A holographic chronicle of functional programming. Scroll to descend.
A purely functional programming language where every computation is an expression, and every function is a black box that transforms inputs to outputs without side effects. Think of it as mathematics in executable form.
Functions that always return the same output for the same input, with no hidden dependencies or state mutations. Like mathematical functions—reliable, predictable, composable.
add :: Int -> Int -> Int
add x y = x + y
Haskell's type system is like a prism—a single beam of light (your code) passes through, and the type checker reveals its full spectrum of composition, catching errors before runtime.
greet :: String -> String
greet name = "Hello, " ++ name
Monads let you sequence computations while preserving purity. They are the escape hatch for handling side effects (I/O, state, errors) in a controlled, compositional way.
do
putStrLn "Name?"
name <- getLine
putStrLn ("Hello, " ++ name)
Rather than imperative conditionals, Haskell lets you destructure data and branch based on its shape. It's like sorting specimens in a naturalist's collection—each pattern reveals a different case.
factorial :: Int -> Int
factorial 0 = 1
factorial n = n * factorial (n - 1)
Code is not executed until its result is needed. This creates ripples—effects that propagate from the point of demand outward—allowing for elegant handling of infinite data structures and efficient computation.
take 5 [1..] -- Infinite list, but only 5 needed
-- Result: [1, 2, 3, 4, 5]
In Haskell, you build complex behavior by composing simple, pure functions. Each function is a lens through which to view your problem domain—stack them and see the whole picture emerge.
process = filter (> 5) . map (* 2)
result = process [1, 2, 3, 4, 5, 6]