LOR-contest/Haskell

Вся программа в одном файле.

module Main where

import Data.Map hiding (map, filter, delete, null)
import Data.List
import System.IO

data Point = Point {
                    x:: Int,
                    y:: Int }
             deriving (Eq, Ord)

toUp (Point x y) = Point x (y + 1)
toDown (Point x y) = Point x (y - 1)
toLeft (Point x y) = Point (x + 1) y
toRight (Point x y) = Point (x - 1) y

data World = World
    { sizex:: Int,
      sizey:: Int,
      walls:: [Point],
      items:: [Point],
      player:: Point,
      carry:: Bool
    }

readWorld y [] = World 0 (y - 1) [] [] (Point 0 0) False
readWorld y (line:rest) = readLine (readWorld (y + 1) rest) 1 line
    where
      readLine world x [] = world { sizex = max x (sizex world) }
      readLine world x (cell:rest) =
          readLine readCell (x + 1) rest
              where
                readCell =
                    world {
                           walls = if cell == '#' then point:worldWalls else worldWalls,
                           items = if cell == '.' then point:worldItems else worldItems,
                           player = if cell == '@' then point else (player world) }
                        where
                          point = Point x y
                          worldWalls = walls world
                          worldItems = items world

getWorld = do
  worldStream <- readFile "data"
  return (readWorld 1 $ lines worldStream)

showWorld _ 0 = []
showWorld world y = (showLine (Point (sizex world) y)) : showWorld world (y - 1)
    where
      showLine (Point 0 _) = []
      showLine point = showCell : showLine (toRight point)
          where
            showCell
                | point `elem` (walls world) = '#'
                | point == (player world) = '@'
                | point `elem` (items world) = '.'
                | otherwise = ' '

isValid world point@(Point x y) =
    point `notElem` (walls world) &&
    x>0 && x<=(sizex world) &&
    y>0 && y<=(sizey world)

bringAll world =
    foldr (++) [] (map bringItem $ items world)
    where
      start = player world
      neighbours point = [dir point |
                          dir <- [toUp, toDown, toLeft, toRight],
                          isValid world (dir point) ]
      waveMap [] wave = wave
      waveMap front wave =
          let source = head front
              nb = filter (`notMember` wave) $ neighbours source
              g = wave ! source + 1 in
          waveMap (tail front ++ nb)
                      (foldr
                       (\point wm -> insertWith (\_ n -> n) point g wm)
                       wave nb)
      waveMap' = waveMap [start] (singleton start 0)
      bringItem item = 
          (traceProgram $ reverse itemTrace) ++ ["take"] ++ traceProgram itemTrace ++ ["drop"]
          where
            itemTrace = trace item
            trace item 
               | start == item = [item]
               | otherwise = item : trace nearest
               where
                 nearest = minimumBy genOrder $ neighbours item
                     where
                       findGen p = findWithDefault (waveMap' ! item) p waveMap'
                       genOrder p1 p2 = compare (findGen p1) (findGen p2)
            traceProgram [point] = []
            traceProgram (point:rest) = (command point (head rest)):(traceProgram rest)
                where
                  command (Point x1 y1) (Point x2 y2) =
                      case Point (x2-x1) (y2-y1) of
                        Point 0 1 -> "up"
                        Point 0 (-1) -> "down"
                        Point 1 0 -> "left"
                        Point (-1) 0 -> "right"

getProgram = do
  str <- getLine
  return (words str)

applyProgram program world initial =
    foldl applyCommand world program
    where
      applyCommand world str =
          case str of
            "up" -> step toUp
            "down" -> step toDown
            "left" -> step toLeft
            "right" -> step toRight
            "take" -> grab True delete
            "drop" -> grab False (:)
            "reset" -> initial
            "collect" -> applyProgram (bringAll world) world initial
            otherwise -> world
          where
            current = player world
            step dir
                | isValid world target = world { player = target }
                | otherwise = world
                where
                  target = dir current
            grab carryFlag action
                | carry world == carryFlag = world
                | otherwise = world { carry=carryFlag,
                                      items=action current (items world) }

doRepl world initial = do
  putStr (unlines $ showWorld world (sizey world))
  program <- getProgram
  if null program
    then
      return ()
    else
      doRepl (applyProgram program world initial) initial

main = do
  world <- getWorld
  doRepl world world