Hi, I'm right at the start of learning Haskell, and I decided to jump from reading LYAH to writing a simple real-world program. It's based very closely on https://github.com/haskell-hvr/cassava/blob/master/examples/NamedBasedGeneri... (I removed the bit that constructs the test file, as I already have a file), and I've done "cabal install cassava", first as root, and then when I first go the error, as myself using the sandbox (which didn't change the output). I first tried this with running ghc directly, and then followed the instructions on https://wiki.haskell.org/How_to_write_a_Haskell_program, and all these get the same errors: Main.hs:4:1: error: Could not find module ‘Data.Csv’ Locations searched: Data/Csv.hs Data/Csv.lhs Data/Csv.hsig Data/Csv.lhsig | 4 | import Data.Csv | ^^^^^^^^^^^^^^^ Main.hs:6:1: error: Could not find module ‘Data.Vector’ Perhaps you meant Data.Functor (from base-4.11.1.0) Locations searched: Data/Vector.hs Data/Vector.lhs Data/Vector.hsig Data/Vector.lhsig | 6 | import qualified Data.Vector as V | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ I don't understand the connection between the name "cassava" and "Data/Csv", although looking around in the directories that have been produced, I see that Data/Csv is within the cassava directories. I'd like not only to know how to fix this, but also a pointer for what I should look at to understand what is going on. This is on a Debian system. thanks, __John (completely new to Haskell, experienced in C, Lisp, Python and others, if that helps to pitch the level of answers)