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Rooted by: TDD Game: sum
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  • Code 
    module Sum (Sum.sum) where

import Prelude hiding (sum)

sum :: (Foldable t) => t Integer -> Integer
sum = foldr (+) 0
     Test Cases 
    module SumSpec (spec) where

import Prelude hiding (sum)
import qualified Prelude as Pre (sum)
import Sum (sum)
import Test.Hspec

spec :: Spec
spec = do
  it "tests" $ do
    Sum.sum [1] `shouldBe` Pre.sum [1]
  it "Empty list" $ do
    Sum.sum [] `shouldBe` Pre.sum []
  it "Different container" $ do
    Sum.sum (Just 1) `shouldBe` Pre.sum (Just 1)
  it "negative numbers" $ do
    Sum.sum [-1] `shouldBe` Pre.sum [-1]
  it "big numbers" $ do
    Sum.sum [18446744073709551615] `shouldBe` Pre.sum [18446744073709551615]
    View Run Output
  • Code
    • module Sum (Sum.sum) where
    • import Prelude hiding (sum)
    • sum :: (Foldable t) => t Integer -> Integer
    • sum xs | null xs = 0 | otherwise = foldr1 (+) xs
    • sum = foldr (+) 0