Chapter 3 has an example that read "4" produces an "ambiguous type variable" error. However, this is not the case anymore, since GHCi disables the MonomorphismRestriction, it now throws a "no parse" exception. The problem is that this is used to explain how to specify a type with an explicit type annotation.

I think the easiest solution would be to simply put the definition in a file. Can you think of a better solution?