(in gmail, I just use reply all). Yeah, that's certainly a valid solution, but ugly like you said. Would a record like this work better for you? data Foo = { root :: Root, oct :: Oct, mode :: Mode } It accomplishes the same thing. Each field can have at most one value, you can update any field, and you can leave any fields uninitialized like this: initFoo = Foo { root = error "root is not initialized", oct = error "oct is not initialized", mode = error "mode is not initialized" } On Wed, May 26, 2010 at 1:35 PM, Tom Jordan <viresh53@gmail.com> wrote:
Sorry that I couldn't respond to the previous thread.. I'm using Gmail and not an email client so I couldn't use the reply button. I'll try to resolve this issue soon !
Thanks Phillip for responding so quickly,
I tried Data.Map first and ran into the issue you mentioned..
I've found a way to get around it, but it's ugly and verbose..
Instead, I'm wondering if there is a way to use the constructors for the "Val" types below, in place of the keys such as:
data Val = Root Root | Oct Oct | Mode Mode deriving (Show, Eq, Ord)
And matching against the constructors, instead of resorting to this:
import IO import qualified Data.Map as Map
type Root = String type Oct = Integer type Mode = Integer
data Key = Root | Oct | Mode deriving (Show, Eq, Ord) data Val = Root_v Root | Oct_v Oct | Mode_v Mode deriving (Show, Eq, Ord)
test = Map.insert Oct (Oct_v 3) . Map.insert Mode (Mode_v 0) . Map.insert Root (Root_v "2") $ Map.empty
main = print test
-- ----> fromList [(Root,Root_v "2"),(Oct,Oct_v 3),(Mode,Mode_v 0)]
Many Thanks,
Tom
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