Add documentation and examples; Add debugging flag; Minor refactors

docs/implementation/bridoc-design.md

@@ -16,12 +16,21 @@ of different syntactical constructs into a raw `BriDoc` value.
 (technically a `BriDocF` value, we'll explain soon.)
 
 The input of this translation is the syntax tree produced by
-GHC/ExactPrint. The ghc api exposes the syntax tree nodes, and
+GHC/ExactPrint. The GHC API exposes the syntax tree nodes, and
 ExactPrint adds certain annotations (e.g. information about
 in-source comments). The main thing that you will be looking
-at here is the ghc api documentation, for example
+at here is the GHC API documentation, for example
 https://downloads.haskell.org/~ghc/8.0.2/docs/html/libraries/ghc-8.0.2/HsDecls.html
 
+Brittany has several flags for dumping intermediate values of the
+transformation process; relevant for the "input" syntax tree are the flags
+`--dump-ast-unknown` and `--dump-ast-full`, where the latter will print the
+whole ast of the input to stderr, the former will only do so for nodes where
+brittany falls back on the ghc-exactprint output (i.e. in those cases where
+we don't transform, but do a mere copy).
+See [this example ast output](output-example-01.md)
+(yeah, raw ASTs are ~~annoying large~~ fun!)
+
 ## Two examples of the process producing raw BriDoc
 
 1. For example, `Brittany.hs` contains the following code (shortened a bit):
@@ -67,6 +76,12 @@ https://downloads.haskell.org/~ghc/8.0.2/docs/html/libraries/ghc-8.0.2/HsDecls.h
   What are the exact semantics of the different `doc..` functions?
   Why do we need to wrap the `BriDoc` constructors behind those smart-constructor thingies?)
   are not explained yet.
+
+  In [this example output](output-example-02.md) the BriDoc tree produced in
+  this fashion is shown for the trivial input `x :: Maybe Int`. Can you spot
+  the `BDAlt` node that matches the above `docAlt` invocation? (hint: the
+  node is used twice, so we can see two identical `BDAlt` nodes.)
+  This leads directly to:
   
 ## Size of BriDoc trees, Sharing and Complexity
 
@@ -78,7 +93,7 @@ the same node.
 This means the number of nodes in the `BriDoc` value we produces in general is
 exponential in the number for syntax nodes of the input.
 
-But we are targeting for linear run-time, right? So what can save us here?
+But we are aiming for linear run-time, right? So what can save us here?
 You might think: We have sharing! For `let x = 3+3; (x, x)` we only have one
 `x` in memory ever. And indeed, we do the same above: `typeDoc1` and `2` are
 used in exactly that manner: Both are referenced once in each of the two
@@ -114,10 +129,32 @@ So.. we already mentioned "memoization" there, right?
    If the `BriDocF` tree is exponential, the transformations will still
    do only linear-amount of "selection work" in order to convert into a
    linear-sized `BriDoc` tree.
-   
+
    This property is the defining one that motivates the BriDoc
    intermediate representation.
 
+Lets have a look at this selection work! We saw at
+[the above example](output-example-02.md) how `x :: Maybe Int` had a
+non-trivial raw `BriDoc` representation, already with two nested `BDAlt`
+nodes and resulting four alternatives. Removing those nodes is the first
+step of the `BriDoc` transformation, and we can
+[observe the output after removing those nodes](output-example-03.md).
+Quite a bit shorter, the tree-printing-algorithm even thinks that it fits
+in a single line now.
+
+We will not go into detail about how this "alt-transformation" (the one doing
+the "selection work" works and what other transformations follow here.
+For this example not much happens; you can see so in the output which you
+probably already noticed in the last example.
+
+But for the "alt-transformation" itself, lets at least consider what it does:
+We traverse the input BriDoc and whenever a `BDAlt` is encountered, one of the
+alternatives is chosen; the other alternatives and the `BDAlt` node itself are
+discarded.
+The choice is made in such a fashion that, well, the final output does not
+contain lines with more than 80 columns but otherwise relatively few newlines.
+Magic! (for now at least.)
+
 ## BriDocF
 
