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Feedback requested: A sample implementation of L-systems in Haskell

A while back I published a draft of an article I wrote to explore L-systems, specifically D0L systems, and would very much enjoy any feedback (positive or negative) of what I have written.

A sample implementation of L-systems in Haskell

Primarily, the content which gives me pause is the mathematics revolving morphic words as I have yet to fully grok them in any greater sense than the one that I have used in my implementation.

Please, critique my work and point out any errors.

Kind regards,
Filip Allberg

By filipallberg at 2016-03-26 20:26 | LtU Forum | previous forum topic | next forum topic | other blogs | 3881 reads

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The URL

L-Systems.

By marco at Sat, 2016-03-26 21:03 | login or register to post comments

Monad was Used to Sequence Operations on the Internet

Yeah, nice. But I don't like your last monadic description of L-system. You completely abstracted even over the theory of L-systems to arrive at a solution which doesn't say much more than that a monad can be applied n times. Wrong abstraction. Not my thing.

By marco at Sat, 2016-03-26 21:30 | login or register to post comments

Dude. Hammer, Nail.

Says it more clearly.

data D0L a = D0L { axiom :: [a]
                   , rules :: a -> [a]
                   }

eval :: D0L a -> D0L a
eval (D0L axiom rules) = D0L (concatMap rules axiom) rules

algae :: D0L Char
algae = D0L "A" rules
  where rules 'A' = "AB"
        rules 'B' = "A"

pythagoras :: D0L Char
pythagoras = D0L "0" rules
  where rules '0' = "1[0]0" 
        rules '1' = "11"
        rules '[' = "["
        rules ']' = "]"

main :: IO ()
main = do
  putStrLn "6 generations of algae"
  mapM_ (putStrLn . axiom) . take 6 $ iterate eval algae

  putStrLn ""

  putStrLn "4 generations of Pythagoras tree"
  mapM_ (putStrLn . axiom) . take 4 $ iterate eval pythagoras

The above code works equally well. Still, wouldn't be what I would like, but gets rid of an abstraction you simply don't need.

By marco at Sat, 2016-03-26 23:05 | login or register to post comments

For reference, what would

For reference, what would you prefer?

By filipallberg at Mon, 2016-09-19 18:37 | login or register to post comments

Initially, we identify an

Initially, we identify an approach to represent a particular L-system, and apply the same line of reasoning to represent other such systems.

Thereafter we will abstract away representing a specific L-system to afford ourselves a framework for representing any valid L-system.

Perhaps the framework is a little too big and general? What rules out a definition such as the following:


algae :: D0L Char
algae = D0L "A" rules
where rules 'A' = "AC"
rules 'B' = "A"

By Andrew Moss at Sun, 2016-03-27 08:08 | login or register to post comments