Merge pull request #380 from adamse/pretty-imports

Pretty print imports

TESTS.md

@@ -80,9 +80,35 @@ import qualified MegaModule as M ((>>>), MonadBaseControl, void, MaybeT(..), joi
 
 ```haskell expect
 import qualified MegaModule as M
-       (Either, Maybe(Just, Nothing), MaybeT(..),
-        Monad((>>), (>>=), return), MonadBaseControl, (<<<), (>>>), join,
-        liftIO, void)
+  ( Either
+  , Maybe(Just, Nothing)
+  , MaybeT(..)
+  , Monad((>>), (>>=), return)
+  , MonadBaseControl
+  , (<<<)
+  , (>>>)
+  , join
+  , liftIO
+  , void
+  )
+```
+
+Pretty import specification
+
+```haskell
+import A hiding
+  ( foobarbazqux
+  , foobarbazqux
+  , foobarbazqux
+  , foobarbazqux
+  , foobarbazqux
+  , foobarbazqux
+  , foobarbazqux
+  )
+
+import Name hiding ()
+
+import {-# SOURCE #-} safe qualified Module as M hiding (a, b, c, d, e, f)
 ```
 
 # Declarations
@@ -940,8 +966,7 @@ import B
 ```
 
 ```haskell expect
-import ATooLongList
-       (alpha, beta, delta, epsilon, eta, gamma, theta, zeta)
+import ATooLongList (alpha, beta, delta, epsilon, eta, gamma, theta, zeta)
 import B
 ```
 

src/HIndent/Pretty.hs

@@ -1538,14 +1538,43 @@ instance Pretty ModulePragma where
   prettyInternal = pretty'
 
 instance Pretty ImportDecl where
-  prettyInternal = pretty'
+  prettyInternal (ImportDecl _ name qualified source safe mpkg mas mspec) = do
+    write "import"
+    when source $ write " {-# SOURCE #-}"
+    when safe $ write " safe"
+    when qualified $ write " qualified"
+    case mpkg of
+      Nothing -> return ()
+      Just pkg -> space >> write pkg
+    space
+    pretty name
+    case mas of
+      Nothing -> return ()
+      Just asName -> do
+        space
+        write "as "
+        pretty asName
+    case mspec of
+      Nothing -> return ()
+      Just spec -> pretty spec
 
 instance Pretty ModuleName where
   prettyInternal (ModuleName _ name) =
     write name
 
 instance Pretty ImportSpecList where
-  prettyInternal = pretty'
+  prettyInternal (ImportSpecList _ hiding spec) = do
+    when hiding $ write " hiding"
+    let verVar = do
+          space
+          parens (commas (map pretty spec))
+    let horVar = do
+          newline
+          indentedBlock
+            (do depend (write "( ") (prefixedLined ", " (map pretty spec))
+                newline
+                write ")")
+    verVar `ifFitsOnOneLineOrElse` horVar
 
 instance Pretty ImportSpec where
   prettyInternal = pretty'