1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
|
module Fallen.Point
( Point,
Direction(North, South, East, West),
directions,
distance,
stepInDirection,
opposite,
randomPoint,
dirToPoint
) where
import System.Random
type Point = (Int, Int)
data Direction = North | South | East | West deriving (Show)
-- directions :: [Direction]
directions = [North, South, East, West]
-- distance :: Point -> Point -> Int
distance (x1, y1) (x2, y2) = ceiling . sqrt . fromIntegral $ (x1-x2)^2 + (y1-y2)^2
-- stepInDirection :: Point -> Direction -> Point
stepInDirection (x, y) dir = case dir of
North -> (x, y-1)
South -> (x, y+1)
East -> (x+1, y)
West -> (x-1, y)
-- opposite :: Direction -> Direction
opposite dir = case dir of
North -> South
South -> North
East -> West
West -> East
-- randomPoint :: Int -> Int -> Int -> Int -> IO Point
randomPoint minX minY maxX maxY rg = do
let (x,rg1) = randomR (minX, maxX) rg :: (Int,StdGen)
let (y,rg2) = randomR (minY, maxY) rg1 :: (Int,StdGen)
((x,y),rg2)
-- dirToPoint :: Point -> Point -> [Direction]
dirToPoint p1 p2 = horizDirToPoint p1 p2 ++ vertDirToPoint p1 p2 where
horizDirToPoint (x1,y1) (x2,y2) = case compare x1 x2 of
LT -> [East]
EQ -> []
GT -> [West]
vertDirToPoint (x1,y1) (x2,y2) = case compare y1 y2 of
LT -> [North]
EQ -> []
GT -> [South]
instance Eq Direction where
North == North = True
South == South = True
East == East = True
West == West = True
_ == _ = False
|
