From 730cf4755596090a214075e05e92d70f3f6ea69e Mon Sep 17 00:00:00 2001
From: Joe Crayne <joe@jerkface.net>
Date: Thu, 4 Jul 2019 17:22:43 -0400
Subject: refactor

---
 Data/OpenPGP.hs | 28 ++++++++++------------------
 1 file changed, 10 insertions(+), 18 deletions(-)

diff --git a/Data/OpenPGP.hs b/Data/OpenPGP.hs
index 0165a97..a297c34 100644
--- a/Data/OpenPGP.hs
+++ b/Data/OpenPGP.hs
@@ -1,4 +1,5 @@
-{-# LANGUAGE CPP #-}
+{-# LANGUAGE CPP           #-}
+{-# LANGUAGE PatternGuards #-}
 -- | Main implementation of the OpenPGP message format <http://tools.ietf.org/html/rfc4880>
 --
 -- The recommended way to import this module is:
@@ -1051,23 +1052,14 @@ signatures (Message ps) =
 
 -- TODO: UserAttribute
 paired_sigs :: Maybe Packet -> [Packet] -> [SignatureOver]
-paired_sigs _ [] = []
-paired_sigs _ (p@(PublicKeyPacket {is_subkey = False}):ps) =
-        KeySignature p (takeWhile isSignaturePacket ps) :
-        paired_sigs (Just p) (dropWhile isSignaturePacket ps)
-paired_sigs _ (p@(SecretKeyPacket {is_subkey = False}):ps) =
-        KeySignature p (takeWhile isSignaturePacket ps) :
-        paired_sigs (Just p) (dropWhile isSignaturePacket ps)
-paired_sigs (Just k) (p@(PublicKeyPacket {is_subkey = True}):ps) =
-        SubkeySignature k p (takeWhile isSignaturePacket ps) :
-        paired_sigs (Just k) (dropWhile isSignaturePacket ps)
-paired_sigs (Just k) (p@(SecretKeyPacket {is_subkey = True}):ps) =
-        SubkeySignature k p (takeWhile isSignaturePacket ps) :
-        paired_sigs (Just k) (dropWhile isSignaturePacket ps)
-paired_sigs (Just k) (p@(UserIDPacket {}):ps) =
-        CertificationSignature k p (takeWhile isSignaturePacket ps) :
-        paired_sigs (Just k) (dropWhile isSignaturePacket ps)
-paired_sigs k (_:ps) = paired_sigs k ps
+paired_sigs _  []     = []
+paired_sigs mk (p:ps) = ($ span isSignaturePacket ps) $ case p of
+  PublicKeyPacket {is_subkey = False} -> \(ss,qs) -> KeySignature p ss : paired_sigs (Just p) qs
+  SecretKeyPacket {is_subkey = False} -> \(ss,qs) -> KeySignature p ss : paired_sigs (Just p) qs
+  PublicKeyPacket {is_subkey = True} | Just k <- mk -> \(ss,qs) -> SubkeySignature k p ss : paired_sigs mk qs
+  SecretKeyPacket {is_subkey = True} | Just k <- mk -> \(ss,qs) -> SubkeySignature k p ss : paired_sigs mk qs
+  UserIDPacket {} | Just k <- mk -> \(ss,qs) -> CertificationSignature k p ss : paired_sigs mk qs
+  _ -> \_ -> paired_sigs mk ps
 
 -- | <http://tools.ietf.org/html/rfc4880#section-3.2>
 newtype MPI = MPI Integer deriving (Show, Read, Eq, Ord)
-- 
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