Hi Paul, | I have just downloaded the new Hugs beta. There is a problem with | the supplied ST module - :load ST gives an error, | | ... | Reading file "C:\Data\HugsBeta\Hugs98\lib\exts\ST.hs": | Parsing | ERROR C:\Data\HugsBeta\Hugs98\lib\exts\ST.hs:48 - Syntax error | in type expression (unexpected `.') I suspect you are running Hugs in Haskell 98 mode. As it says in the Hugs manual: "Note that the ST and LazyST libraries cannot be used when the interpreter is running in Haskell 98 mode; the type for runST requires support for rank-2 polymorphism, which is only available in Hugs mode." Try starting the interpreter with the command line option -98 if you want to use the ST library. I know that the error message above isn't as clear as you might hope, but it is also difficult to do better in Haskell 98 mode where "forall" is a perfectly legal type variable name, and not a keyword. All the best, Mark