`pipes-zlib` can be fixed with a simple patch on the upper bound. This has already been fixed in the `master` branch of `pipes-zlib` . I don't know when Renzo plans to upload the latest `pipes-zlib` to Hackage but I've copied him on this.
Clint, Gabriel, All,
Thanks for reporting this to me. I've pushed `pipes-zlib-0.3.1` to hackage with the new upper bound.
The reason I hadn't published this until now is that I wanted to fix this issue in the new release, but I guess it'll have to wait a couple of hours more: