[Haskell] Issue about use of WinHugs

Hi, list I'm new to WinHugs, what's wrong with isUpper of my WinHugs? Hugs> filter isUpper "ABCDEfgh" ERROR - Undefined variable "isUpper" Hugs> filter Char.isUpper "ABCDEfgh" ERROR - Undefined qualified variable "Char.isUpper" Hugs> :version -- Hugs Version Sep 2006 Best Regards, bingfeng __

Re: [Haskell] Generic combination of generic types

I'm not familiar with modal logic, but if modalities stack, you might be able to do something like this. -- Garrett Mitchener {-# OPTIONS_GHC -fglasgow-exts #-} module Test where data L a = F | T | Atom Int | Neg (L a) | And (L a) (L a) | Or (L a) (L a) | M (L a) -- the modali