First of all I'd like to thank everyone who participated in this
discussion! Most approaches look very promising, especially the last
is what I imagined, but were unable to write. Thanks for that,
especially.
I will try to solve my problem using these approaches and report back
once I succeed or
Alexander Foremny wrote:
At first glance I noticed some problems with the vault library for my
particular approach.
Despite from being unique, Key values don't appear to carry any
information like the Label I need. However, it might be possible to
work around that.
The more grave problem seems
Hello, I made some trial and error with ghci to make it happy. I'm not
really sure this has the type safety you asked.
{-# LANGUAGE TypeFamilies, ExistentialQuantification, FlexibleContexts #-}
import Prelude hiding (lookup)
import Data.Typeable
class Typeable a = Key a where
type Value a
This is without class :-)
{-# LANGUAGE TypeFamilies, ExistentialQuantification, FlexibleContexts #-}
import Prelude hiding (lookup)
import Data.Typeable
type family Value a :: *
data Assoc = forall a . (Typeable (Value a), Typeable a) = Assoc a (Value
a)
insert :: (Typeable (Value a), Typeable
On Tue, Jul 31, 2012 at 1:13 PM, Alexander Foremny
alexanderfore...@gmail.com wrote:
Hello list,
I am currently thinking that a problem of mine would best be solved if
there was a Map-like data structure in which the value returned is
parametrized over the lookup type.
I wonder is this
Dear Michael,
thank you very much for your quick and interesting response. This
looks very much like what I want!
Regards,
Alexander Foremny
2012/7/31 Michael Snoyman mich...@snoyman.com:
On Tue, Jul 31, 2012 at 1:13 PM, Alexander Foremny
alexanderfore...@gmail.com wrote:
Hello list,
I am
At first glance I noticed some problems with the vault library for my
particular approach.
Despite from being unique, Key values don't appear to carry any
information like the Label I need. However, it might be possible to
work around that.
The more grave problem seems to be that a Key cannot be
Would ixset or HiggsSet be suitable?
http://hackage.haskell.org/package/ixsethttp://hackage.haskell.org/package/ixset-1.0.5
http://hackage.haskell.org/package/HiggsSet
On Tue, Jul 31, 2012 at 12:56 PM, Alexander Foremny
alexanderfore...@gmail.com wrote:
At first glance I noticed some problems
Another option which allows you to define your own key type is the
dependent-map[1] package. It requires implementing some classes for your key
type that encode a proof that key equality entails equality of the type
indices. If the documentation is insufficient feel free to ask me for more
