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  • Algorithms
    Logic
    Description

    What is the easiest way to check if all elements are equal in a Haskell list? Perhaps something that is safer than using head or tail?

    For instance: 

    allEqual [1,2,3,4] = False 
allEqual [1,1,1,1] = True
    Code 
    module AllEqual where

allEqual :: [Int] -> Bool 
allEqual xs = and $ map (== head xs) (tail xs)
     Test Cases 
    import Test.Hspec
import AllEqual

main = hspec $ do
  describe "All Equal" $ do
    it "Basic tests" $ do      
      allEqual [1,2,3,4] `shouldBe` False
      allEqual [1,1,1,1] `shouldBe` True
    View Run Output