[Haskell-cafe] FGL problem: cannot acces data constructor NodeMap

Immanuel Normann immanuel.normann at googlemail.com
Sat Jul 24 08:20:47 EDT 2010


I have a problem with the data constructor NodeMap
of the graph library fgl- (also fgl-

I cannot access the data constructor NodeMap, as the ghci session shows:

Prelude> :m Data.Graph.Inductive.NodeMap
Prelude Data.Graph.Inductive.NodeMap> :t NodeMap

<interactive>:1:0: Not in scope: data constructor `NodeMap'

However, when I load the source directly it works:

Prelude> :l Data/Graph/Inductive/NodeMap.hs
[1 of 3] Compiling Data.Graph.Inductive.Graph (
Data/Graph/Inductive/Graph.hs, interpreted )
[2 of 3] Compiling Data.Graph.Inductive.Internal.FiniteMap (
Data/Graph/Inductive/Internal/FiniteMap.hs, interpreted )
[3 of 3] Compiling Data.Graph.Inductive.NodeMap (
Data/Graph/Inductive/NodeMap.hs, interpreted )
Ok, modules loaded: Data.Graph.Inductive.Internal.FiniteMap,
Data.Graph.Inductive.Graph, Data.Graph.Inductive.NodeMap.
*Data.Graph.Inductive.NodeMap> :t NodeMap
NodeMap :: (Ord a) => FiniteMap a Node -> Int -> NodeMap a

Why is that so?

Afterall, my purpose is to get access to the map in a NodeMap and finally to
apply lookup to it. But I don't know how to access the map from a NodeMap
(the map selector isn't accessible either).

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.haskell.org/pipermail/haskell-cafe/attachments/20100724/f4b25662/attachment-0001.html

More information about the Haskell-Cafe mailing list