Hi Tom,
my 2 cents here:
it looks like you had an old version of GHC and now, it's a new!
My comments inline:
On Thu, Sep 20, 2012 at 10:18 AM, bucephalus org
Dear fellow Haskellers,
last weak my Linux machine broke down and refused to start again. I bought a new one and installed a fresh new KDE/Linux distribution (Mint/Ubuntu) and it looks and feels awesome. I also installed the Haskell platform via the default GUI installer (mintInstall). But when I try to run my recovered Haskell modules again, strange things happen.
First of all, I have a module that has a line import System and that used to be fine. But now, when I try to load the module in a ghci session, I get a complaint: Could not find module 'System' It is a member of the hidden package 'haskell98-2.0.0.1' ... The same happens if I do a Prelude> :m System What is going on?
Most likely you wanted to import System.IO
Secondly, I have another module that has a data type definition like this data (Show n, Show v, Ord n, Ord v) => Automaton n v = Automaton { nameSet :: Set.Set n, valueSet :: Set.Set v, .... } deriving (Show, Eq, Ord) and that used to work fine, too. But now, I get the complaint Illegal datatype context (use -XDatatypeContexts): (Show n, Show v, Ord n, Ord v) => But when I follow the advice and start the module file with a {-# LANGUAGE DatatypeContexts ... #-} I got the opposite complaint: Warning: -XDatatypeContexts is depracated: It was widely considered a misfeature, and has been removed from the Haskell language. How can I clean this up?
see http://stackoverflow.com/questions/7438600/datatypecontexts-deprecated-in-la... Generally (my fellow haskeller may correct me) I think that's better to put the class constraint on the methods rather than on the type declaration. So it becomes: data Automaton n v = Automaton { nameSet :: Set.Set n, valueSet :: Set.Set v } deriving (Show, Eq, Ord) createAutomaton :: (Show n, Show v, Ord n, Ord v) => n -> v -> Automaton n v createAutomaton n v = Automaton (singleton n) (singleton v) Best, Corentin
Cheers, Tom
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