[Haskell-cafe] Ambiguous type variable

[Ben Lippmeier]

Arjun Guha wrote:

> AlphaBeta.hs:1:
>     Ambiguous type variable `v' in the top-level constraint:
>       `Ord v' arising from use of `maxValue' at AlphaBeta.hs:12 


Another person had a similar problem just the other week.. The error 
messages are different, but the problem is the same.

Read the messages in this thread:
http://www.haskell.org//pipermail/haskell-cafe/2004-July/006424.html

Then read
"Type classes with functional dependencies", Mark P. Jones, 2000
You can get the paper at http://www.cse.ogi.edu/~mpj

Ben.