diff --git a/demos/equality.tri b/demos/equality.tri
index d0008bf..86ace3b 100644
--- a/demos/equality.tri
+++ b/demos/equality.tri
@@ -1,4 +1,5 @@
-!import "lib/base.tri" !Local
+!import "../lib/base.tri" !Local
+!import "../lib/list.tri" !Local
 
 main = lambdaEqualsTC
 
diff --git a/demos/levelOrderTraversal.tri b/demos/levelOrderTraversal.tri
index 2a5d4ac..803a1dd 100644
--- a/demos/levelOrderTraversal.tri
+++ b/demos/levelOrderTraversal.tri
@@ -1,4 +1,5 @@
-!import "lib/base.tri" !Local
+!import "../lib/base.tri" Lib
+!import "../lib/list.tri" !Local
 
 main = exampleTwo
 -- Level Order Traversal of a labelled binary tree
diff --git a/demos/size.tri b/demos/size.tri
index 83c8937..cbfd6c9 100644
--- a/demos/size.tri
+++ b/demos/size.tri
@@ -1,4 +1,5 @@
-!import "lib/base.tri" !Local
+!import "../lib/base.tri" !Local
+!import "../lib/list.tri" !Local
 
 main = size size
 
diff --git a/demos/toSource.tri b/demos/toSource.tri
index f8a65f8..354943e 100644
--- a/demos/toSource.tri
+++ b/demos/toSource.tri
@@ -1,4 +1,5 @@
-!import "lib/base.tri" !Local
+!import "../lib/base.tri" !Local
+!import "../lib/list.tri" !Local
 
 main = toSource not?
 -- Thanks to intensionality, we can inspect the structure of a given value
diff --git a/lib/base.tri b/lib/base.tri
index 6a132b9..914bfe7 100644
--- a/lib/base.tri
+++ b/lib/base.tri
@@ -1,13 +1,8 @@
 false = t
 _     = t
 true  = t t
-k     = t t
-i     = t (t k) t
-s     = t (t (k t)) t
-m     = s i i
-b     = s (k s) k
-c     = s (s (k s) (s (k k) s)) (k k)
 id    = \a : a
+const = \a b : a
 pair  = t
 if    = \cond then else : t (t else (t t then)) t cond
 
@@ -26,33 +21,6 @@ matchBool = (\ot of : triage
   (\_ _ : ot)
 )
 
-matchList = \a b : triage a _ b
-
-matchPair = \a   : triage _ _ a
-
-not? = matchBool false true
-and? = matchBool id (\_ : false)
-emptyList? = matchList true (\_ _ : false)
-
-head = matchList t (\head _ : head)
-tail = matchList t (\_ tail : tail)
-
-or? = (\x y : 
-  matchBool 
-    (matchBool (t t) (t t) y)
-    (matchBool (t t) t y)
-    x)
-
-xor? = (\x y : 
-  matchBool 
-    (matchBool t (t t) y)
-    (matchBool (t t) t y)
-    x)
-
-append = y (\self : matchList
-  (\k : k)
-  (\h r k : pair h (self r k)))
-
 lAnd = (triage
   (\_     : false)
   (\_ x   : x)
@@ -63,11 +31,22 @@ lOr = (triage
   (\_ _   : true)
   (\_ _ _ : true))
 
-map_ = y (\self :
-  matchList
-    (\_ : t)
-    (\head tail f : pair (f head) (self tail f)))
-map = \f l : map_ l f
+matchPair = \a   : triage _ _ a
+
+not? = matchBool false true
+and? = matchBool id (\_ : false)
+
+or? = (\x z : 
+  matchBool 
+    (matchBool true true z)
+    (matchBool true false z)
+    x)
+
+xor? = (\x z : 
+  matchBool 
+    (matchBool false true z)
+    (matchBool true false z)
+    x)
 
 equal? = y (\self : triage
   (triage
@@ -85,21 +64,6 @@ equal? = y (\self : triage
       (\_ : false)
       (\bx by : lAnd (self ax bx) (self ay by))))
 
