From 655865d883908b7a1a80385d064b93394ddca11d Mon Sep 17 00:00:00 2001
From: Marcin Szamotulski <mszamot@gmail.com>
Date: Sat, 6 May 2017 19:41:08 +0200
Subject: [PATCH] optionalMatch - matching optional path parts

---
 src/Routing/Match.purs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/Routing/Match.purs b/src/Routing/Match.purs
index 8c4736e..7b74992 100644
--- a/src/Routing/Match.purs
+++ b/src/Routing/Match.purs
@@ -176,3 +176,12 @@ eitherMatch (Match r2eab) = Match $ \r ->
     case eit of
       Left _ -> invalid $ free $ Fail "Nested check failed"
       Right res -> pure $ Tuple rs res
+
+-- | useful for matching optional params at the end of a path
+-- | ```
+-- | optParams = maybe M.empty id <$> optionalMatch params <* end
+-- | runMatch (lit "path" *> optParams) (parse id "path/?a=1")
+-- | -- (Right (fromFoldable [(Tuple "a" "1")]))
+-- | ```
+optionalMatch :: forall a. Match a -> Match (Maybe a)
+optionalMatch (Match fn) = Match (\route -> unV (const $ pure (Tuple route Nothing)) (pure <<< map Just) $ fn route)