// MISSION_BRIEFING.lhs

HASKELL QUEST

A neon-lit data realm where lambdas hunt monads and types are pure.

You are operative QX-7741. Your mission, should you choose to compile it: traverse 42 quests across the algebraic frontier, unlock the IO sectors, and bind the Maybe nebula.

00QUESTS

0000OPERATIVES

0000COMPILES

00% PURE

// SECTOR_02

QUEST GRID

Hexagonal sectors of the algebraic frontier. Hover a node to read intel; click to deploy.

// COMPLETE // ACTIVE // LOCKED

// SECTOR_03

HOLOGRAPHIC TERMINAL

Live challenge harness. Stream input on the left, compile output on the right.

// CHALLENGE_07.txt

> Quest 07 // The Maybe Nebula

Implement safeDiv :: Int -> Int -> Maybe Int such that a division by zero returns Nothing and any other input returns Just the quotient. Bind it through >>= for triple chained division.

// constraints

no error, no undefined
total function, pure
must compile under -Wall

// hints

Reach for do-notation only after the kleisli arrow stops smiling at you.

// editor.hs READY

module Quest07 where

safeDiv :: Int -> Int -> Maybe Int
safeDiv _ 0 = Nothing
safeDiv x y = Just (x `div` y)

chain :: Int -> Int -> Int -> Maybe Int
chain a b c =
  safeDiv a b >>= \r ->
  safeDiv r c

main :: IO ()
main = print (chain 144 12 2)

// stdout will materialize here

// SECTOR_04

OPERATIVE LEADERBOARD

Top compilers in the algebraic frontier. Updated every cycle.

RANK	OPERATIVE	SECTOR	QUESTS	SCORE
01	monad.witch	IO/Maybe	42	99,420
02	lambda_drift	Functor	41	92,108
03	kleisli_kid	Arrow	40	88,776
04	foldr_phantom	List	38	81,202
05	typevar_t	HKT	37	78,944
06	purefn_77	Lambda	36	74,610
07	nullable.io	Maybe	34	70,005
08	applicative_x	Applicative	33	66,318
09	traverse_v	Traversable	31	61,777
10	QX-7741	YOU	07	14,210

HASKELL QUEST

QUEST GRID

Pure Functions

HOLOGRAPHIC TERMINAL

OPERATIVE LEADERBOARD