [EMAIL PROTECTED] wrote:
Bit Connor wrote:
On Dec 8, 2007 8:19 PM, Andrew Coppin [EMAIL PROTECTED] wrote:
http://alts.homelinux.net/shots/195-0.jpg
This is the kind of thing I'd like to end up with.
Such a GUI would also be cool for
gracjanpolak:
Gracjan Polak gracjanpolak at gmail.com writes:
Don Stewart dons at galois.com writes:
ByteStrings have all the same operations as lists though, so you can
index, compare and take substrings, with the benefit that he underlying
string will be shared, not copied.
hi
I have four functions below: What I want to do is have a way to parse more than
one digit or more than one string head in ParseTrue. Any ideas...
removeSpace:: String - StringremoveSpace = dropWhile (`elem` space)
where space = [' ']
match :: String - String - (Bool,
Hi,
I am new to Haskell. I wrote the following code:
module Main
where
import IO
main = do
hSetBuffering stdin LineBuffering
numList - processInputs
foldr (+) 0 numList
processInputs = do
putStrLn Enter a number:
strNum - getLine
let num
Loganathan Lingappan wrote:
main = do
hSetBuffering stdin LineBuffering
numList - processInputs
foldr (+) 0 numList
The type of main is understood to be IO (), so it can't return anything.
You could work around this by rewriting the last line above as follows:
print
On Sat, 2007-12-08 at 16:39 -0800, Bryan O'Sullivan wrote:
Loganathan Lingappan wrote:
main = do
hSetBuffering stdin LineBuffering
numList - processInputs
foldr (+) 0 numList
The type of main is understood to be IO (), so it can't return anything.
You could
Thanks Bryan and Derek. This works!
Logo
- Original Message
From: Derek Elkins [EMAIL PROTECTED]
To: Bryan O'Sullivan [EMAIL PROTECTED]
Cc: Loganathan Lingappan [EMAIL PROTECTED]; haskell-cafe@haskell.org
Sent: Saturday, December 8, 2007 4:53:54 PM
Subject: Re: [Haskell-cafe] Type error
hi
test :: Parser (Char,Char) test = do x - item item
y - item return (x,y)
How come this brings an error saying that after do {} it must end with an
expression.
Ryan
_
Get free
On Dec 8, 2007, at 21:38 , Ryan Bloor wrote:
test :: Parser (Char,Char)
test = do x - item
item
The second and subsequent lines are indented too much, so are read as
a continuation of the first; which, starting with x - , is not an
expression.
--
brandon s. allbery
On Dec 8, 2007, at 21:40 , Brandon S. Allbery KF8NH wrote:
On Dec 8, 2007, at 21:38 , Ryan Bloor wrote:
test :: Parser (Char,Char)
test = do x - item
item
The second and subsequent lines are indented too much, so are read
as a continuation of the first; which, starting
On Dec 9, 2007 12:42 AM, Brandon S. Allbery KF8NH [EMAIL PROTECTED] wrote:
I neglected to say the proper indentation:
test = do x - item
item -- note, indented to match the token after
the do
y - item
return (x,y)
That is the best thing to
On Dec 9, 2007 1:01 AM, Ryan Bloor [EMAIL PROTECTED] wrote:
But what is the right way to indent...? It is so annoying, why does it
matter so much! :(
You may read http://en.wikibooks.org/wiki/Haskell/Indentation which
tries to explain in a very simple language.
--
Felipe.
hi
The code below does almost what I want but not quite! It outputs...parseInt
12444a gives...
[(EInt 1,2444a),(EInt 2,444a),(EInt 4,44a),(EInt 4,4a),(EInt 4,a)]
What I want is: [(EInt 12444, a)]
data Expr = EInt {vInt :: Int} -- integer values | EBool {vBool :: Bool} --
boolean
Well, you're choosing to parse each digit of your integer as a separate
integer, so if you want to combine them after reading you'll need to
multiply by powers of two. Or, you can just read in all the digits in one
'read' command, like this:
parseInt :: String - (Expr, String)
parseInt xs
I mean powers of *ten* :)
On Dec 8, 2007 10:48 PM, Philip Weaver [EMAIL PROTECTED] wrote:
Well, you're choosing to parse each digit of your integer as a separate
integer, so if you want to combine them after reading you'll need to
multiply by powers of two. Or, you can just read in all the
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