Data.Grid

data Grid a

A grid is represented a plain 1D array. It is saved there row by row, starting from the top. Functions in this module take 2D coordinates, but translate them interally to 1D index into the array.

Constructors

• Grid (Array a) { height :: Int, width :: Int }

Instances

• Functor Grid
• FunctorWithIndex Coordinates Grid
• Foldable Grid

enumerate :: forall a. Grid a -> Array (Tuple Coordinates a)

Return the elements of the grid in a flat array, within a tuple containing their original 2D coordinates.

differencesFrom :: forall a. Eq a => Grid a -> Grid a -> Array (Tuple Coordinates a)

Return an array of elements and their coordinates where the two supplied grids differ. If the grids have different dimensions, return all of the elements from the first grid.

updateAt :: forall a. Coordinates -> a -> Grid a -> Maybe (Grid a)

Change the element at the specified index, creating a new grid, or returning Nothing if the index is out of bounds.

modifyAt :: forall a. Coordinates -> (a -> a) -> Grid a -> Maybe (Grid a)

Apply a function to the element at the specified index, creating a new grid, or returning Nothing if the index is out of bounds.

updateAt' :: forall a. Coordinates -> a -> Grid a -> Grid a

Change the element at the specified index, creating a new grid, or don't do anything when the index is out of bounds.

modifyAt' :: forall a. Coordinates -> (a -> a) -> Grid a -> Grid a

Change the element at the specified index, creating a new grid, or don't do anything when the index is out of bounds.

index :: forall a. Grid a -> Coordinates -> Maybe a

This function provides a safe way to read a value at a particular index from a grid. The position { x: 0, y: 0 } is in the top left corner of the grid.

sentence = Grid.fromFoldable 2 2 [ "Hello", "World", "Guys", "!" ]

index sentence { x:0, y:0 } = Just "Hello"
index sentence { x:2, y:0 } = Nothing

replicate :: forall a. Int -> Int -> a -> Grid a

Fill a grid of size width x height with the value a. The value is the same in all of the cells in the grid.

type Coordinates = { x :: Int, y :: Int }

A helper type representing a point on a grid.

Instances

• FunctorWithIndex Coordinates Grid

fromFoldable :: forall f a. Foldable f => Int -> Int -> f a -> Maybe (Grid a)

Create a Grid of the given width and height from any Foldable, like arrays and lists. If the number of elements in array isn't exactly equal to width * height — in other words, there are too many or too few elements — return Nothing.&.

construct :: forall a. Int -> Int -> (Coordinates -> a) -> Grid a

Create a grid of size width x height filled with values returned by a (Coordinates -> a) function. The funcion gets called on every coordinate in the grid and the value it returns is used to fill that specific position. The smallest coordinate is { x: 0, y: 0 } in the upper-left corner of the grid.

It is possible to implement replicate with the help of construct:

replicate w h value = Grid.construct w h (\_ -> value)

For example, Grid.construct 3 3 (\{x, y} -> (x - y) == 0) would create the following grid

true  false false
false true  false
false false true

constructM :: forall m a. Monad m => Int -> Int -> (Coordinates -> m a) -> m (Grid a)