Hi all. This is a small library for rendering and combining Unicode box drawing characters with a simple monoidal interface. It is spun out of a text table/box drawing library I began but have not found the time for. It may also be useful for TUI libraries going for a little more fanciness.
It encapsulates the fairly long/tedious job of enumerating what combinations of box drawing characters should look like, using code that I originally wrote with Template Haskell, but then extracted with -ddump-splices to remove the TH dep. The internal representation is as a Word8 bitfield, with 4 bits for up/down/left/right, and 4 bits for style selection.
Tiny demonstration:
>>> mapM_ putStrLn $ map (\x -> let s = show x in s ++ replicate (40 - length s) ' ' ++ " ==> " ++ [render unicode x]) [up,down,left,right,horizontal,vertical,horizontal<>vertical,up<>horizontal,up<>right,right<>down,right<>down<>rounded,right<>down<>double, doubleVert <> horizontal <> up, doubleHoriz <> vertical <> right]
Drawing Light [BUp] ==> ╵
Drawing Light [BDown] ==> ╷
Drawing Light [BLeft] ==> ╴
Drawing Light [BRight] ==> ╶
Drawing Light [BLeft,BRight] ==> ─
Drawing Light [BUp,BDown] ==> │
Drawing Light [BUp,BDown,BLeft,BRight] ==> ┼
Drawing Light [BUp,BLeft,BRight] ==> ┴
Drawing Light [BUp,BRight] ==> └
Drawing Light [BDown,BRight] ==> ┌
Drawing Rounded [BDown,BRight] ==> ╭
Drawing Double [BDown,BRight] ==> ╔
Drawing DoubleVert [BUp,BLeft,BRight] ==> ╨
Drawing DoubleHoriz [BUp,BDown,BRight] ==> ╞