 The `BriDocF f` type encapsulates the idea that each subnode is wrapped
@@ -132,7 +169,8 @@ Lets have a glance at related code/types we have so far:
 -- The pure BriDoc: What we really want, but cannot use everywhere due
 -- to sharing issues.
 -- Isomorphic to `BriDocF Identity`. We still use this type, because
--- then we have to unwrap the `Identities` only in once place.
+-- then we have to unwrap the `Identities` only in once place after reducing
+-- the tree to a non-exponentially-sized one.
 data BriDoc
   = BDEmpty
   | BDLit !Text
@@ -229,4 +267,4 @@ the scenes. For this reason, we will focus on the smart
 constructors in the following, because they define the
 real interface to be used.
 
-You now might have a glance at "bridoc-api.md"
+You now might have a glance at [bridoc-api.md](bridoc-api.md).

docs/implementation/output-example-01.md

@@ -0,0 +1,59 @@
+invocation:
+
+~~~~
+> brittany --dump-ast-full
+~~~~
+
+input (via stdin, remember ctrl-d to end-of-file):
+
+~~~~
+id :: a -> a
+~~~~
+
+output (all but the last line is stderr):
+
+~~~~
+---- ast ----
+A Just (Ann (DP (0,0)) [] [] [((G AnnEofPos),DP (1,0))] Nothing Nothing)
+  HsModule
+    Nothing
+    Nothing
+    []
+    [ A Just (Ann (DP (0,0)) [] [] [((G AnnDcolon),DP (0,1))] Nothing Nothing)
+        SigD
+          TypeSig
+            [ A Just (Ann (DP (0,0)) [] [] [((G AnnVal),DP (0,0))] Nothing Nothing)
+                Unqual {OccName: id}
+            ]
+            HsIB
+              PlaceHolder
+              HsWC
+                PlaceHolder
+                Nothing
+                A Just (Ann (DP (0,1)) [] [] [((G AnnRarrow),DP (0,1))] Nothing Nothing)
+                  HsFunTy
+                    A Just (Ann (DP (0,0)) [] [] [] Nothing Nothing)
+                      HsAppsTy
+                        [ A Just (Ann (DP (0,0)) [] [] [] Nothing Nothing)
+                            HsAppPrefix
+                              A Just (Ann (DP (0,0)) [] [] [] Nothing Nothing)
+                                HsTyVar
+                                  A Just (Ann (DP (0,0)) [] [] [((G AnnVal),DP (0,0))] Nothing Nothing)
+                                    Unqual {OccName: a}
+                        ]
+                    A Just (Ann (DP (0,1)) [] [] [] Nothing Nothing)
+                      HsAppsTy
+                        [ A Just (Ann (DP (0,0)) [] [] [] Nothing Nothing)
+                            HsAppPrefix
+                              A Just (Ann (DP (0,0)) [] [] [] Nothing Nothing)
+                                HsTyVar
+                                  A Just (Ann (DP (0,0)) [] [] [((G AnnVal),DP (0,0))] Nothing Nothing)
+                                    Unqual {OccName: a}
+                        ]
+    ]
+    Nothing
+    Nothing
+----
+id :: a -> a
+~~~~
+

