Pure Functions - Haskell Typing CST Test

Pure Functions — Haskell Code

Demonstrates Haskell's pure functions, pattern matching, and list operations.

-- Define a custom data type
data Shape = Circle Float | Rectangle Float Float

-- Calculate area using pattern matching
area :: Shape -> Float
area (Circle r) = pi * r * r
area (Rectangle w h) = w * h

-- Higher-order functions
quicksort :: (Ord a) => [a] -> [a]
quicksort [] = []
quicksort (x:xs) = 
	let smaller = quicksort [a | a <- xs, a <= x]
		bigger = quicksort [a | a <- xs, a > x]
	in smaller ++ [x] ++ bigger

-- List operations
fibonacci :: [Integer]
fibonacci = 0 : 1 : zipWith (+) fibonacci (tail fibonacci)

-- Main function
main :: IO ()
main = do
	let shapes = [Circle 5.0, Rectangle 3.0 4.0, Circle 2.5]
	let areas = map area shapes

	putStrLn $ "Areas: " ++ show areas
	putStrLn $ "First 10 fibonacci: " ++ show (take 10 fibonacci)
	putStrLn $ "Sorted [3,1,4,1,5,9]: " ++ show (quicksort [3,1,4,1,5,9])

Haskell Language Guide

Haskell is a purely functional, statically typed programming language known for immutability, strong type inference, mathematical precision, and high reliability. It is widely used in finance, compilers, research, distributed systems, and correctness-critical software.

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