GHCi, version 7.6.3: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
[1 of 1] Compiling Main             ( street.hs, interpreted )
Ok, modules loaded: Main.
*Main> 
                                                              00000         
          yy                                                  00000         
     xx   yy                                                  00000  |     |
     xx   yyzzzzz   bbbbbbbbbbbbbbbbbbbbbbbbbbbbbb            00000  |     |
     xx   yyzzzzz   bbbbbbbbbbbbbbbbbbbbbbbbbbbbbb            00000  |     |
     xxxxxyyzzzzz   bbbbbbbbbbbbbbbbbbbbbbbbbbbbbb            00000  |     |
     xxxxxyyzzzzz   bbbbbbbbbbbbbbbbbbbbbbbbbbbbbb            00000  |     |
----------------------------------------------------------------------------
*Main> Leaving GHCi.