Open type representations and dynamic types https://github.com/emilaxelsson/open-typerep
|Latest on Hackage:||0.6.1|
This package is not currently in any snapshots. If you're interested in using it, we recommend adding it to Stackage Nightly. Doing so will make builds more reliable, and allow stackage.org to host generated Haddocks.
This package uses Data Types à la Carte to provide open type representations and dynamic types/coercions for open type universes.
Example 1 (dynamic types):
type MyUniverse = IntType :+: BoolType hlist :: [Dynamic MyUniverse] hlist = [toDyn True, toDyn (1 :: Int)]
*Main> hlist [True,1]
Note that if we were using
Data.Dynamic, it would just print
Example 2 (dynamically typed addition):
addDyn :: (TypeEq ts ts, PWitness Num ts ts) => Dynamic ts -> Dynamic ts -> Maybe (Dynamic ts) addDyn (Dyn ta a) (Dyn tb b) = do Dict <- typeEq ta tb Dict <- pwit pNum ta return (Dyn ta (a+b))
Data.Dynamic could only do this monomorphically, for one
Num type at a