docs/implementation/output-example-02.md

@@ -0,0 +1,46 @@
+invocation:
+
+~~~~
+> brittany --dump-bridoc-raw
+~~~~
+
+input (via stdin, remember ctrl-d to end-of-file):
+
+~~~~
+x :: Maybe Int
+~~~~
+
+output (all but the last line is stderr):
+
+~~~~
+---- bridoc raw ----
+BDAlt
+  [ BDSeq
+      [ BDSeq [BDLit (pack "x"),BDSeparator]
+      , BDSeq [BDLit (pack "::"),BDSeparator]
+      , BDForceSingleline
+          BDAlt
+            [ BDSeq [BDForceSingleline (BDLit (pack "Maybe")),BDLit (pack " "),BDForceSingleline (BDLit (pack "Int"))]
+            , BDPar BrIndentNone (BDLit (pack "Maybe")) (BDLines [BDEnsureIndent BrIndentRegular (BDLit (pack "Int"))])
+            ]
+      ]
+  , BDAddBaseY
+      BrIndentRegular
+      BDPar
+        BrIndentNone
+        BDLit (pack "x")
+        BDCols
+          ColTyOpPrefix
+          [ BDLit (pack ":: ")
+          , BDAddBaseY
+              BrIndentSpecial 3
+              BDAlt
+                [ BDSeq [BDForceSingleline (BDLit (pack "Maybe")),BDLit (pack " "),BDForceSingleline (BDLit (pack "Int"))]
+                , BDPar BrIndentNone (BDLit (pack "Maybe")) (BDLines [BDEnsureIndent BrIndentRegular (BDLit (pack "Int"))])
+                ]
+          ]
+  ]
+----
+x :: Maybe Int
+~~~~
+

docs/implementation/output-example-03.md

@@ -0,0 +1,23 @@
+invocation:
+
+~~~~
+> brittany --dump-bridoc-alt --dump-bridoc-final
+~~~~
+
+input (via stdin, remember ctrl-d to end-of-file):
+
+~~~~
+x :: Maybe Int
+~~~~
+
+output (all but the last line is stderr):
+
+~~~~
+---- bridoc post-alt ----
+BDSeq [BDSeq [BDLit (pack "x"),BDSeparator],BDSeq [BDLit (pack "::"),BDSeparator],BDSeq [BDLit (pack "Maybe"),BDLit (pack " "),BDLit (pack "Int")]]
+---- bridoc final ----
+BDSeq [BDLit (pack "x"),BDSeparator,BDLit (pack "::"),BDSeparator,BDLit (pack "Maybe"),BDLit (pack " "),BDLit (pack "Int")]
+----
+x :: Maybe Int
+~~~~
+

src-brittany/Main.hs

@@ -147,7 +147,8 @@ mainCmdParser helpDesc = do
           -- let out = do
           --       decl <- someDecls
           --       ExactPrint.exactPrint decl anns
-          (errsWarns, outLText) <- if hasCPP
+          let omitCheck = config & _conf_errorHandling .> _econf_omit_output_valid_check .> confUnpack
+          (errsWarns, outLText) <- if hasCPP || omitCheck
             then return $ pPrintModule config anns parsedSource
             else pPrintModuleAndCheck config anns parsedSource
           let customErrOrder LayoutWarning{}            = 0 :: Int

src/Language/Haskell/Brittany/BackendUtils.hs

@@ -49,8 +49,7 @@ import qualified Data.Text.Lazy.Builder as Text.Builder
 import qualified Language.Haskell.GHC.ExactPrint.Types as ExactPrint
 import           Language.Haskell.Brittany.Utils
 
-import           GHC ( GenLocated(L), moduleNameString )
+import           GHC ( Located, GenLocated(L), moduleNameString )
-import           SrcLoc ( SrcSpan )
 
 
 
