Learning haskell and trying to use sets

Lakin 2018-03-03 18:19:55.502014 UTC

1 import Data.Set (delete, fromList, showTreeWith)
2 main = do
3 let x = fromList [0..3]
4 print 1
5 print x
6 print 2
7 let x = delete 0 (fromList [0,1,2])
8 print 3
9 print x
10 print 4
11 let x = delete 1 x
12 print 5
13 print x -- What is "test: <<loop>>"
14 print 6 -- Why does this not output