QuickCheck NonEmpty String - listOf

Question

i am learning quickcheck(and haskell too), i have de bellow code:

newtype Urls = FN { unFN :: String } deriving Show

instance Arbitrary Urls where
arbitrary = do protocol <- elements ["http://"]
             name <-  listOf $ elements ['a'..'z']
             domain <- elements [".com",".com.br",".net"]
             return (FN (protocol ++ name ++ domain))

My question is about how i can make listOf never return empty(NonEmpty), because now for some data generated I receive string like {unFN = "http://.net"}, simplifying i want that name never be empty

score 5 · Answer 1 · answered Sep 18 '12 at 22:49

5

Use listOf1 instead of listOf.

answered Sep 18 '12 at 22:49

Roman Cheplyaka

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Oh thanks a lot, but this is not a great name for a function I guess :D – Édipo Féderle Sep 18 '12 at 22:52
3

The `1` suffix for non-empty is used in many places, e.g. `foldl1` and `many1`. – hzap Sep 19 '12 at 00:00
True, but is there any particular reason to use 1 ? – Édipo Féderle Sep 19 '12 at 15:49

QuickCheck NonEmpty String - listOf

1 Answers1