GHCi, version 7.4.1: 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> 
<interactive>:2:14: Not in scope: `x'

<interactive>:2:23: Not in scope: `y'

<interactive>:2:32: Not in scope: `z'
*Main> Leaving GHCi.