I believe the exercise is about understanding folds.
There are two references that are related to the exercise:
A tutorial on the universality and expressiveness of fold, by Graham Hutton.
Dealing with large bananas, by Ralf Lammel, etc.
The last paper motivates well the need to gather all t
Yes,as I said before to other of you
the exp data type was also declared in the exercise (my fault not to say
it), and look as this:
data Exp = LitI Int
|LitB Bool
|Add Exp Exp
|And Exp Exp
|If Exp Exp Exp
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On Dec 3, 2007 12:18 PM, Carlo Vivari <[EMAIL PROTECTED]> wrote:
>
> Hi! I'm a begginer in haskell and I have a problem with an exercise, I
> expect
> someone could help me:
>
> In one hand I have a declaration of an algebra data, like this:
>
> data AlgExp a = AlgExp
> { litI :: Int -> a,
> li
Brent Yorgey wrote:
>
>
> One comment: it looks like (add exp1 exp2), (and exp1 exp2) and so on
> above
> are not correct. The second argument of foldExp is a value of type Exp,
> so
> you are pattern-matching on the constructors of Exp, and constructors are
> always uppercase. Perhaps Exp h
Ryan Ingram wrote:
> On 12/3/07, Kalman Noel <[EMAIL PROTECTED]> wrote:
> > You're confusing sum and product types.
> I'm not so sure; it looks like they already have that type (Exp) and wants
> to use AlgExp to hold the "folding" functions used.
Ah, I didn't catch that on the first read. I suppo
On Mon, Dec 03, 2007 at 09:27:45PM -0600, Derek Elkins wrote:
> On Mon, 2007-12-03 at 19:13 -0800, Stefan O'Rear wrote:
> > On Mon, Dec 03, 2007 at 09:18:18AM -0800, Carlo Vivari wrote:
> > >
> > > Hi! I'm a begginer in haskell and I have a problem with an exercise, I
> > > expect
> > > someone c
On Mon, 2007-12-03 at 19:13 -0800, Stefan O'Rear wrote:
> On Mon, Dec 03, 2007 at 09:18:18AM -0800, Carlo Vivari wrote:
> >
> > Hi! I'm a begginer in haskell and I have a problem with an exercise, I
> > expect
> > someone could help me:
> >
> > In one hand I have a declaration of an algebra data
On Mon, Dec 03, 2007 at 09:18:18AM -0800, Carlo Vivari wrote:
>
> Hi! I'm a begginer in haskell and I have a problem with an exercise, I expect
> someone could help me:
>
> In one hand I have a declaration of an algebra data, like this:
>
> data AlgExp a = AlgExp
> { litI :: Int -> a,
>litB
>
> foldExp :: AlgExp a -> Exp -> a
> foldExp alg (LitI i) = litI alg i
> foldExp alg (LitB i) = litB alg i
> foldExp alg (add exp1 exp2) = ¿¿¿???
> foldExp alg (and exp1 exp2) = ¿¿¿???
> foldExp alg (ifte exp1 exp2 exp3) = ¿¿¿???
>
One comment: it looks like (add exp1 exp2), (and exp1 exp2) and s
On 12/3/07, Kalman Noel <[EMAIL PROTECTED]> wrote:
>
> You're confusing sum and product types. That is, you're using a product
> type,
> but you probably need a sum type, like this:
I'm not so sure; it looks like they already have that type (Exp) and wants
to use AlgExp to hold the "folding" func
Carlo Vivari wrote:
> data AlgExp a = AlgExp
> { litI :: Int -> a,
>litB :: Bool -> a,
>add :: a -> a -> a,
>and :: a -> a -> a,
>ifte :: a -> a -> a -> a}
You're confusing sum and product types. That is, you're using a product type,
but you probably need a sum type, like this:
Hi! I'm a begginer in haskell and I have a problem with an exercise, I expect
someone could help me:
In one hand I have a declaration of an algebra data, like this:
data AlgExp a = AlgExp
{ litI :: Int -> a,
litB :: Bool -> a,
add :: a -> a -> a,
and :: a -> a -> a,
ifte :: a -> a -
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