This package provides a monad transformer version of the ST monad.
 .
 Warning! This monad transformer should not be used with monads that can
 contain multiple answers, like the list monad. The reason is that the will be
 duplicated across the different answers and this cause Bad Things to happen
 (such as loss of referential transparency). Safe monads include the monads
 State, Reader, Writer, Maybe and combinations of their corresponding monad
 transformers.
 .
 This package provides the documentation for a library for the Haskell
 programming language.
 See http://www.haskell.org/ for more information on Haskell.