{-# LANGUAGE NoMonomorphismRestriction, TupleSections #-}
import Diagrams.Prelude
import Diagrams.Backend.Cairo.CmdLine
axes n = h <> v
where p = fromOffsets . replicate n
h = stroke' with {vertexNames = [map ("x",) [0..n]]} (p unitX)
v = stroke' with {vertexNames = [map ("y",) [0..n]]} (p unitY)
connect n i = withAName ("x",i) $ \x ->
withAName ("y", n - i) $ \y ->
drawConnect [x,y]
where drawConnect = atop . fromVertices
pic n = applyAll (map (connect n) [0..n]) (axes n) # centerXY # lw 0.05
d n = half === rotateBy (1/2) half
where half = rotateBy (1/4) (pic n) ||| pic n
main = defaultMain (pad 1.1 $ d 20 # lc blue)