From dccf2c949c10892b368484c3e85bb2bb14e613e2 Mon Sep 17 00:00:00 2001
From: Gregor Kleen <aethoago@141.li>
Date: Thu, 16 Feb 2017 19:42:50 +0100
Subject: Bruteforce digit calculation

---
 lib/Postdelay/TimeSpec/Utils.hs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

(limited to 'lib/Postdelay/TimeSpec/Utils.hs')

diff --git a/lib/Postdelay/TimeSpec/Utils.hs b/lib/Postdelay/TimeSpec/Utils.hs
index a8c7d4a..fd9c1be 100644
--- a/lib/Postdelay/TimeSpec/Utils.hs
+++ b/lib/Postdelay/TimeSpec/Utils.hs
@@ -22,6 +22,8 @@ import Data.Time.Lens
 import Data.Time.Zones
 
 import Data.Bool
+import Data.Maybe
+import Data.List
 import Data.Foldable
 import Data.Functor
 import Data.Function
@@ -53,7 +55,7 @@ sign = label "sign" $ choice [ char '+' $> id
                              , char '-' $> negateV
                              ]
 
-boundedNatural :: forall s n m. (Show n, Real n, StringParser s m)
+boundedNatural :: forall s n m. (Show n, Ord n, Num n, StringParser s m)
                => Bool -- ^ Require number to be padded with zeroes?
                -> Interval n -> m n
 boundedNatural padded (I.intersection (0 <=..< PosInf) -> bounds) = do
@@ -84,7 +86,7 @@ boundedNatural padded (I.intersection (0 <=..< PosInf) -> bounds) = do
           | otherwise = int
 
     digits :: n -> Int
-    digits = succ . floor . (logBase 10 :: Double -> Double) . realToFrac . abs
+    digits n = succ . fromJust $ findIndex (\(min, max) -> min <= n && n < max) [ (10^i, 10^(succ i)) | i <- ([0..] :: [Int]) ]
 
 boundedRational :: forall s m n. (Show n, RealFrac n, StringParser s m)
                 => Bool -- ^ Require number to be padded with zeroes
-- 
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