-lExist? = y (\self x : matchList
-  false
-  (\h z : or? (equal? x h) (self x z)))
-
-filter_ = y (\self : matchList
-  (\_ : t)
-  (\head tail f : matchBool (t head) i (f head) (self tail f)))
-filter  = \f l : filter_ l f
-
-foldl_ = y (\self f l x : matchList (\acc : acc) (\head tail acc : self f tail (f acc head)) l x)
-foldl  = \f x l : foldl_ f l x
-
-foldr_ = y (\self x f l : matchList x (\head tail : f (self x f tail) head) l)
-foldr  = \f x l : foldr_ x f l
-
 succ = y (\self :
   triage
     1
@@ -108,48 +72,3 @@ succ = y (\self :
       (t (t t))
       (\_ tail : t t (self tail))
       t))
-
-length = y (\self : matchList
-  0
-  (\_ tail : succ (self tail)))
-
-reverse = y (\self : matchList
-  t
-  (\head tail : append (self tail) (pair head t)))
-
-snoc = y (\self x : matchList
-  (pair x t)
-  (\h z : pair h (self x z)))
-
-count = y (\self x : matchList
-  0
-  (\h z : matchBool 
-    (succ (self x z))
-    (self x z)
-    (equal? x h)))
-
-last = y (\self : matchList
-  t
-  (\hd tl : matchBool
-    hd
-    (self tl)
-    (emptyList? tl)))
-
-all? = y (\self pred : matchList
-  true
-  (\h z : and? (pred h) (self pred z)))
-
-any? = y (\self pred : matchList
-  false
-  (\h z : or? (pred h) (self pred z)))
-
-unique_ = y (\self seen : matchList
-  t
-  (\head rest : matchBool
-    (self seen rest)
-    (pair head (self (pair head seen) rest))
-    (lExist? head seen)))
-unique = \xs : unique_ t xs
-
-intersect = \xs ys : filter (\x : lExist? x ys) xs
-union     = \xs ys : unique (append xs ys)
diff --git a/lib/list.tri b/lib/list.tri
new file mode 100644
index 0000000..d784a6b
--- /dev/null
+++ b/lib/list.tri
@@ -0,0 +1,77 @@
+!import "base.tri" !Local
+
+matchList = \a b : triage a _ b
+
+emptyList? = matchList true (\_ _ : false)
+head = matchList t (\head _ : head)
+tail = matchList t (\_ tail : tail)
+
+append = y (\self : matchList
+  (\k : k)
+  (\h r k : pair h (self r k)))
+
+lExist? = y (\self x : matchList
+  false
+  (\h z : or? (equal? x h) (self x z)))
+
+map_ = y (\self :
+  matchList
+    (\_ : t)
+    (\head tail f : pair (f head) (self tail f)))
+map = \f l : map_ l f
+
+filter_ = y (\self : matchList
+  (\_ : t)
+  (\head tail f : matchBool (t head) id (f head) (self tail f)))
+filter  = \f l : filter_ l f
+
+foldl_ = y (\self f l x : matchList (\acc : acc) (\head tail acc : self f tail (f acc head)) l x)
+foldl  = \f x l : foldl_ f l x
+
+foldr_ = y (\self x f l : matchList x (\head tail : f (self x f tail) head) l)
+foldr  = \f x l : foldr_ x f l
+
+length = y (\self : matchList
+  0
+  (\_ tail : succ (self tail)))
+
+reverse = y (\self : matchList
+  t
+  (\head tail : append (self tail) (pair head t)))
+
+snoc = y (\self x : matchList
+  (pair x t)
+  (\h z : pair h (self x z)))
+
+count = y (\self x : matchList
+  0
+  (\h z : matchBool
+    (succ (self x z))
+    (self x z)
+    (equal? x h)))
+
+last = y (\self : matchList
+  t
+  (\hd tl : matchBool
+    hd
+    (self tl)
+    (emptyList? tl)))
+
+all? = y (\self pred : matchList
+  true
+  (\h z : and? (pred h) (self pred z)))
+
+any? = y (\self pred : matchList
+  false
+  (\h z : or? (pred h) (self pred z)))
+
+unique_ = y (\self seen : matchList
+  t
+  (\head rest : matchBool
+    (self seen rest)
+    (pair head (self (pair head seen) rest))
+    (lExist? head seen)))
+unique = \xs : unique_ t xs
+
+intersect = \xs ys : filter (\x : lExist? x ys) xs
+union     = \xs ys : unique (append xs ys)
diff --git a/src/Eval.hs b/src/Eval.hs
index 202bcd7..832c351 100644
--- a/src/Eval.hs
+++ b/src/Eval.hs
@@ -141,18 +141,23 @@ reorderDefs env defs
 
