Perhaps one could have top-level implicit parameters (or top-level contexts in general):
module (?myvar :: IORef Int) => Random where
Hi! I suggested something very similar to this some months ago, syntax and all. Nice to see I'm not the only one thinking along this lines. http://www.mail-archive.com/haskell%40haskell.org/msg14884.html
module Main where import MyMain
-- mymain :: (?myvar :: IORef Int) => IO () -- outside
main = do var <- newIORef 1 -- initialisers in the order you want let ?myvar = var in mymain
By then I also suggest that maybe we could also bind the implicit on import, something like:
module (?par :: Parameter) => A where ...
module B where import A -- simple, ?par unbound import qualified A as Ak where ?par = k -- ?par bound to k import qualified A as Am where ?par = m -- ?par bound to m
Seemed fine as long as the parameters didn't depend on the imported modules. But on hindsight, making an import depend on valued defined in the body of the module is probably quite clumsy, unfortunately (right?). Still,
import qualified A as Ak where ?par = 1 or import qualified A as Ak where ?par = newIORef or even import C(k) import qualified A as Ak where ?par = k
Doesn't sound that bad though. J.A.