This is the best introduction to Monads for newbies and imparative
mined that I'v ever read! For a long time I was searching for such an
excellent text on monads. Ofcourse there are many good text there. But
all of them are about mathematics and how clever the monads are. After
all most of them
Greg,
What about the following (tested with GHC 6.6)?
{-# OPTIONS -fglasgow-exts #-}
data Zero = Zero
data Succ n = Succ n
zero = Zero
one = Succ zero
two = Succ one
three = Succ two
-- etc
data Seq :: * - * where
Nil :: Seq Zero
Cons :: Succ n - Seq n - Seq
Greg Buchholz wrote:
I'm wondering about creating a data structure that has the type of
decreasing numbers.
I can try...
class Pre a b | a - b
instance Pre (Succ a) a
instance Pre Zero Zero
data (Pre a b) = Seq a = Cons a (Seq b) | Nil
decreasing = Cons three (Cons two (Cons one
I too miss the old way of handling local type variables. Previously,
local type annotations worked a lot like an additional constraint,
with type variables denoting some type. The same type variable denoted
the same type. Here's how it works in OCaml, for example:
# let pair x y = (x,y);;
val
Daniel Fischer [EMAIL PROTECTED] writes:
ghci-6.6 [prints the result of IO actions] by default
I consider printing the value when it is used in an assignment a bug.
It makes it more difficult to test laziness issues or behavior on
e.g. large files.
Anybody know why it was changed to the
Am Mittwoch, 18. Oktober 2006 09:35 schrieb Ketil Malde:
Daniel Fischer [EMAIL PROTECTED] writes:
ghci-6.6 [prints the result of IO actions] by default
I consider printing the value when it is used in an assignment a bug.
It makes it more difficult to test laziness issues or behavior on
Time to write actual code and do some measurements :)
The code attached at the end of the message gets compiled with -O2.
Writing a sample test file happens with (writeTest #columns #rows) like
in writeTest 4 50 (~7 seconds, ~770MB heap (=:-o), 3MB test file).
I assume the heap spaces from
On Oct 17, 2006, at 1:46 PM, Gregory Wright wrote:
On Oct 17, 2006, at 1:07 PM, Robert Dockins wrote:
On Oct 17, 2006, at 12:55 PM, Gregory Wright wrote:
Hi Rob,
I've built Edison 1.2.0.1 using ghc-6.6. (I'm testing the macports,
formerly darwinports, packages for the new 6.6
Hello apfelmus,
Wednesday, October 18, 2006, 3:22:31 PM, you wrote:
smaller input produces a larger output). Your 13 seconds versus 90
seconds makes this even more puzzling. But it looks like writing a CSV
file is far more expensive than reading one. Maybe it's not a good idea
to call hPut
Hello Simon,
Wednesday, October 18, 2006, 12:09:40 PM, you wrote:
Other alternatives would be: do something about partial type
signatures; or make GADT type inference more sophisticated (and
thereby perhaps less predicatable).
just one more problem is that this issue is too complicated. i'm
I think the problem comes from the fact that
let (x :: a) = rhs in expr
has two interpretations: either the programmer mainly specifies a
judgment (\Gamma |- rhs :: a) (f.i. as a guide for type inference) or he
just introduces a new variable and sees let as a sugar for
(\(x :: a) -
Brian Hulley wrote:
When you try to write an editor for Haskell (or some subset of it), you
quickly discover these areas of Haskell syntax like the above which need
to be changed to get an optimum interactive editing experience. I think
it *is* possible to adjust the Haskell grammar so that
Hello Bulat,
sorry, I just completely forgot to write down the answer for your post.
Can this be remedied? Can there be a version of writeFile which is, in a
sense, dual to getContents?
this can be solved in other way. here is a program that reads stdin
and puts to stdout lines starting
Hi!
I'm a newbie and, as a learning experience, I'm writing a feed reader
with hscurses and hxt. For the present time the feed reader just reads
a Liferea cache but, as you can imagine, I'm running into the usual
newbie problems of memory consumption and garbage collection, probably
(I'm not
On 10/18/06, Andrea Rossato [EMAIL PROTECTED] wrote:
Hi!
I'm a newbie and, as a learning experience, I'm writing a feed reader
with hscurses and hxt. For the present time the feed reader just reads
a Liferea cache but, as you can imagine, I'm running into the usual
newbie problems of memory
Stefan Holdermans [EMAIL PROTECTED] wrote:
What about the following (tested with GHC 6.6)?
and [EMAIL PROTECTED] wrote:
One way is to use existentials:
snip
Perhaps a better -- and a more general alternative -- is to use
type-level programming to its fullest.
Thanks everyone, those are
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