1 files changed, 24 insertions, 0 deletions
diff --git a/transfer/lib/nat.tra b/transfer/lib/nat.tra
new file mode 100644
index 000000000..b13a809ed
--- /dev/null
+++ b/transfer/lib/nat.tra
@@ -0,0 +1,24 @@
+import prelude
+
+data Nat : Type where
+	Zero : Nat
+  	Succ : (n:Nat) -> Nat
+
+add_Nat : Add Nat
+add_Nat = rec zero = Zero
+	      plus = natPlus
+
+natPlus : Nat -> Nat -> Nat
+natPlus Zero y = y
+natPlus (Succ x) y = Succ (natPlus x y)
+
+pred : Nat -> Nat
+pred Zero = Zero
+pred (Succ n) = n
+
+natToInt : Nat -> Integer
+natToInt Zero = 0
+natToInt (Succ n) = 1 + natToInt n
+
+intToNat : Integer -> Nat
+intToNat n = if n == 0 then Zero else Succ (intToNat (n-1))