@@ -505,7 +504,7 @@ layoutWritePriorComments
      , MonadMultiState LayoutState m
      , MonadMultiWriter (Seq String) m
      )
-  => GenLocated SrcSpan ast
+  => Located ast
   -> m ()
 layoutWritePriorComments ast = do
   mAnn <- do
@@ -539,7 +538,7 @@ layoutWritePostComments :: (Data.Data.Data ast,
                                                MonadMultiWriter Text.Builder.Builder m,
                                                MonadMultiState LayoutState m
                                                , MonadMultiWriter (Seq String) m)
-                         => GenLocated SrcSpan ast -> m ()
+                         => Located ast -> m ()
 layoutWritePostComments ast = do
   mAnn <- do
     state <- mGet
@@ -591,7 +590,7 @@ layoutIndentRestorePostComment = do
 --                                                MonadMultiWriter Text.Builder.Builder m,
 --                                                MonadMultiState LayoutState m
 --                                   , MonadMultiWriter (Seq String) m)
---                                 => GenLocated SrcSpan ast -> m ()
+--                                 => Located ast -> m ()
 -- layoutWritePriorCommentsRestore x = do
 --   layoutWritePriorComments x
 --   layoutIndentRestorePostComment
@@ -600,7 +599,7 @@ layoutIndentRestorePostComment = do
 --                                                MonadMultiWriter Text.Builder.Builder m,
 --                                                MonadMultiState LayoutState m
 --                                                , MonadMultiWriter (Seq String) m)
---                                 => GenLocated SrcSpan ast -> m ()
+--                                 => Located ast -> m ()
 -- layoutWritePostCommentsRestore x = do
 --   layoutWritePostComments x
 --   layoutIndentRestorePostComment

src/Language/Haskell/Brittany/Config.hs

@@ -55,6 +55,7 @@ configParser = do
 
   outputOnErrors <- addSimpleBoolFlag "" ["output-on-errors"] (flagHelp $ parDoc "even when there are errors, produce output (or try to to the degree possible")
   wError             <- addSimpleBoolFlag "" ["werror"] (flagHelp $ parDoc "treat warnings as errors")
+  omitValidCheck <- addSimpleBoolFlag "" ["omit-output-check"] (flagHelp $ parDoc "omit checking if the output is syntactically valid; for dev on brittany")
 
   optionsGhc         <- addFlagStringParams
     ""
@@ -94,6 +95,7 @@ configParser = do
       , _econf_Werror                = wrapLast $ falseToNothing wError
       , _econf_CPPMode               = mempty
       , _econf_ExactPrintFallback    = mempty
+      , _econf_omit_output_valid_check = wrapLast $ falseToNothing omitValidCheck
       }
     , _conf_forward       = ForwardOptions
       { _options_ghc = [ optionsGhc & List.unwords & CmdArgs.splitArgs | not $ null optionsGhc ]

src/Language/Haskell/Brittany/Config/Types.hs

@@ -75,6 +75,7 @@ data ErrorHandlingConfigF f = ErrorHandlingConfig
     -- the syntactic validity of the brittany output, at least in theory there
     -- may be cases where the output is syntactically/semantically valid but
     -- has different semantics that the code pre-transformation.
+  , _econf_omit_output_valid_check :: f (Semigroup.Last Bool)
   }
   deriving (Generic)
 
@@ -329,6 +330,7 @@ staticDefaultConfig = Config
     , _econf_Werror                  = coerce False
     , _econf_CPPMode                 = coerce CPPModeAbort
     , _econf_ExactPrintFallback      = coerce ExactPrintFallbackModeInline
+    , _econf_omit_output_valid_check = coerce False
     }
   , _conf_forward       = ForwardOptions
     { _options_ghc = Identity []
@@ -369,12 +371,13 @@ instance CZip LayoutConfigF where
     (f x8 y8)
 
 instance CZip ErrorHandlingConfigF where
-  cZip f (ErrorHandlingConfig x1 x2 x3 x4)
+  cZip f (ErrorHandlingConfig x1 x2 x3 x4 x5)
-         (ErrorHandlingConfig y1 y2 y3 y4) = ErrorHandlingConfig
+         (ErrorHandlingConfig y1 y2 y3 y4 y5) = ErrorHandlingConfig
     (f x1 y1)
     (f x2 y2)
     (f x3 y3)
     (f x4 y4)
+    (f x5 y5)
 
 instance CZip ForwardOptionsF where
   cZip f (ForwardOptions x1)

src/Language/Haskell/Brittany/LayouterBasics.hs

@@ -69,9 +69,8 @@ import Language.Haskell.Brittany.Types
 import Language.Haskell.Brittany.Utils
 
