1 files changed, 20 insertions, 0 deletions
diff --git a/lib/either.fnl b/lib/either.fnl
new file mode 100644
index 0000000..24aafca
--- /dev/null
+++ b/lib/either.fnl
@@ -0,0 +1,20 @@
+(local Either {})
+(local Left {})
+(local Right {})
+(setmetatable Right Either)
+(setmetatable Left Either)
+
+(fn Either.new [self x]
+  (local obj { :value (or x {}) })
+  (tset self "__index" self)
+  (setmetatable obj self))
+(fn Either.of [x] (Right:new x))
+
+(fn Right.map [self f] (Either.of (f self.value)))
+(fn Left.map [self f] self)
+
+{
+ : Either
+ : Left
+ : Right
+}