于 11-8-23 下午11:37, Ivan Lazar Miljenovic 写道:
It might not be what_you_ want, but it might be what others want. If you're concerned with efficiency, then wouldn't you use length rather than genericLength?
length is identical to genericLength in ListLike except type signature. but still, import Data.Number import Data.List import qualified Data.ListLike as L (3 :: Natural) < genericLength [1..] (work) (3 :: Natural) < L.genericLength [1..] (non-terminating) If you want laziness, L.genericLength should be defined like this L.genericLength [] = 0 L.genericLength (_:l) = 1 + L.genericLength l the genericLength used in ListLike package used tail recursion while non-strict. and also, a strict length is still needed (currently, length is identical to genericLength) Thank you bob