I have just attempted Cabal-izing my program (splitting it into a library and main program as well), and I'm mystified by some problems I am having. First, when I try to build the library I get: [colin@susannah game-tree]$ runhaskell Setup build Preprocessing library game-tree-1.0.0.0... Building game-tree-1.0.0.0... Data/Tree/Game/Negascout.hs:31:0: Unrecognised pragma [1 of 2] Compiling Data.Tree.Game.Tree ( Data/Tree/Game/Tree.hs, dist/build/Data/Tree/Game/Tree.o ) Data/Tree/Game/Tree.hs:1:0: Failed to load interface for `Prelude': it is a member of package base-3.0.3.0, which is hidden That mystifies me. Googling, it appears to be a common error in the past, but none of the reasons apparently apply to my case. Incidentally, Tree.hs imports nothing. It just looks like: -- | Nodes in game trees -- Copyright 2009 Colin Adams -- -- This file is part of game-tree. -- -- Game-tree is free software: you can redistribute it and/or modify -- it under the terms of the GNU General Public License as published by -- the Free Software Foundation, either version 3 of the License, or -- (at your option) any later version. -- Game-tree is distributed in the hope that it will be useful, -- but WITHOUT ANY WARRANTY; without even the implied warranty of -- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -- GNU General Public License for more details. -- You should have received a copy of the GNU General Public License -- along with game-tree. If not, see http://www.gnu.org/licenses/. module Data.Tree.Game.Tree where -- | Nodes in a game search tree class Tree a where -- | Is this a game-terminating node (e.g. checkmate)? is_terminal :: a -> Bool -- | Heuristic value of node node_value :: a -> Int -- | Child nodes in the game tree (positions more deeply searched) children :: a -> [a] So I couldn't build my program using runhaskell, as I couldn't install the library. Instead, i tried ghc --make instead with the -idir option. It looks in the right place, but still doesn't recognise the module: Chasing modules from: *Chu-shogi.hs Generator.hs:27:7: Could not find module `Data.Tree.Game.Tree': locations searched: Data/Tree/Game/Tree.hs Data/Tree/Game/Tree.lhs dirs=../game-tree/Data/Tree/Game/Tree.hs dirs=../game-tree/Data/Tree/Game/Tree.lhs What am I doing wrong? Perhaps Cabal should be named Caballa instead. -- Colin Adams Preston Lancashire