instance Monoid Command

1 files changed, 24 insertions, 0 deletions

diff --git a/Main.hs b/Main.hs
index 7e4bd0b..465610d 100644
--- a/Main.hs
+++ b/Main.hs
@@ -116,6 +116,13 @@ data Command
   -- TODO Move Count Motion
   --      Delete Count Register Motion
   --      etc.
+  | Combine Command Command
+  | Nop
+
+instance Monoid Command where
+    mempty = Nop
+    mappend = Combine
+
 
 
 data ExecError
@@ -232,8 +239,25 @@ execCommand (AlertBadInput s) =
 execCommand (UnboundSequence s n) =
     throwError (UnboundSequenceError s n)
 
+execCommand (Combine c1 c2) = do
+    q0 <- get
+
+    ((eSt1, lines1), q1) <- liftIO $ runExecCommand q0 (execCommand c1)
+
+    -- TODO "stack trace"
+    whenLeft eSt1 throwError
+
+    ((eSt2, lines2), q2) <- liftIO $ runExecCommand q1 (execCommand c2)
+
+    -- TODO "stack trace"
+    whenLeft eSt2 throwError
+
+    tell lines1
+    tell lines2
 
+    put q2
 
+execCommand Nop = return ()