Graphics.Chalkboard.Board

Boards are the principal type for our images. The are conceptually functions from 2D coordinates to values, typically a color.

Common Boards include

• Board Bool -- A masking Board, or region.
• Board RGB -- Color Board
• Board (Alpha RGB) -- A Color Board with alpha (transparency) values.
• Board (Maybe a) -- A Board with binary transparency.
• Board (Maybe Color) -- A Color Board with binary transparency.
• Board Point -- A Board (or field) of Point values.

The Board datatype

data Board a

'''Board''' is our primary data type, an infinite flat surface (or R2 field) of values. Conceptually, Board a = Point -> a.

Instances

Functor Board

Applicative Board

Scale (Board a)

Over c => Over (Board c)

looking up a point on the Board.

lookup :: Board a -> (R, R) -> a

Creating Boards.

coord :: Board Point

coord field or Board, where each point is its own coordinate in R2.

maskFor :: (Point, Point) -> Board Bool

build a rectangle mask or region.

circularMaskFor :: Point -> R -> Board Bool

build a circular mask or region, with a circle of radius R, and center Point.

Translations on a Board.

scale :: Scale c => R -> c -> c

scaleXY :: (R, R) -> Board a -> Board a

A non-overloaded version of scale which takes a independent x and y coordinate.

move :: (R, R) -> Board a -> Board a

move a Board by specified vector.

rotate :: Radian -> Board a -> Board a

rotate the Board.

crop :: Board Bool -> Board a -> Board (Maybe a)

crop crops a Board, based on a masking Board.

class Functor f => Applicative f where

A functor with application.

Instances should satisfy the following laws:

identity

pure id <*> v = v

composition

pure (.) <*> u <*> v <*> w = u <*> (v <*> w)

homomorphism

pure f <*> pure x = pure (f x)

interchange

u <*> pure y = pure ($ y) <*> u

ignore left value

u *> v = pure (const id) <*> u <*> v

ignore right value

u <* v = pure const <*> u <*> v

The Functor instance should satisfy

fmap f x = pure f <*> x

If f is also a Monad, define pure = return and (<*>) = ap.

Minimal complete definition: pure and <*>.

Methods

pure :: a -> f a

Lift a value.

(<*>) :: f (a -> b) -> f a -> f b

Sequential application.

(*>) :: f a -> f b -> f b

Sequence actions, discarding the value of the first argument.

(<*) :: f a -> f b -> f a

Sequence actions, discarding the value of the second argument.

Instances

Applicative []

Applicative IO

Applicative ZipList

Applicative Maybe

Applicative Board

Applicative ((->) a)

Monoid a => Applicative ((,) a)

Monoid m => Applicative (Const m)

Monad m => Applicative (WrappedMonad m)

Arrow a => Applicative (WrappedArrow a b)