1 files changed, 5 insertions, 0 deletions
diff --git a/src/Data.hs b/src/Data.hs
index 4584a53..e951ef2 100644
--- a/src/Data.hs
+++ b/src/Data.hs
@@ -45,6 +45,11 @@ sreplicate (SS n) x = x `SCons` sreplicate n x
 data Nat = Z | S Nat
   deriving (Show, Eq, Ord)
 
+type N0 = Z
+type N1 = S N0
+type N2 = S N1
+type N3 = S N2
+
 data SNat n where
   SZ :: SNat Z
   SS :: SNat n -> SNat (S n)