diff --git a/README.md b/README.md
index 26953fb..f08be1c 100644
--- a/README.md
+++ b/README.md
@@ -2,27 +2,30 @@
 
 ## Introduction
 
-tricu (pronounced like "tree-shoe") is a "micro-language" that [I'm](https://eversole.co) working on to investigate [Tree Calculus](https://github.com/barry-jay-personal/typed_tree_calculus/blob/main/typed_program_analysis.pdf).
+tricu (pronounced like the words "tree-shoe" in English) is a language that [I'm](https://eversole.co) working on to investigate [Tree Calculus](https://github.com/barry-jay-personal/typed_tree_calculus/blob/main/typed_program_analysis.pdf).
 
-tricu [means tree in Lojban](https://en.wiktionary.org/wiki/Appendix:Lojban/tricu). This project was named "sapling" until I discovered the name was already being used for other projects in programming language development.
+tricu is the word for "tree" in Lojban (`(x1) is a tree of species/cultivar (x2)`). This project was named "sapling" until I discovered the name is already being used for other (completely unrelated) programming language development projects.
 
-tricu offers a minimal amount of syntax sugar yet provides a complete and intuitive programming environment. tricu offers:
+tricu offers minimal syntax sugar yet manages to provide a complete, intuitive, and familiar programming environment. There is great power in simplicity. tricu offers:
 
-- `t` operator behaving by the rules of Tree Calculus
-- Function ("variable") definitions
-- Lambda abstractions
-- List, Number, and String literals
+1. `t` operator behaving by the rules of Tree Calculus
+1. Function definitions/assignments
+1. Lambda abstractions eliminated to Tree Calculus forms
+1. List, Number, and String literals
+1. Parentheses intuitively grouping function application
+
+These basic features move us cleanly out of the [turing tarpit](https://en.wikipedia.org/wiki/Turing_tarpit) territory that you may find yourself in if you try working only with the `t` operator. 
 