 buildDepGraph :: [TricuAST] -> Map.Map String (Set.Set String)
 buildDepGraph topDefs
-  | not (null duplicateNames) =
+  | not (null conflictingDefs) =
       errorWithoutStackTrace $
-        "Duplicate definitions detected: " ++ show duplicateNames
+        "Conflicting definitions detected: " ++ show conflictingDefs
   | otherwise =
       Map.fromList
         [ (name, depends topDefs (SDef name [] body))
         | SDef name _ body <- topDefs]
   where
-    names = [name | SDef name _ _ <- topDefs]
-    duplicateNames =
-      [ name | (name, count) <- Map.toList (countOccurrences names) , count > 1]
-    countOccurrences = foldr (\x -> Map.insertWith (+) x 1) Map.empty
+    defsMap = Map.fromListWith (++)
+      [(name, [(name, body)]) | SDef name _ body <- topDefs]
+
+    conflictingDefs =
+      [ name
+      | (name, defs) <- Map.toList defsMap
+      , let bodies = map snd defs
+      , not $ all (== head bodies) (tail bodies)
+      ]
 
 sortDeps :: Map.Map String (Set.Set String) -> [String]
 sortDeps graph = go [] Set.empty (Map.keys graph)
diff --git a/src/FileEval.hs b/src/FileEval.hs
index af8ddc0..5b9845f 100644
--- a/src/FileEval.hs
+++ b/src/FileEval.hs
@@ -8,6 +8,7 @@ import Research
 import Data.List       (partition)
 import Control.Monad   (foldM)
 import System.IO
+import System.FilePath (takeDirectory, normalise, (</>))
 
 import qualified Data.Map as Map
 import qualified Data.Set as Set
@@ -46,38 +47,45 @@ evaluateFileWithContext env filePath = do
       pure $ evalTricu env ast
 
 preprocessFile :: FilePath -> IO [TricuAST]
-preprocessFile = preprocessFile' Set.empty
+preprocessFile p = preprocessFile' Set.empty p p
 
-preprocessFile' :: Set.Set FilePath -> FilePath -> IO [TricuAST]
-preprocessFile' inProgress filePath
-  | filePath `Set.member` inProgress = 
-      errorWithoutStackTrace $ "Encountered cyclic import: " ++ filePath
+preprocessFile' :: Set.Set FilePath -> FilePath -> FilePath -> IO [TricuAST]
+preprocessFile' s b p
+  | p `Set.member` s =
+      errorWithoutStackTrace $ "Encountered cyclic import: " ++ p
   | otherwise = do
-      contents <- readFile filePath
-      let tokens = lexTricu contents
-      case parseProgram tokens of
-        Left err -> errorWithoutStackTrace (handleParseError err)
-        Right asts -> do
-          let (imports, nonImports) = partition isImport asts
-          let newInProgress = Set.insert filePath inProgress
-          importedASTs <- concat <$> 
-            mapM (processImport newInProgress "") imports
-          pure $ importedASTs ++ nonImports
+      c <- readFile p
+      let t = lexTricu c
+      case parseProgram t of
+        Left e -> errorWithoutStackTrace (handleParseError e)
+        Right a -> do
+          let (i, n) = partition isImp a
+          let s' = Set.insert p s
+          r <- concat <$>
+            mapM (procImp s' "" p) i
+          pure $ r ++ n
   where
-    isImport :: TricuAST -> Bool
-    isImport (SImport _ _) = True
-    isImport _             = False
+    isImp :: TricuAST -> Bool
+    isImp (SImport _ _) = True
+    isImp _             = False
 
