I have fixed the problem now. In the last letter, with the Natural
class, I had not added
instance Num Natural where
(N x) - (N y) = N(x - y)
which the Ordinal class then in fact has one. Then it turns out that
it is merely the fact that "show" had some cases looking at the list
length
On 28 Mar 2008, at 03:03, Ryan Ingram wrote:
Another way to defer the evaluation of the second argument of (-+)
is like this:
(-+) :: a -> List a -> List a
x -+ y = List(f) where
f 0 = x
f k = case y of List g -> g (k-1)
This is exactly what the lazy pattern will do at compile-time. Does
On 28 Mar 2008, at 03:03, Ryan Ingram wrote:
Another way to defer the evaluation of the second argument of (-+)
is like this:
(-+) :: a -> List a -> List a
x -+ y = List(f) where
f 0 = x
f k = case y of List g -> g (k-1)
This is exactly what the lazy pattern will do at compile-time. Doe
On 28 Mar 2008, at 03:03, Ryan Ingram wrote:
Another way to defer the evaluation of the second argument of (-+)
is like this:
(-+) :: a -> List a -> List a
x -+ y = List(f) where
f 0 = x
f k = case y of List g -> g (k-1)
This is exactly what the lazy pattern will do at compile-time.
Th
Another way to defer the evaluation of the second argument of (-+) is like this:
(-+) :: a -> List a -> List a
x -+ y = List(f) where
f 0 = x
f k = case y of List g -> g (k-1)
This is exactly what the lazy pattern will do at compile-time. Does
this give you a better understanding of how lazy
On 27 Mar 2008, at 17:51, Luke Palmer wrote:
A more standard way to do this would be:
data List a = List (Ordinal -> a) Ordinal
I used
data List a = Empty | (Ordinal->a) :+ Ordinal
which might then be simplified by dropping "Empty".
Hans Aberg
__
On 27 Mar 2008, at 17:51, Luke Palmer wrote:
By your naming, am I correct in assuming that you're implementing
transfinite lists?
If so, cool!
Yes, it is an old idea I brought up now. If list length is written
also for infinite lists, then concatenated lists get indexed by the
sum of their
A few comments:
On Thu, Mar 27, 2008 at 2:55 PM, Hans Aberg <[EMAIL PROTECTED]> wrote:
> The reason I used a "data" construct was that I include the size of
> the list, excluded in order to keep the example as simple as possible:
>data List a = List(Ordinal -> a, Ordinal)
This could still b
On 27 Mar 2008, at 15:58, Miguel Mitrofanov wrote:
Hmmm, seems like your (-+) is not lazy enough.
...
You can fix it by defining (-+) as
x -+ ~(List y) = ...
Yes, this has been pointed out...
Since pattern matching is strict by default, you have
anything -+ (_|_) = (_|_)
Therefore, the
Hmmm, seems like your (-+) is not lazy enough.
Since pattern matching is strict by default, you have
anything -+ (_|_) = (_|_)
Therefore, the function, which is constantly (_|_), is a fixed point
for the equation defining h. In other words, if you define
h' x = undefined
then you have
h'
On 27 Mar 2008, at 15:32, Luke Palmer wrote:
More to the point, if List is declared as:
newtype List a = List (Integer -> a)
Instead of with "data", it also works.
The problem, as was stated, was that -+ is too strict. That is,
without the ~ there, -+ evaluates its right argument to make
On 27 Mar 2008, at 15:18, Claude Heiland-Allen wrote:
The combination of (-+) and h is too strict, this modification works:
(-+) :: a -> List a -> List a
x -+ ~(List y) = List(f) where -- lazy pattern match
f 0 = x
f k = y(k-1)
Thank you for the fast response. Yes, that might be what I
On Thu, Mar 27, 2008 at 2:18 PM, Claude Heiland-Allen
> The combination of (-+) and h is too strict, this modification works:
>
>
> (-+) :: a -> List a -> List a
> x -+ ~(List y) = List(f) where -- lazy pattern match
>
>f 0 = x
>f k = y(k-1)
More to the point, if List is declared as:
Hans Aberg wrote:
When experimenting with list index sets (i.e. lists more general than
provided by Haskell), I arrived at the problem that in the example code
below for example
h(list 6)
does not (in Hugs) write out the beginning of the list lazily. It does
work for
list 6
first (list
When experimenting with list index sets (i.e. lists more general than
provided by Haskell), I arrived at the problem that in the example
code below for example
h(list 6)
does not (in Hugs) write out the beginning of the list lazily. It
does work for
list 6
first (list 6)
rest (list
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