A quiet language for loud problems
pure :: a -> f a
(<*>) :: f (a -> b) -> f a -> f bIn Haskell, functions are pure by default. No side effects. No surprises. A function called with the same arguments will always return the same result — a mathematical truth embedded in code.
data Maybe a = Nothing | Just aclick to explore
The type system is your proof assistant. Maybe encodes the possibility of absence directly in the type — no null pointer exceptions, no runtime surprises. The compiler verifies your logic before a single byte executes.
(.) :: (b -> c) -> (a -> b) -> a -> c
f . g = \x -> f (g x)Functions compose like mathematical morphisms. Small, precise functions combine into complex transformations — each piece comprehensible, the whole provably correct.
class Monad m where
return :: a -> m a
(>>=) :: m a -> (a -> m b) -> m bclick to explore
A monad is a design pattern for sequencing computations. It's not about burritos or boxes — it's about composing effects. IO, State, Maybe, List — each monad encapsulates a different computational context while preserving the elegance of pure composition.
fibs = 0 : 1 : zipWith (+) fibs (tail fibs)
take 10 fibs -- [0,1,1,2,3,5,8,13,21,34]Haskell is lazy by default. Values are computed only when needed. Infinite data structures become natural — an infinite list of Fibonacci numbers exists peacefully in memory, yielding values on demand.
Haskell is not a language you learn in a weekend. It is a language that reshapes the way you think about computation. Every function you write becomes a theorem. Every program, a proof.
haskell.day — a quiet meditation on functional purity