converting type-level natural numbers to data-level

Am 15.03.2014 18:13, schrieb adam vogt:

http://www.haskell.org/ghc/docs/7.8.1-rc2/html/users_guide/syntax-extns.html... is the trick

Great, this works! Now I run into the next problem: How can I convert a type-level natural number into a data-level number? The Trac-Wiki mentions singletons: https://ghc.haskell.org/trac/ghc/wiki/TypeNats/Basics and the base package of GHC-7.6 exports the Sing class: http://hackage.haskell.org/package/base-4.6.0.1/docs/GHC-TypeLits.html but it seems to have gone in GHC-7.8. :-(