From 1a449a536e2952e551cd77a8c2077fce9220b36c Mon Sep 17 00:00:00 2001
From: darkf <lw9k123@gmail.com>
Date: Sun, 27 Oct 2013 01:35:32 -0700
Subject: [PATCH] cons pattern "xy"::xs

---
 interp.hs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/interp.hs b/interp.hs
index 07ccb44..8c20b74 100644
--- a/interp.hs
+++ b/interp.hs
@@ -275,6 +275,12 @@ patternBindings (StrP _) _ = Nothing
 
 -- cons on strings
 patternBindings (ConsP x (ListP [])) (StrV (y:[])) = patternBindings x (StrV [y])
+-- "xy":xs pattern
+patternBindings (ConsP (StrP xp) xsp) (StrV str) =
+	let len = length xp in
+	if take len str == xp then -- matches
+		patternBindings xsp $ StrV (drop len str) -- match the rest of the string
+	else Nothing -- no match
 patternBindings (ConsP xp xsp) (StrV (x:xs)) =
 	do
 		xe <- patternBindings xp (StrV [x])