29 lines
812 B
Haskell
29 lines
812 B
Haskell
module Matrix where
|
|
import Data.List (intercalate)
|
|
|
|
data Mat a = Mat [[a]]
|
|
type Pos = (Int, Int)
|
|
|
|
instance Functor Mat where
|
|
fmap f (Mat m) = Mat ((map . map) f m)
|
|
|
|
instance (Show a) => Show (Mat a) where
|
|
show (Mat m) = concatMap ((++"\n") . intercalate " " . map show) m
|
|
|
|
-- | Safely access a list
|
|
-- [4,1,5,9] ?? 2 == Just 5
|
|
-- [5,7] ?? 3 == Nothing
|
|
(??) :: [a] -> Int -> Maybe a
|
|
xs ?? n | n < 0 = Nothing
|
|
[] ?? _ = Nothing
|
|
(x:_) ?? 0 = Just x
|
|
(_:xs) ?? n = xs ?? (n-1)
|
|
|
|
-- | Create a matrix of indeces of a matrix
|
|
indeces :: Mat a -> Mat Pos
|
|
indeces (Mat m) = Mat [[(x,y) | y <- [0..length (m !! x)-1]] |
|
|
x <- [0..length m-1]]
|
|
|
|
-- | Create a matrix of zeros
|
|
zeros :: Int -> Int -> Mat Int
|
|
zeros x y = Mat (replicate x $ replicate y 0) |