From 21af9a4051b10e0e41d2941f90539d10584f651d Mon Sep 17 00:00:00 2001
From: Oleg Grenrus <oleg.grenrus@iki.fi>
Date: Thu, 8 Nov 2018 18:36:31 +0200
Subject: [PATCH] Tweak lookupResponseHeader docs

---
 servant/src/Servant/API/ResponseHeaders.hs | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/servant/src/Servant/API/ResponseHeaders.hs b/servant/src/Servant/API/ResponseHeaders.hs
index adcd5694..e5ff1ed9 100644
--- a/servant/src/Servant/API/ResponseHeaders.hs
+++ b/servant/src/Servant/API/ResponseHeaders.hs
@@ -201,18 +201,27 @@ instance {-# OVERLAPPABLE #-} (HasResponseHeader h a rest) => HasResponseHeader
 -- >>> let example2 = addHeader True example1 :: Headers '[Header "1st" Bool, Header "someheader" Int] String
 -- >>> lookupResponseHeader example2 :: ResponseHeader "someheader" Int
 -- Header 5
+--
 -- >>> lookupResponseHeader example2 :: ResponseHeader "1st" Bool
 -- Header True
 --
 -- Usage of this function relies on an explicit type annotation of the header to be looked up.
 -- This can be done with type annotations on the result, or with an explicit type application.
--- e.g.
--- @lookupResponseHeader \@"someheader" example2@
+-- In this example, the type of header value is determined by the type-inference,
+-- we only specify the name of the header:
+--
+-- >>> :set -XTypeApplications
+-- >>> case lookupResponseHeader @"1st" example2 of { Header b -> b ; _ -> False }
+-- True
+--
+-- @since 0.15
+--
 lookupResponseHeader :: (HasResponseHeader h a headers)
   => Headers headers r -> ResponseHeader h a
 lookupResponseHeader = hlistLookupHeader . getHeadersHList
 
 -- $setup
+-- >>> :set -XFlexibleContexts
 -- >>> import Servant.API
 -- >>> import Data.Aeson
 -- >>> import Data.Text