Mandelbrot.hs

{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE QuasiQuotes #-}

module PGExtras.Queries.Mandelbrot (mandelbrotSQL, displayMandelbrot) where

import PGExtras.Helpers (maybeText)
import Database.PostgreSQL.Simple
import Text.RawString.QQ
import qualified Data.Text as Text
import Control.Monad (forM_)
import Data.List (intercalate)

mandelbrotSQL :: Query
mandelbrotSQL = [r|WITH RECURSIVE Z(IX, IY, CX, CY, X, Y, I) AS (

    SELECT IX, IY, X::float, Y::float, X::float, Y::float, 0
    FROM (select -2.2 + 0.031 * i, i from generate_series(0,101) as i) as xgen(x,ix),
         (select -1.5 + 0.031 * i, i from generate_series(0,101) as i) as ygen(y,iy)
    UNION ALL
    SELECT IX, IY, CX, CY, X * X - Y * Y + CX AS X, Y * X * 2 + CY, I + 1
    FROM Z
    WHERE X * X + Y * Y < 16::float
    AND I < 100
    )
SELECT array_to_string(array_agg(SUBSTRING(' .,,,-----++++%%%%@@@@#### ', LEAST(GREATEST(I,1),27), 1)),''), 't' as t
FROM (
      SELECT IX, IY, MAX(I) AS I
      FROM Z
      GROUP BY IY, IX
      ORDER BY IY, IX
     ) AS ZT
GROUP BY IY
ORDER BY IY;|]

displayMandelbrot :: [(Maybe Text.Text, Maybe Text.Text)] -> IO ()
displayMandelbrot rows = do
  putStrLn $ description
  putStrLn $ intercalate " | " tableHeaders
  forM_ rows $ \(arg1, _) ->
    putStrLn $ maybeText(arg1)

description :: [Char]
description = "The mandelbrot set"

tableHeaders :: [[Char]]
tableHeaders = ["name", "ratio"]