Better fixed precision

1 files changed, 11 insertions, 5 deletions

diff --git a/src/Trivmix.hs b/src/Trivmix.hs
index d95ea46..37ecec6 100644
--- a/src/Trivmix.hs
+++ b/src/Trivmix.hs
@@ -34,6 +34,8 @@ import Data.Char
 import Data.Function
 
 import Control.Monad
+
+import Data.Fixed
   
 import           Data.CaseInsensitive  ( CI )
 import qualified Data.CaseInsensitive as CI
@@ -48,14 +50,18 @@ data Options = Options
 
 data Level = Lin Float | DB Float
 
-fixedPrecision :: (RealFrac a, Num a) => a -> a -> a
-fixedPrecision p x = (fromInteger $ round $ p' * x) / p'
-  where
-    p' = 1 / p
+withPrec :: (Num a, RealFrac a, HasResolution b) => a -> Fixed b
+withPrec x = withResolution $ \p' -> MkFixed $ toInteger $ round $ x * (fromInteger p')
+
+withType :: (p a -> f a) -> f a
+withType f = f undefined
+
+withResolution :: (HasResolution a) => (Integer -> f a) -> f a
+withResolution f = withType (f . resolution)
 
 instance Show Level where
   show (Lin x) = show x
-  show (DB x) = (show $ fixedPrecision 1e-3 x') ++ "dB"
+  show (DB x) = (show $ (withPrec x' :: Milli)) ++ "dB"
     where
       x' = 20 * (logBase 10 x)