-    processImport :: Set.Set FilePath -> String -> TricuAST -> IO [TricuAST]
-    processImport prog currentModule (SImport path "!Local") = do
-      ast <- preprocessFile' prog path
-      let defs = filter (not . isImport) ast
-      pure $ map (nsDefinition currentModule) defs
-    processImport prog _ (SImport path name) = do
-      ast <- preprocessFile' prog path
-      let defs = filter (not . isImport) ast
-      pure $ map (nsDefinition name) defs
-    processImport _ _ _ = error "Unexpected non-import in processImport"
+    procImp :: Set.Set FilePath -> String -> FilePath -> TricuAST -> IO [TricuAST]
+    procImp s m f (SImport p "!Local") = do
+      let ip = makeRelativeTo f p
+      a <- preprocessFile' s b ip
+      let d = filter (not . isImp) a
+      pure $ map (nsDefinition m) d
+    procImp s _ f (SImport p n) = do
+      let ip = makeRelativeTo f p
+      a <- preprocessFile' s b ip
+      let d = filter (not . isImp) a
+      pure $ map (nsDefinition n) d
+    procImp _ _ _ _ = error "Unexpected non-import in processImport"
+
+makeRelativeTo :: FilePath -> FilePath -> FilePath
+makeRelativeTo f i =
+    let d = takeDirectory f
+    in normalise $ d </> i
 
 nsDefinitions :: String -> [TricuAST] -> [TricuAST]
 nsDefinitions moduleName = map (nsDefinition moduleName)
diff --git a/test/Spec.hs b/test/Spec.hs
index d657a60..a1912de 100644
--- a/test/Spec.hs
+++ b/test/Spec.hs
@@ -30,7 +30,7 @@ tests = testGroup "Tricu Tests"
   , parser
   , simpleEvaluation
   , lambdas
-  , baseLibrary
+  , providedLibraries
   , fileEval
   , modules
   , demos
@@ -343,137 +343,101 @@ lambdas = testGroup "Lambda Evaluation Tests"
         runTricu input @?= "Fork Leaf (Fork (Stem Leaf) Leaf)"
   ]
 
-baseLibrary :: TestTree
-baseLibrary = testGroup "Library Tests"
-  [ testCase "K combinator 1" $ do
-      library <- evaluateFile "./lib/base.tri"
-      let input = "k (t) (t t)"
-          env = evalTricu library (parseTricu input)
-      result env @?= Leaf
-
-  , testCase "K combinator 2" $ do
-      library <- evaluateFile "./lib/base.tri"
-      let input = "k (t t) (t)"
-          env = evalTricu library (parseTricu input)
-      result env @?= Stem Leaf
-
-  , testCase "K combinator 3" $ do
-      library <- evaluateFile "./lib/base.tri"
-      let input = "k (t t t) (t)"
-          env = evalTricu library (parseTricu input)
-      result env @?= Fork Leaf Leaf
-
-  , testCase "S combinator" $ do
-      library <- evaluateFile "./lib/base.tri"
-      let input = "s (t) (t) (t)"
-          env = evalTricu library (parseTricu input)
-      result env @?= Fork Leaf (Stem Leaf)
-
-  , testCase "SKK == I (fully expanded)" $ do
-      library <- evaluateFile "./lib/base.tri"
-      let input = "s k k"
-          env = evalTricu library (parseTricu input)
-      result env @?= Fork (Stem (Stem Leaf)) (Stem Leaf)
-
-  , testCase "I combinator" $ do
-      library <- evaluateFile "./lib/base.tri"
-      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
-      library <- evaluateFile "./lib/base.tri"
+providedLibraries :: TestTree
+providedLibraries = testGroup "Library Tests"
+  [ testCase "Triage test Leaf" $ do
+      library <- evaluateFile "./lib/list.tri"
       let input = "test t"
           env = decodeResult $ result $ evalTricu library (parseTricu input)
       env @?= "\"Leaf\""
 
   , testCase "Triage test (Stem Leaf)" $ do
-      library <- evaluateFile "./lib/base.tri"
+      library <- evaluateFile "./lib/list.tri"
       let input = "test (t t)"
           env = decodeResult $ result $ evalTricu library (parseTricu input)
       env @?= "\"Stem\""
 
