AA-graph.hs

-- AA graph drawer (as an exercise of mapAccum)
-- 2013-09-16 @nfunato
import Data.List (mapAccumL, transpose)
main = plot =<< getContents
plot = mapM_ putStrLn . convert
convert = transpose . makeVstrs . analyze . parse

parse = map cconv . filter (`elem` "RCF")
  where cconv 'R' = (-1, '/' )
        cconv 'C' = ( 0, '_' )
        cconv 'F' = ( 1, '\\')

analyze = mapAccumL f (0,0,0)
  where f (y,ymin,ymax) (d,c) = ((y+d, min y ymin, max y ymax), (y',c))
            where y' = if c=='\\' then y+1 else y

makeVstrs ((_,ymin,ymax),yplots) = map makeVstr yplots
  where makeVstr (y',c) = map (\y -> if y==y' then c else ' ') [ymin..ymax]

test1 = "RCRFCRFFCCRFFRRCRRCCFRFRFF"

{-
*Main> plot test1
                  __
                 /  \/\/\
 _/\_/\        _/        \
/      \__/\  /
            \/
-}