diff options
Diffstat (limited to 'src/Reducer.hs')
| -rw-r--r-- | src/Reducer.hs | 23 |
1 files changed, 10 insertions, 13 deletions
diff --git a/src/Reducer.hs b/src/Reducer.hs index 8823b3c..d9ca557 100644 --- a/src/Reducer.hs +++ b/src/Reducer.hs @@ -9,8 +9,7 @@ import Data.List ( elemIndex ) import Data.Map ( Map ) import qualified Data.Map as Map import Helper -import System.IO.Unsafe ( unsafePerformIO ) -import System.Random ( randomIO ) +import System.Random hiding ( next ) type Store = Map Int Box type Stack = [Redex] @@ -21,22 +20,20 @@ data Rvar = Num Int | Hole data Redex = Rabs Int Redex | Rapp Redex Redex | Rvar Rvar | Rclosure Redex Store | Rcache Box Redex data Conf = Econf Redex Store Stack | Cconf Stack Redex | End --- TODO: unsafePerformIO is very unpure and ugly!! Unfortunately IO seems to --- make this function and therefore the entire reduction strict :/ toRedex :: Expression -> Redex -toRedex = convertWorker [] +toRedex = convertWorker (mkStdGen 42) [] where - convertWorker ns (Abstraction e) = - let v = unsafePerformIO randomIO :: Int - t = convertWorker (v : ns) e + convertWorker g ns (Abstraction e) = + let (v, g') = uniform g :: (Int, StdGen) + t = convertWorker g' (v : ns) e in Rabs v t - convertWorker ns (Application l r) = - let lhs = convertWorker ns l - rhs = convertWorker ns r + convertWorker g ns (Application l r) = + let lhs = convertWorker g ns l + rhs = convertWorker g ns r in Rapp lhs rhs - convertWorker ns (Bruijn i) = + convertWorker _ ns (Bruijn i) = Rvar $ Num (if i < 0 || i >= length ns then i else ns !! i) - convertWorker _ _ = invalidProgramState + convertWorker _ _ _ = invalidProgramState fromRedex :: Redex -> Expression fromRedex = convertWorker [] |