 ## What does it look like?
 
 ```
 -- Anything after `--` on a line is a comment
--- We can define functions or "variables" as tree calculus values
+-- We can define functions or "variables" as Tree Calculus values
 false = t 
 _ = t
 true = t t
--- We can define functions as lambda expressions that are eliminated to tree
--- calculus terms.
+-- We can define functions as lambda expressions that are eliminated to Tree
+-- Calculus terms.
 id = (\a : a) -- `id` evaluates to the TC form of: t (t (t t)) t
 triage = (\a b c : t (t a b) c)
 -- Intensionality! We can inspect program structure, not just inputs/outputs:
diff --git a/src/Library.hs b/src/Library.hs
index 57fe0a9..09c9df2 100644
--- a/src/Library.hs
+++ b/src/Library.hs
@@ -30,14 +30,13 @@ library = evalTricu Map.empty $ parseTricu $ unlines
   , "matchBool = (\\ot of : triage of (\\_ : ot) (\\_ _ : ot))"
   , "matchList = (\\oe oc : triage oe _ oc)"
   , "matchPair = (\\op : triage _ _ op)"
+  , "not = matchBool false true"
   , "and = matchBool id (\\z : false)"
   , "if = (\\cond then else : t (t else (t t then)) t cond)"
-  , "test = triage \"leaf\" (\\z : \"stem\") (\\a b : \"fork\")"
+  , "test = triage \"Leaf\" (\\z : \"Stem\") (\\a b : \"Fork\")"
   , "emptyList = matchList true (\\y z : false)"
-  , "nonEmptyList = matchList false (\\y z : true)"
   , "head = matchList t (\\hd tl : hd)"
   , "tail = matchList t (\\hd tl : tl)"
-  , "isLeaf = (\\_ : triage true false false)"
   , "listConcat = y (\\self : matchList (\\k : k) (\\h r k : pair h (self r k)))"
   , "lAnd = triage (\\x : false) (\\_ x : x) (\\_ _ x : x)"
   , "lOr = triage (\\x : x) (\\_ _ : true) (\\_ _ x : true)"
diff --git a/src/Main.hs b/src/Main.hs
index 79e6db1..b3434c8 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -12,7 +12,7 @@ import Text.Megaparsec (runParser)
 
 main :: IO ()
 main = do
-  putStrLn "Welcome to the Tricu Interpreter"
+  putStrLn "Welcome to the tricu Interpreter"
   putStrLn "You can exit at any time by typing and entering: "
   putStrLn ":_exit"
   repl library
diff --git a/src/REPL.hs b/src/REPL.hs
index 096ddf5..3a601fd 100644
--- a/src/REPL.hs
+++ b/src/REPL.hs
@@ -28,7 +28,7 @@ repl env = runInputT defaultSettings (loop env)
           case Map.lookup "__result" newEnv of
             Just r -> do
               outputStrLn $ "tricu > " ++ show r
-              outputStrLn $ "DECODE -: " ++ decodeResult r
+              outputStrLn $ "DECODE -: \"" ++ decodeResult r ++ "\""
             Nothing -> return ()
           loop newEnv
 
@@ -36,7 +36,7 @@ decodeResult :: T -> String
 decodeResult tc = case toNumber tc of
   Right num -> show num
   Left _ -> case toString tc of
-    Right str -> "\"" ++ str ++ "\""
+    Right str -> str
     Left _ -> case toList tc of
       Right list -> "[" ++ intercalate ", " (map decodeResult list) ++ "]"
       Left _ -> ""
diff --git a/test/Spec.hs b/test/Spec.hs
index b59647b..c182dd8 100644
--- a/test/Spec.hs
+++ b/test/Spec.hs
@@ -4,6 +4,7 @@ import Eval
 import Lexer
 import Library
 import Parser
+import REPL
 import Research
 import Control.Exception (evaluate, try, SomeException)
 import Test.Tasty
@@ -27,6 +28,7 @@ tests = testGroup "Tricu Tests"
   , integrationTests
   , evaluationTests
   , lambdaEvalTests
+  , libraryTests
   , propertyTests
   ]
 
@@ -67,12 +69,12 @@ lexerTests = testGroup "Lexer Tests"
 
 parserTests :: TestTree
 parserTests = testGroup "Parser Tests"
-  [ --testCase "Error when parsing incomplete definitions" $ do
-    --  let input = lexTricu "x = "
-    --  case (runParser parseExpression "" input) of
-    --    Left _ -> return ()
-    --    Right _ -> assertFailure "Expected failure on invalid input"
-  testCase "Error when assigning a value to T" $ do
+  [-- testCase "Error when parsing incomplete definitions" $ do
+   --   let input = lexTricu "x = "
+   --   case (runParser parseExpression "" input) of
+   --     Left _ -> return ()
+   --     Right _ -> assertFailure "Expected failure on invalid input"
+    testCase "Error when assigning a value to T" $ do
       let input = lexTricu "t = x"
       case (runParser parseExpression "" input) of
         Left _ -> return ()
@@ -222,30 +224,6 @@ evaluationTests = testGroup "Evaluation Tests"
       let input = "x = (\\a : a)\nx " ++ not
           env = evalTricu Map.empty (parseTricu input)
       result env @?= Fork (Fork (Stem Leaf) (Fork Leaf Leaf)) Leaf
-    , testCase "Constant function matches" $ do
-      let input = "k = (\\a b : a)\nk (t t) t"
-          env = evalTricu Map.empty (parseTricu input)
-      result env @?= Stem Leaf
-   , testCase "Boolean AND_ TF" $ do
-      let input = "and (t t) (t)"
-          env = evalTricu library (parseTricu input)
-      result env @?= Leaf
