In parsing libraries for Haskell the "parse" function (or its equivalent) typically returns an Either. For instance there's
in Text.Parsec.Prim. This is an example of making invalid state impossible. parse could return a list of all possible parses, with the empty list signifying that parsing failed. But by using an Either, the case of failure can be distinguished as a Left. Haskell will know to treat the Left differently, and if you need an error report, that left can bubble (through multiple Either-returning functions, with some handy do-notation) up to the user without ever invoking an exception to the ordinary control flow.