   , testCase "Triage test (Fork Leaf Leaf)" $ do
-      library <- evaluateFile "./lib/base.tri"
+      library <- evaluateFile "./lib/list.tri"
       let input = "test (t t t)"
           env = decodeResult $ result $ evalTricu library (parseTricu input)
       env @?= "\"Fork\""
 
   , testCase "Boolean NOT: true" $ do
-      library <- evaluateFile "./lib/base.tri"
+      library <- evaluateFile "./lib/list.tri"
       let input = "not? true"
           env = result $ evalTricu library (parseTricu input)
       env @?= Leaf
 
   , testCase "Boolean NOT: false" $ do
-      library <- evaluateFile "./lib/base.tri"
+      library <- evaluateFile "./lib/list.tri"
       let input = "not? false"
           env = result $ evalTricu library (parseTricu input)
       env @?= Stem Leaf
 
 
   , testCase "Boolean AND TF" $ do
-      library <- evaluateFile "./lib/base.tri"
+      library <- evaluateFile "./lib/list.tri"
       let input = "and? (t t) (t)"
           env = evalTricu library (parseTricu input)
       result env @?= Leaf
 
   , testCase "Boolean AND FT" $ do
-      library <- evaluateFile "./lib/base.tri"
+      library <- evaluateFile "./lib/list.tri"
       let input = "and? (t) (t t)"
           env = evalTricu library (parseTricu input)
       result env @?= Leaf
 
   , testCase "Boolean AND FF" $ do
-      library <- evaluateFile "./lib/base.tri"
+      library <- evaluateFile "./lib/list.tri"
       let input = "and? (t) (t)"
           env = evalTricu library (parseTricu input)
       result env @?= Leaf
 
   , testCase "Boolean AND TT" $ do
-      library <- evaluateFile "./lib/base.tri"
+      library <- evaluateFile "./lib/list.tri"
       let input = "and? (t t) (t t)"
           env = evalTricu library (parseTricu input)
       result env @?= Stem Leaf
 
   , testCase "List head" $ do
-      library <- evaluateFile "./lib/base.tri"
+      library <- evaluateFile "./lib/list.tri"
       let input = "head [(t) (t t) (t t t)]"
           env = evalTricu library (parseTricu input)
       result env @?= Leaf
 
   , testCase "List tail" $ do
-      library <- evaluateFile "./lib/base.tri"
+      library <- evaluateFile "./lib/list.tri"
       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
-      library <- evaluateFile "./lib/base.tri"
+      library <- evaluateFile "./lib/list.tri"
       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
-      library <- evaluateFile "./lib/base.tri"
+      library <- evaluateFile "./lib/list.tri"
       let input = "emptyList? []"
           env = evalTricu library (parseTricu input)
       result env @?= Stem Leaf
 
   , testCase "Non-empty list check" $ do
-      library <- evaluateFile "./lib/base.tri"
+      library <- evaluateFile "./lib/list.tri"
       let input = "not? (emptyList? [(1) (2) (3)])"
           env = evalTricu library (parseTricu input)
       result env @?= Stem Leaf
 
   , testCase "Concatenate strings" $ do
-      library <- evaluateFile "./lib/base.tri"
+      library <- evaluateFile "./lib/list.tri"
       let input = "append \"Hello, \" \"world!\""
           env = decodeResult $ result $ evalTricu library (parseTricu input)
       env @?= "\"Hello, world!\""
 
   , testCase "Verifying Equality" $ do
-      library <- evaluateFile "./lib/base.tri"
+      library <- evaluateFile "./lib/list.tri"
       let input = "equal? (t t t) (t t t)"
           env = evalTricu library (parseTricu input)
       result env @?= Stem Leaf
@@ -490,12 +454,12 @@ fileEval = testGroup "File evaluation tests"
       res @?= Fork (Stem Leaf) Leaf
 
   , testCase "Mapping and Equality" $ do
-      library <- liftIO $ evaluateFile "./lib/base.tri"
+      library <- liftIO $ evaluateFile "./lib/list.tri"
       fEnv    <- liftIO $ evaluateFileWithContext library "./test/map.tri"
       (mainResult fEnv) @?= Stem Leaf
 
