1 files changed, 20 insertions, 0 deletions
diff --git a/stdlib.slip b/stdlib.slip
index f3c1d47..dcedafc 100644
--- a/stdlib.slip
+++ b/stdlib.slip
@@ -65,3 +65,23 @@
     )
   )
 ))
+
+
+(let left-or
+  (fn (sum def) ((Sum L R) L) L
+    (case sum
+      ((inl x) x)
+      (_ def))
+  )
+)
+
+
+(let right-or
+  (fn (sum def) ((Sum L R) R) R
+    (case sum
+      ((inr x) x)
+      (_ def))
+  )
+)
+
+