From 96d094403e343ecf28c1898c9792e4bb1699b58a Mon Sep 17 00:00:00 2001
From: Oleg Grenrus <oleg.grenrus@iki.fi>
Date: Thu, 2 May 2019 23:39:41 +0300
Subject: [PATCH] Comment C, which clarifies why e.g. ReadP is not enough

---
 haddock-api/src/Haddock/Interface/ParseModuleHeader.hs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/haddock-api/src/Haddock/Interface/ParseModuleHeader.hs b/haddock-api/src/Haddock/Interface/ParseModuleHeader.hs
index e4528522..6ac2f186 100644
--- a/haddock-api/src/Haddock/Interface/ParseModuleHeader.hs
+++ b/haddock-api/src/Haddock/Interface/ParseModuleHeader.hs
@@ -86,6 +86,13 @@ parseModuleHeader dflags pkgName str0 =
 -- the value will be "this is a .. description" and the rest will begin
 -- at "The module comment".
 
+-- | 'C' is a 'Char' carrying its column.
+--
+-- This let us make an indentation-aware parser, as we know current indentation.
+-- by looking at the next character in the stream ('curInd').
+--
+-- Thus we can munch all spaces but only not-spaces which are indented.
+--
 data C = C {-# UNPACK #-} !Int Char
 
 newtype P a = P { unP :: [C] -> Maybe ([C], a) }
-- 
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