never executed always true always false

    1 module HelVM.HelMA.Automata.Zot.Parser (
    2   parse,
    3 ) where
    4 
    5 import           HelVM.HelMA.Automata.Zot.Expression
    6 
    7 import qualified Data.Text.Lazy                      as LText
    8 
    9 parse :: LText -> ExpressionList
   10 parse = concatMap parseLine . LText.lines
   11 
   12 parseLine :: LText -> ExpressionList
   13 parseLine = readExpressionList . filter01 . LText.takeWhile (/= '#')
   14 
   15 filter01 :: LText -> LText
   16 filter01 = LText.filter is01
   17 
   18 is01 :: Char -> Bool
   19 is01 c = c == '0' || c == '1'