context-free-art: Generate art from context-free grammars

This is a package candidate release! Here you can preview how this package release will appear once published to the main package index (which can be accomplished via the 'maintain' link below). Please note that once a package has been published to the main package index it cannot be undone! Please consult the package uploading documentation for more information.

[maintain] [Publish]

Create art via context free grammar production rules.

Context free grammar primer

Context free grammars consist of a set of terminal symbols, a set of non-terminal symbols, and production rules that map non-terminals to other symbols.

With a context-free grammar, we can generate strings of terminals that conform to the specified language.

Our language will describe graphics.


import Art.ContextFree.Probabilistic
import Data.List.NonEmpty

-- let's define a Production rule
a = Circle 1

-- this will produce an IO (Maybe Svg) from the blaze-svg package
-- to turn it into a string we can use one of the `blaze-svg` renderers
graphic1 = render $ Circle 1

-- let's create a non-terminal, 'a', which renders a terminal, 'Circle 1'
-- and has an 85% chance of rendering itself, placed to its right
a = NonTerminal $ (100, Circle 1) :| [(85, b)]
b = Mod [Move (2, 0)] a
import Art.ContextFree.Definite
import Data.List.NonEmpty

move = Mod [Move (0, -1.8), Scale 0.8]

armN :: Int -> Symbol
armN 0 = move $ Circle 1
armN n = move $ NonTerminal $
  Circle 1 :| [Mod [Rotate 10] $ armN (n - 1)]

arm :: Symbol
arm = armN 20

spiral = NonTerminal $
  Circle 1 :| [arm, Mod [Rotate 120] arm, Mod [Rotate 240] arm]

The latter produces this graphic:


Change log
Dependencies base (>=4.12 && <5), bifunctors (>=5.5), blaze-markup, blaze-svg (>=0.3.6), random (>=1.1), safe, text (>=1.2), text-show (>=3.8) [details]
License BSD-3-Clause
Author Owen Shepherd
Category Graphics
Home page
Uploaded by 414owen at 2019-10-28T15:59:14Z


[Index] [Quick Jump]


Maintainer's Corner

Package maintainers

For package maintainers and hackage trustees