[Gaining a Monad Intuition] Learn why the monad design pattern came into existence #monads #functional-programming #haskell

Evaluator.idr

module IParsec 

interface Source a where
  feed : Nat -> a -> (List Char, a)
  next : a -> (List Char, a)
  next = feed 1

Source String where
  feed x string = let (first, second) = splitAt x $ unpack string in 
    (first, pack second)

Parser : Source s => s -> Type -> Type
Parser s type = s -> List (type, s)

item : Source s => Parser s Char
item = \source => case next source of 
  ([], _) => []
  ([x], rest) => [(x, rest)]

result : Source s => a -> Parser s a
result a = \source => [(a, source)]

zero : Source s => Parser s a
zero = \source => []

Introduction.md

Sample