-   , testCase "Boolean AND_ FT" $ do
-      let input = "and (t) (t t)"
-          env = evalTricu library (parseTricu input)
-      result env @?= Leaf
-   , testCase "Boolean AND_ FF" $ do
-      let input = "and (t) (t)"
-          env = evalTricu library (parseTricu input)
-      result env @?= Leaf
-    , testCase "Boolean AND_ TT" $ do
-      let input = "and (t t) (t t)"
-          env = evalTricu library (parseTricu input)
-      result env @?= Stem Leaf
-    , testCase "Verifying Equality" $ do
-      let input = "equal (t t t) (t t t)"
-          env = evalTricu library (parseTricu input)
-      result env @?= Stem Leaf
   ]
 
 lambdaEvalTests :: TestTree
@@ -309,6 +287,98 @@ lambdaEvalTests = testGroup "Lambda Evaluation Tests"
         runTricu input @?= "Fork Leaf (Fork (Stem Leaf) Leaf)"
   ]
 
+libraryTests :: TestTree
+libraryTests = testGroup "Library Tests"
+  [ testCase "K combinator 1" $ do
+      let input = "k (t) (t t)"
+          env = evalTricu library (parseTricu input)
+      result env @?= Leaf
+  , testCase "K combinator 2" $ do
+      let input = "k (t t) (t)"
+          env = evalTricu library (parseTricu input)
+      result env @?= Stem Leaf
+  , testCase "K combinator 3" $ do
+      let input = "k (t t t) (t)"
+          env = evalTricu library (parseTricu input)
+      result env @?= Fork Leaf Leaf
+  , testCase "S combinator" $ do
+      let input = "s (t) (t) (t)"
+          env = evalTricu library (parseTricu input)
+      result env @?= Fork Leaf (Stem Leaf)
+  , testCase "SKK == I" $ do -- Tests for fully expanded I form
+      let input = "s k k"
+          env = evalTricu library (parseTricu input)
+      result env @?= Fork (Stem (Stem Leaf)) (Stem Leaf)
+  , testCase "I combinator" $ do
+      let input = "i not"
+          env = evalTricu library (parseTricu input)
+      result env @?= Fork (Fork (Stem Leaf) (Fork Leaf Leaf)) (Fork Leaf (Fork Leaf Leaf))
+  , testCase "Triage test Leaf" $ do
+      let input = "test t"
+          env = decodeResult $ result $ evalTricu library (parseTricu input)
+      env @?= "Leaf"
+  , testCase "Triage test (Stem Leaf)" $ do
+      let input = "test (t t)"
+          env = decodeResult $ result $ evalTricu library (parseTricu input)
+      env @?= "Stem"
+  , testCase "Triage test (Fork Leaf Leaf)" $ do
+      let input = "test (t t t)"
+          env = decodeResult $ result $ evalTricu library (parseTricu input)
+      env @?= "Fork"
+  , testCase "Boolean NOT: true" $ do
+      let input = "not true"
+          env = result $ evalTricu library (parseTricu input)
+      env @?= Leaf
+  , testCase "Boolean NOT: false" $ do
+      let input = "not false"
+          env = result $ evalTricu library (parseTricu input)
+      env @?= Stem Leaf
+  , testCase "Boolean AND TF" $ do
+      let input = "and (t t) (t)"
+          env = evalTricu library (parseTricu input)
+      result env @?= Leaf
+  , testCase "Boolean AND FT" $ do
+      let input = "and (t) (t t)"
+          env = evalTricu library (parseTricu input)
+      result env @?= Leaf
+  , testCase "Boolean AND FF" $ do
+      let input = "and (t) (t)"
+          env = evalTricu library (parseTricu input)
+      result env @?= Leaf
+  , testCase "Boolean AND TT" $ do
+      let input = "and (t t) (t t)"
+          env = evalTricu library (parseTricu input)
+      result env @?= Stem Leaf
+  , testCase "List head" $ do
+      let input = "head [(t) (t t) (t t t)]"
+          env = evalTricu library (parseTricu input)
+      result env @?= Leaf
+  , testCase "List tail" $ do
+      let input = "head (tail (tail [(t) (t t) (t t t)]))"
+          env = evalTricu library (parseTricu input)
+      result env @?= Fork Leaf Leaf
+  , testCase "List map" $ do
+      let input = "head (tail (map (\\a : (t t t)) [(t) (t) (t)]))"
+          env = evalTricu library (parseTricu input)
+      result env @?= Fork Leaf Leaf
+  , testCase "Empty list check" $ do
+      let input = "emptyList []"
+          env = evalTricu library (parseTricu input)
+      result env @?= Stem Leaf
+  , testCase "Non-empty list check" $ do
+      let input = "not (emptyList [(1) (2) (3)])"
+          env = evalTricu library (parseTricu input)
+      result env @?= Stem Leaf
+  , testCase "Concatenate strings" $ do
+      let input = "listConcat \"Hello, \" \"world!\""
+          env = decodeResult $ result $ evalTricu library (parseTricu input)
+      env @?= "Hello, world!"
+  , testCase "Verifying Equality" $ do
+      let input = "equal (t t t) (t t t)"
+          env = evalTricu library (parseTricu input)
+      result env @?= Stem Leaf
+  ]
+
 propertyTests :: TestTree
 propertyTests = testGroup "Property Tests"
   [ testProperty "Lexing and parsing round-trip" $ \input ->