Relax qualified import syntax

Problem

Case 1.

import Data.HashMap (HashMap)
import qualified Data.HashMap as HashMap
import Data.Map (Map)
import qualified Data.Map as Map
import Data.Set (Set)
import qualified Data.Set as Set
import Data.Text (Text)
import qualified Data.Text as Text

Module names start in different columns, so the user cannot search it without help of tools, so the code is unreadable.

Case 2.

import           Data.HashMap (HashMap)
import qualified Data.HashMap as HashMap
import           Data.Map (Map)
import qualified Data.Map as Map
import           Data.Set (Set)
import qualified Data.Set as Set
import           Data.Text (Text)
import qualified Data.Text as Text

Too many space used, too less space left for imported items list, too hard to maintain without special tools.

Proposal

Allow to write qualified keyword after module name:

import Data.HashMap (HashMap)
import Data.HashMap qualified as HashMap
import Data.Map (Map)
import Data.Map qualified as Map
import Data.Set (Set)
import Data.Set qualified as Set
import Data.Text (Text)
import Data.Text qualified as Text

All the problems solved!

This proposal looks a little like ShorterImportSyntax and #10478, but differs from them in such ways:

1. It doesn't actually make imports shorter in visible symbols, only in lines used (in case of very long imported items list), a little.
2. It doesn't introduce new syntax constructions looking like existing but doing other things.
3. It is easy to implement and understand.
4. It looks more natural from the point of view of English language.

Trac metadata

Trac field	Value
Version	8.0.1
Type	FeatureRequest
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Parser)
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture

changed weight to 5

added Tfeature request Trac import parser labels

While this is a fine idea, I think the best place to have this discussion is as a GHC Proposal. See https://github.com/ghc-proposals/ghc-proposals. There, the community can weigh in on pros and cons of this proposal. If the community (and the GHC Committee) accept this request, then we can use a Trac ticket to track implementation.

Thanks for posting!

https://github.com/ghc-proposals/ghc-proposals/pull/21

added Pnormal label