From 907f362ab59cc03c81f6fbcb41657dad6dd5b15d Mon Sep 17 00:00:00 2001
From: Evan Rutledge Borden <eborden@frontrowed.com>
Date: Sun, 23 Jun 2019 12:06:06 -0500
Subject: [PATCH] Add support for OverloadedLabels

`OverloadedLabels` is a simple enough extension to parse and format. It
is becoming more common with use of `generic-lens`. Since it can be
treated as a `HsVar` its implementation only requires using `docLit`,
along with some marshalling for dealing with `FastString`.
---
 src-literatetests/14-extensions.blt                    | 10 ++++++++++
 .../Haskell/Brittany/Internal/Layouters/Expr.hs        |  6 +++---
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/src-literatetests/14-extensions.blt b/src-literatetests/14-extensions.blt
index e403568..12facda 100644
--- a/src-literatetests/14-extensions.blt
+++ b/src-literatetests/14-extensions.blt
@@ -130,3 +130,13 @@ func = do
   hello
   |]
   pure True
+
+###############################################################################
+## OverloadedLabels
+#test bare label
+{-# LANGUAGE OverloadedLabels #-}
+foo = #bar
+
+#test applied and composed label
+{-# LANGUAGE OverloadedLabels #-}
+foo = #bar . #baz $ fmap #foo xs
diff --git a/src/Language/Haskell/Brittany/Internal/Layouters/Expr.hs b/src/Language/Haskell/Brittany/Internal/Layouters/Expr.hs
index 74a87af..8a499f2 100644
--- a/src/Language/Haskell/Brittany/Internal/Layouters/Expr.hs
+++ b/src/Language/Haskell/Brittany/Internal/Layouters/Expr.hs
@@ -55,9 +55,9 @@ layoutExpr lexpr@(L _ expr) = do
     HsRecFld{} -> do
       -- TODO
       briDocByExactInlineOnly "HsRecFld" lexpr
-    HsOverLabel{} -> do
-      -- TODO
-      briDocByExactInlineOnly "HsOverLabel{}" lexpr
+    HsOverLabel NoExt _reboundFromLabel name ->
+      let label = FastString.unpackFS name
+      in docLit . Text.pack $ '#' : label
     HsIPVar{} -> do
       -- TODO
       briDocByExactInlineOnly "HsOverLabel{}" lexpr