Haskell.

The functional-programming course: types, purity, laziness and type classes. Covers 12 topics.

• Haskell · 1 of 3

  Types and signatures

  What type does ghci give the Haskell literal 1?

  ghci> :type 1

  ANum a => aBEq a => aCReal a => aDOrd a => a

• Haskell · 2 of 3

  Types and signatures

  In GHC 9.6.7 ghci, what does :type flip (-) 1 print?

  AA function Integer -> IntegerBA function Num c => c -> cCA number of type Num c => cDA function Num c => c -> c -> c

• Haskell · 3 of 3

  Types and signatures

  In ghci, length [1,2,3] has type Int while 1 + 2 has type Num a => a. Why is the first result concrete?

  -- GHC 9.6.7, ghci :type. Literals and the arithmetic over them.1                     :: Num a => a1.5                   :: Fractional a => a1 + 2                 :: Num a => a7 / 2                 :: Fractional a => adiv 7 2               :: Integral a => atruncate 3.7          :: Integral b => bfromIntegral (3::Int) :: Num b => blength [1,2,3]        :: Int

  Athe list literal defaults to [Int]Bghci defaults every call resultCits signature returns a fixed typeDcounting forces a strict evaluation