When creating a Haskell project using Haste, it’s not all that uncommon to want that project – or at least parts of it – to be buildable with vanilla GHC as well. Considering that Haste.App, which is shipped with the standard Haste distribution, more or less requires this functionality to work at all, this is quite a reasonable requirement.
Since Cabal (or stack if you want to be all cool and up to date and stuff) is the build system for Haskell projects, you probably have a
.cabal file for your project:
author: Jane Doe
base >= 4.8 && < 4.9,
haste-lib >= 0.5 && < 0.6
Your application builds just fine when using
haste-cabal, but when you try to build it using vanilla
cabal, you get the following message:
cabal: At least the following dependencies are missing:
That’s not good! What really went wrong here, and how can we fix it?