 import           RdrName ( RdrName(..) )
-import           GHC ( runGhc, GenLocated(L), moduleNameString )
+import           GHC ( Located, runGhc, GenLocated(L), moduleNameString )
 import qualified SrcLoc        as GHC
-import           SrcLoc ( SrcSpan )
 import           OccName ( occNameString )
 import           Name ( getOccString )
 import           Module ( moduleName )
@@ -89,7 +88,7 @@ processDefault
      , MonadMultiWriter Text.Builder.Builder m
      , MonadMultiReader ExactPrint.Types.Anns m
      )
-  => GenLocated SrcSpan ast
+  => Located ast
   -> m ()
 processDefault x = do
   anns <- mAsk
@@ -109,7 +108,7 @@ processDefault x = do
 -- syntactic constructs when children are not handled yet.
 briDocByExact
   :: (ExactPrint.Annotate.Annotate ast)
-  => GenLocated SrcSpan ast
+  => Located ast
   -> ToBriDocM BriDocNumbered
 briDocByExact ast = do
   anns <- mAsk
@@ -125,7 +124,7 @@ briDocByExact ast = do
 -- this, e.g. for any top-level declarations.
 briDocByExactNoComment
   :: (ExactPrint.Annotate.Annotate ast)
-  => GenLocated SrcSpan ast
+  => Located ast
   -> ToBriDocM BriDocNumbered
 briDocByExactNoComment ast = do
   anns <- mAsk
@@ -140,7 +139,7 @@ briDocByExactNoComment ast = do
 briDocByExactInlineOnly
   :: (ExactPrint.Annotate.Annotate ast, Data ast)
   => String
-  -> GenLocated SrcSpan ast
+  -> Located ast
   -> ToBriDocM BriDocNumbered
 briDocByExactInlineOnly infoStr ast = do
   anns <- mAsk
@@ -179,7 +178,7 @@ lrdrNameToText (L _ n) = rdrNameToText n
 
 lrdrNameToTextAnn
   :: (MonadMultiReader Config m, MonadMultiReader (Map AnnKey Annotation) m)
-  => GenLocated SrcSpan RdrName
+  => Located RdrName
   -> m Text
 lrdrNameToTextAnn ast@(L _ n) = do
   anns <- mAsk
@@ -201,7 +200,7 @@ lrdrNameToTextAnn ast@(L _ n) = do
 
 lrdrNameToTextAnnTypeEqualityIsSpecial
   :: (MonadMultiReader Config m, MonadMultiReader (Map AnnKey Annotation) m)
-  => GenLocated SrcSpan RdrName
+  => Located RdrName
   -> m Text
 lrdrNameToTextAnnTypeEqualityIsSpecial ast = do
   x <- lrdrNameToTextAnn ast
@@ -271,7 +270,7 @@ allocNodeIndex = do
 -- docLit t = allocateNode $ BDFLit t
 -- 
 -- docExt :: (ExactPrint.Annotate.Annotate ast, MonadMultiState NodeAllocIndex m)
---        => GenLocated SrcSpan ast -> ExactPrint.Types.Anns -> Bool -> m BriDocNumbered
+--        => Located ast -> ExactPrint.Types.Anns -> Bool -> m BriDocNumbered
 -- docExt x anns shouldAddComment = allocateNode $ BDFExternal
 --                   (ExactPrint.Types.mkAnnKey x)
 --                   (foldedAnnKeys x)
@@ -323,7 +322,7 @@ allocNodeIndex = do
 -- 
 -- 
 -- docPostComment :: (Data.Data.Data ast, MonadMultiState NodeAllocIndex m)
---                => GenLocated SrcSpan ast
+--                => Located ast
 --                -> m BriDocNumbered
 --                -> m BriDocNumbered
 -- docPostComment ast bdm = do
@@ -331,7 +330,7 @@ allocNodeIndex = do
 --   allocateNode $ BDFAnnotationPost (ExactPrint.Types.mkAnnKey ast) bd
 -- 
 -- docWrapNode :: ( Data.Data.Data ast, MonadMultiState NodeAllocIndex m)
---             => GenLocated SrcSpan ast
+--             => Located ast
 --             -> m BriDocNumbered
 --             -> m BriDocNumbered
 -- docWrapNode ast bdm = do
@@ -371,7 +370,7 @@ docLit t = allocateNode $ BDFLit t
 
