"No module named ... is imported" message is a bit misleading with qualified imports
It seems that the
No module named ... is imported message produced in response to out-of-scope identifiers doesn't account for qualified imports. For instance,
$ ghci GHCi, version 8.2.1: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/ben/.ghci λ> import qualified Data.Maybe as M λ> M.fromJusr <interactive>:2:1: error: Not in scope: ‘M.fromJusr’ Perhaps you meant ‘M.fromJust’ (imported from Data.Maybe) No module named ‘M’ is imported. λ>
I suppose there is the question of whether we consider
M to be a "module" here; I would argue that I imported it and therefore the message is at very least a bit misleading.