   , testCase "Eval and decoding string" $ do
-      library <- liftIO $ evaluateFile "./lib/base.tri"
+      library <- liftIO $ evaluateFile "./lib/list.tri"
       res <- liftIO $ evaluateFileWithContext library "./test/string.tri"
       decodeResult (result res) @?= "\"String test!\""
   ]
diff --git a/test/cycle-1.tri b/test/cycle-1.tri
index f77d6c1..40d9fa2 100644
--- a/test/cycle-1.tri
+++ b/test/cycle-1.tri
@@ -1,4 +1,4 @@
 
-!import "test/cycle-2.tri" Cycle2
+!import "cycle-2.tri" Cycle2
 
 cycle1 = t Cycle2.cycle2
diff --git a/test/cycle-2.tri b/test/cycle-2.tri
index 61e911a..5336f1e 100644
--- a/test/cycle-2.tri
+++ b/test/cycle-2.tri
@@ -1,4 +1,4 @@
 
-!import "test/cycle-1.tri" Cycle1
+!import "cycle-1.tri" Cycle1
 
 cycle2 = t Cycle1.cycle1
diff --git a/test/local-ns/1.tri b/test/local-ns/1.tri
index fd10a99..e461a5e 100644
--- a/test/local-ns/1.tri
+++ b/test/local-ns/1.tri
@@ -1,4 +1,4 @@
 
-!import "test/local-ns/2.tri" Two
+!import "2.tri" Two
 
 main = Two.x
diff --git a/test/local-ns/2.tri b/test/local-ns/2.tri
index 6296138..729429b 100644
--- a/test/local-ns/2.tri
+++ b/test/local-ns/2.tri
@@ -1,2 +1,2 @@
 
-!import "test/local-ns/3.tri" !Local
+!import "3.tri" !Local
diff --git a/test/local-ns/3.tri b/test/local-ns/3.tri
index 6d16539..b95c23a 100644
--- a/test/local-ns/3.tri
+++ b/test/local-ns/3.tri
@@ -1,2 +1 @@
-
 x = 3
diff --git a/test/multi-level-A.tri b/test/multi-level-A.tri
index 53a23b2..3553c2c 100644
--- a/test/multi-level-A.tri
+++ b/test/multi-level-A.tri
@@ -1,2 +1,2 @@
-!import "./test/multi-level-B.tri" B
+!import "multi-level-B.tri" B
 main = B.main
diff --git a/test/multi-level-B.tri b/test/multi-level-B.tri
index 63164d0..115d591 100644
--- a/test/multi-level-B.tri
+++ b/test/multi-level-B.tri
@@ -1,2 +1,2 @@
-!import "./test/multi-level-C.tri" C
+!import "multi-level-C.tri" C
 main = C.val
diff --git a/test/namespace-A.tri b/test/namespace-A.tri
index 06813f9..5d24219 100644
--- a/test/namespace-A.tri
+++ b/test/namespace-A.tri
@@ -1,2 +1,2 @@
-!import "./test/namespace-B.tri" B
+!import "namespace-B.tri" B
 main = B.x
diff --git a/test/vars-A.tri b/test/vars-A.tri
index 3336f41..1f38f8d 100644
--- a/test/vars-A.tri
+++ b/test/vars-A.tri
@@ -1,6 +1,6 @@
 
-!import "./test/vars-B.tri" B
+!import "vars-B.tri" B
 
-!import "./test/vars-C.tri" C
+!import "vars-C.tri" C
 
 main = B.y (C.z)
diff --git a/tricu.cabal b/tricu.cabal
index ed98ad0..e0a4b21 100644
--- a/tricu.cabal
+++ b/tricu.cabal
@@ -1,7 +1,7 @@
 cabal-version: 1.12
 
 name:           tricu
-version:        0.13.2
+version:        0.14.0
 description:    A micro-language for exploring Tree Calculus
 author:         James Eversole
 maintainer:     james@eversole.co
@@ -27,6 +27,7 @@ executable tricu
     , cmdargs
     , containers
     , exceptions
+    , filepath
     , haskeline
     , megaparsec
     , mtl
@@ -54,6 +55,7 @@ test-suite tricu-tests
     , cmdargs
     , containers
     , exceptions
+    , filepath
     , haskeline
     , megaparsec
     , mtl