 docExt
   :: (ExactPrint.Annotate.Annotate ast)
-  => GenLocated SrcSpan ast
+  => Located ast
   -> ExactPrint.Types.Anns
   -> Bool
   -> ToBriDocM BriDocNumbered
@@ -389,6 +388,7 @@ docAltFilter = docAlt . map snd . filter fst
 
 
 docSeq :: [ToBriDocM BriDocNumbered] -> ToBriDocM BriDocNumbered
+docSeq [] = docEmpty
 docSeq l = allocateNode . BDFSeq =<< sequence l
 
 docLines :: [ToBriDocM BriDocNumbered] -> ToBriDocM BriDocNumbered
@@ -460,7 +460,7 @@ docParenLSep = appSep $ docLit $ Text.pack "("
 
 docNodeAnnKW
   :: Data.Data.Data ast
-  => GenLocated SrcSpan ast
+  => Located ast
   -> Maybe AnnKeywordId
   -> ToBriDocM BriDocNumbered
   -> ToBriDocM BriDocNumbered
@@ -469,15 +469,15 @@ docNodeAnnKW ast kw bdm =
 
 class DocWrapable a where
   docWrapNode :: ( Data.Data.Data ast)
-              => GenLocated SrcSpan ast
+              => Located ast
               -> ToBriDocM a
               -> ToBriDocM a
   docWrapNodePrior :: ( Data.Data.Data ast)
-                   => GenLocated SrcSpan ast
+                   => Located ast
                    -> ToBriDocM a
                    -> ToBriDocM a
   docWrapNodeRest  :: ( Data.Data.Data ast)
-                   => GenLocated SrcSpan ast
+                   => Located ast
                    -> ToBriDocM a
                    -> ToBriDocM a
 

src/Language/Haskell/Brittany/Layouters/Expr.hs

@@ -16,7 +16,6 @@ import           Language.Haskell.Brittany.LayouterBasics
 
 import           RdrName ( RdrName(..) )
 import           GHC ( runGhc, GenLocated(L), moduleNameString, AnnKeywordId(..) )
-import           SrcLoc ( SrcSpan )
 import           HsSyn
 import           Name
 import qualified FastString

src/Language/Haskell/Brittany/Layouters/Expr.hs-boot

@@ -16,7 +16,6 @@ import           Language.Haskell.Brittany.LayouterBasics
 
 import           RdrName ( RdrName(..) )
 import           GHC ( runGhc, GenLocated(L), moduleNameString )
-import           SrcLoc ( SrcSpan )
 import           HsSyn
 import           Name
 

src/Language/Haskell/Brittany/Layouters/Pattern.hs

@@ -14,8 +14,7 @@ import           Language.Haskell.Brittany.Types
 import           Language.Haskell.Brittany.LayouterBasics
 
 import           RdrName ( RdrName(..) )
-import           GHC ( runGhc, GenLocated(L), moduleNameString )
+import           GHC ( Located, runGhc, GenLocated(L), moduleNameString )
-import           SrcLoc ( SrcSpan )
 import           HsSyn
 import           Name
 import           BasicTypes
@@ -142,7 +141,7 @@ colsWrapPat :: Seq BriDocNumbered -> ToBriDocM BriDocNumbered
 colsWrapPat = docCols ColPatterns . fmap return . Foldable.toList
 
