Haskell Chapter 2

-- HC2T1 - Task 1: Checking Types in GHCi
-- Expected Types:
-- 42 :: Int
-- 3.14 :: Double
-- "Haskell" :: String
-- 'Z' :: Char
-- True && False :: Bool

-- HC2T2 - Task 2: Function Type Signatures and Implementations

add :: Int -> Int -> Int
add x y = x + y

isEven :: Int -> Bool
isEven n = n `mod` 2 == 0

concatStrings :: String -> String -> String
concatStrings s1 s2 = s1 ++ s2

-- HC2T3 - Task 3: Immutable Variables

myAge :: Int
myAge = 21

piValue :: Double
piValue = 3.14159

greeting :: String
greeting = "Hello, Haskell!"

isHaskellFun :: Bool
isHaskellFun = True

-- Trying to modify any of these will result in a compilation error, e.g.
-- myAge = 30  -- Uncommenting this line would cause an error

-- HC2T4 - Task 4: Converting Between Infix and Prefix Notations

-- Prefix notation
prefixAdd = (+) 5 3
prefixMul = (*) 10 4
prefixBool = (&&) True False

-- Infix notation
infixAdd = 7 + 2
infixMul = 6 * 5
infixBool = True && False

-- HC2T5 - Task 5: Defining and Using Functions

circleArea :: Float -> Float
circleArea r = pi * r * r

maxOfThree :: Int -> Int -> Int -> Int
maxOfThree a b c = max a (max b c)

-- HC2T6 - Task 6: Understanding Int vs Integer

smallNumber :: Int
smallNumber = 262

bigNumber :: Integer
bigNumber = 2127

-- Try evaluating 2^64 :: Int in GHCi manually:
-- > 2^64 :: Int
-- This may cause an overflow depending on your system.

-- HC2T7 - Task 7: Boolean Expressions

boolAndTrue = True && True     -- True
boolOrFalse = False || False   -- False
boolNotTrue = not False        -- True
boolComparison = 5 > 10        -- False

-- Main function to run some tests
main :: IO ()
main = do
  putStrLn "-- HC2T2 Function Tests --"
  print (add 4 5)
  print (isEven 6)
  print (concatStrings "Hello, " "World!")

  putStrLn "\n-- HC2T3 Immutable Variables --"
  print myAge
  print piValue
  putStrLn greeting
  print isHaskellFun

  putStrLn "\n-- HC2T4 Infix and Prefix --"
  print prefixAdd
  print prefixMul
  print prefixBool
  print infixAdd
  print infixMul
  print infixBool

  putStrLn "\n-- HC2T5 Function Tests --"
  print (circleArea 3.0)
  print (maxOfThree 10 20 15)

  putStrLn "\n-- HC2T6 Int vs Integer --"
  print smallNumber
  print bigNumber
  putStrLn "Try evaluating 2^64 :: Int manually in GHCi to observe overflow behavior."

  putStrLn "\n-- HC2T7 Boolean Expressions --"
  print boolAndTrue
  print boolOrFalse
  print boolNotTrue
  print boolComparison