Sure, you can do this easily with a GADT + DataKinds for convenient indexing with lists. The construct you need is called a heterogeneous list, or HList: http://hackage.haskell.org/package/HList-0.3.0.1/docs/Data-HList-HList.html

But it's a nice exercise to implement it on your own anyway. If you need "truly" heterogeneous lists where you can't even get the types of the elements from the index typelist then you'll need to existentially hide the types. This will simply be the same as HList without the indexing list.

Good luck

ex

On 1 December 2013 20:11, Sergey Bushnyak <sergey.bushnyak@sigrlami.eu> wrote:

Hello, everyone. I'm looking for reliable library or idea how to implement heterogenous vector properly. It may seem odd, but I want elements not only be different types but also functions, something like that, pseudocode:

    hvec [a b (c->d) [a] ...]  -- can be any type
    let hvec = hvec [ "stuff" 5 getUrl [1, 4, 5]]

So far I found *vector-heterogenous* package, but can't decide is it good to build on or create something on my own.

Any thoughts and ideas are appreciated. Thanks.

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