 wrapPatPrepend
-  :: GenLocated SrcSpan (Pat RdrName)
+  :: Located (Pat RdrName)
   -> ToBriDocM BriDocNumbered
   -> ToBriDocM (Seq BriDocNumbered)
 wrapPatPrepend pat prepElem = do
@@ -154,7 +153,7 @@ wrapPatPrepend pat prepElem = do
       return $ x1' Seq.<| xR
 
 wrapPatListy
-  :: [GenLocated SrcSpan (Pat RdrName)]
+  :: [Located (Pat RdrName)]
   -> String
   -> String
   -> ToBriDocM (Seq BriDocNumbered)

src/Language/Haskell/Brittany/Layouters/Stmt.hs

@@ -14,7 +14,6 @@ import           Language.Haskell.Brittany.LayouterBasics
 
 import           RdrName ( RdrName(..) )
 import           GHC ( runGhc, GenLocated(L), moduleNameString )
-import           SrcLoc ( SrcSpan )
 import           HsSyn
 import           Name
 import qualified FastString

src/Language/Haskell/Brittany/Layouters/Stmt.hs-boot

@@ -14,7 +14,6 @@ import           Language.Haskell.Brittany.LayouterBasics
 
 import           RdrName ( RdrName(..) )
 import           GHC ( runGhc, GenLocated(L), moduleNameString )
-import           SrcLoc ( SrcSpan )
 import           HsSyn
 import           Name
 import qualified FastString

src/Language/Haskell/Brittany/Layouters/Type.hs

@@ -16,7 +16,6 @@ import           Language.Haskell.Brittany.LayouterBasics
 import           RdrName ( RdrName(..) )
 import           GHC ( runGhc, GenLocated(L), moduleNameString )
 import           Language.Haskell.GHC.ExactPrint.Types ( mkAnnKey )
-import           SrcLoc ( SrcSpan )
 import           HsSyn
 import           Name
 import           Outputable ( ftext, showSDocUnsafe )

src/Language/Haskell/Brittany/Types.hs

@@ -17,8 +17,7 @@ import qualified Language.Haskell.GHC.ExactPrint as ExactPrint
 import qualified Data.Text.Lazy.Builder as Text.Builder
 
 import           RdrName ( RdrName(..) )
-import           GHC ( runGhc, GenLocated(L), moduleNameString, AnnKeywordId )
+import           GHC ( Located, runGhc, GenLocated(L), moduleNameString, AnnKeywordId )
-import           SrcLoc ( SrcSpan )
 
 import           Language.Haskell.GHC.ExactPrint ( AnnKey, Comment )
 import           Language.Haskell.GHC.ExactPrint.Types ( KeywordId, Anns, DeltaPos, mkAnnKey )
@@ -181,9 +180,9 @@ data BrIndent = BrIndentNone
 
 type ToBriDocM = MultiRWSS.MultiRWS '[Config, Anns] '[[LayoutError], Seq String] '[NodeAllocIndex]
 
-type ToBriDoc (sym :: * -> *) = GenLocated SrcSpan (sym RdrName) -> ToBriDocM BriDocNumbered
+type ToBriDoc (sym :: * -> *) = Located (sym RdrName) -> ToBriDocM BriDocNumbered
-type ToBriDoc' sym            = GenLocated SrcSpan sym           -> ToBriDocM BriDocNumbered
+type ToBriDoc' sym            = Located sym           -> ToBriDocM BriDocNumbered
-type ToBriDocC sym c          = GenLocated SrcSpan sym           -> ToBriDocM c
+type ToBriDocC sym c          = Located sym           -> ToBriDocM c
 
 data DocMultiLine
   = MultiLineNo
@@ -324,6 +323,7 @@ instance Uniplate.Uniplate BriDoc where
 
 newtype NodeAllocIndex = NodeAllocIndex Int
 
+-- TODO: rename to "dropLabels" ?
 unwrapBriDocNumbered :: BriDocNumbered -> BriDoc
 unwrapBriDocNumbered tpl = case snd tpl of
   BDFEmpty                     -> BDEmpty