extractThetaUpdaters :: Filter -> [Filter -> (Double -> Double) -> Filter]
extractThetaUpdaters filter = 
  foldr ((++). getUpdater) [] filter
extractThetaUpdaters :: Filter -> [Filter -> (Double -> Double) -> Filter]
extractThetaUpdaters filter = 
  foldr ((++). getUpdater) [] filter
extractThetaUpdaters filter = 
  foldr ((++). getUpdater) [] filter