Hello, I've recently run across an odd situation. I have a brand new install of GHC-6.12.1 (just did a fresh install of OSX 10.6), and am reinstalling some libraries. I've run into an unusual problem. I'm not sure if this would be considered a cabal bug or not, but I don't think it's a good situation. data-accessor-template depends upon template-haskell (>=2.2 && <2.4), unless built with the flag -ftemplate_2_4, in which case it depends upon template-haskell 2.4 (appropriate for ghc-6.12.1). The relevant lines of the .cabal file are: Flag template_2_4 description: Adapt to TemplateHaskell version of GHC-6.12 default: False If flag(template_2_4) Hs-Source-Dirs: src-5 Build-Depends: template-haskell >=2.4 && <2.5 Else Hs-Source-Dirs: src-3 Build-Depends: template-haskell >=2.2 && <2.4 I can install data-accessor-template when the template_2_4 flag is used, but then when I try to install a package that depends upon data-accessor-template cabal-install calculates the template-haskell

=2.2 && <2.4 dependency and attempts to fulfill it. Which fails at packedstring (can't find Data.Data in a hidden base package).

I've included output from attempting to install Chart that demonstrates the behavior. Note that even though cabal-install sees data-accessor-template as installed, it attempts to reinstall it. John-Latos-MacBook:packages johnlato$ cabal install -v -O Chart In order, the following would be installed: packedstring-0.1.0.1 (new package) template-haskell-2.3.0.1 (new version) data-accessor-template-0.2.1.3 (reinstall) changes: template-haskell-2.4.0.0 -> 2.3.0.1 Chart-0.12 (new package) This affects everything down the dependency tree, notably Chart, criterion, and yi. I can work around this by specifying a previous version of data-accessor-template, but unfortunately I don't know how to address the real problem. Cheers, John