Restructure and begin displaying lambdas

app/Main.hs

@@ -1,6 +1,15 @@
 module Main where
 
-import           Props
+import Data.Void
+
+import Props.Lambda.Term
+
+yCombinator :: Term Void String String
+yCombinator = Lambda "f"
+  (App
+    (Lambda "x" (App (Var 1) (App (Var 0) (Var 0))))
+    (Lambda "x" (App (Var 1) (App (Var 0) (Var 0))))
+  )
 
 main :: IO ()
-main = putStrLn helloWorld
+main = print yCombinator