Hi everybody, I have landed on a small problem.

I have a list of length n, and a function ([Double] -> Double) that requires a list of length n.

I want to use them with a my plotting function that takes a function (Vector n Double -> Double) and a (Vector n Double) where both n represent same length.

I convert the known function to a new function

newFunc = f . toList :: Vec pn Double -> Double

-- Where pn is the peano encoding of n

I then convert the list to a vector using fromList, but then I cannot pass them both to my plotting function.

In other words, how can I convince the type system that the length of provided vector is the same as that required by the function.

On 12 March 2015 at 14:12, Sumit Sahrawat, Maths & Computing, IIT (BHU) <sumit.sahrawat.apm13@iitbhu.ac.in> wrote:

Yeah, Data.Vector.Fixed.toList worked. I had found it previously, but it didn't work for Vec imported from Data.Fixed.Vector.Primitive (as (Double, Double) doesn't have a Prim instance).
Then I had to switch to Data.Fixed.Vector.Unboxed, and it works now.

Also, those shingles look interesting too. Thanks everybody.

On 12 March 2015 at 12:35, Konstantine Rybnikov <k-bx@k-bx.com> wrote:
Is `Data.Vector.Fixed.toList` is what you're looking for?

On Thu, Mar 12, 2015 at 1:16 AM, Sumit Sahrawat, Maths & Computing, IIT (BHU) <sumit.sahrawat.apm13@iitbhu.ac.in> wrote:
The fixed-vector package uses a similar technique. The only trouble I'm having is with converting Vec v (Double, Double) to [(Double, Double)] for further use. I don't want to change all the code, but only the part where the user provides me with arguments.

I'll keep looking into it. Thanks for the help.

On 12 March 2015 at 04:44, David Feuer <david.feuer@gmail.com> wrote:
There are a lot of ways to do this sort of thing, and which one you choose will depend on exactly what you're trying to do. For example, you can write something vaguely like

data Nat = Z | S Nat
data SL (n :: Nat) a where
Nil :: SL Z
Cons :: a -> SL n a -> SL (S n) a

plot :: forall (n::Nat) . (SL n Double -> Double) ->
SL n (Double, Double) -> IO ()

On Mar 11, 2015 5:45 PM, "Sumit Sahrawat, Maths & Computing, IIT (BHU)" <sumit.sahrawat.apm13@iitbhu.ac.in> wrote:
Hi everybody,

I have a function of type

plot :: ([Double] -> Double) -- A function to plot
-> [(Double, Double)] -- Range for all arguments
-> IO ()

I want to enforce the fact that ranges for all arguments should be provided.
Is there a way to make the type system enforce it?

--
Regards

Sumit Sahrawat

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Regards

Sumit Sahrawat

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Sumit Sahrawat

Regards

Sumit Sahrawat