diff --git a/README.md b/README.md
index e543e10..0aa47d0 100644
--- a/README.md
+++ b/README.md
@@ -58,7 +58,7 @@ You can easily build and/or run this project using [Nix](https://nixos.org/downl
 `./result/bin/tricu --help`
 
 ```
-tricu - compiler and repl
+tricu Evaluator and REPL
 
 tricu [COMMAND] ... [OPTIONS]
   tricu: Exploring Tree Calculus
@@ -70,17 +70,20 @@ Common flags:
 tricu [repl] [OPTIONS]
   Start interactive REPL
 
-tricu compile [OPTIONS]
-  Compile a file and return the result of the expression in the final line
+tricu eval [OPTIONS]
+  Evaluate a file and return the result of the expression in the final line
 
-  -f --file=FILE      Relative or absolute path to file input for compilation
-  -o --output=OUTPUT  Optional output file path for resulting output
-  -t --form=FORM      Output form: (fsl|tree|ast|ternary|ascii)
+  -f --file=FILE      Optional input file path for evaluation.
+                      Defaults to stdin.
+  -o --output=OUTPUT  Optional output file path for resulting output.
+                      Defaults to stdout.
+  -t --form=FORM      Optional output form: (fsl|tree|ast|ternary|ascii).
+                      Defaults to fsl.
 
 tricu decode [OPTIONS]
   Decode a Tree Calculus value into a string representation
 
-  -f --input=FILE     Optional file path containing a Tree Calculus value.
+  -f --input=ITEM     Optional file path to attempt decoding.
                       Defaults to stdin.
 ```
 
diff --git a/src/Eval.hs b/src/Eval.hs
index 3d31b36..5ebb9f1 100644
--- a/src/Eval.hs
+++ b/src/Eval.hs
@@ -13,7 +13,7 @@ evalSingle env term = case term of
   SFunc name [] body ->
     let lineNoLambda = eliminateLambda body
         result = evalAST env lineNoLambda
-    in Map.insert name result env
+    in Map.insert "__result" result (Map.insert name result env)
   SLambda _ body ->
     let result = evalAST env body
     in Map.insert "__result" result env
diff --git a/src/Compiler.hs b/src/FileEval.hs
similarity index 95%
rename from src/Compiler.hs
rename to src/FileEval.hs
index 8906306..5b2a727 100644
--- a/src/Compiler.hs
+++ b/src/FileEval.hs
@@ -1,4 +1,4 @@
-module Compiler where
+module FileEval where
 
 import Eval
 import Library
diff --git a/src/Main.hs b/src/Main.hs
index a8e82ff..91c7bd9 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -1,7 +1,7 @@
 module Main where
 
-import Compiler
 import Eval                   (evalTricu, result)
+import FileEval
 import Library                (library)
 import Parser                 (parseTricu)
 import REPL
@@ -14,7 +14,7 @@ import qualified Data.Map as Map
 
 data TricuArgs
   = Repl
-  | Compile { file :: FilePath, output :: Maybe FilePath, form :: CompiledForm }
+  | Evaluate { file :: Maybe FilePath, output :: Maybe FilePath, form :: EvaluatedForm }
   | Decode { input :: Maybe FilePath }
   deriving (Show, Data, Typeable)
 
@@ -24,24 +24,24 @@ replMode = Repl
   &= auto
   &= name "repl"
 
-compileMode :: TricuArgs
-compileMode = Compile 
+evaluateMode :: TricuArgs
+evaluateMode = Evaluate 
   { file = def &= typ "FILE" 
-      &= help "Relative or absolute path to file input for compilation" &= name "f"
+      &= help "Optional input file path for evaluation.\nDefaults to stdin." &= name "f"
   , output = def &= typ "OUTPUT" 
-      &= help "Optional output file path for resulting output" &= name "o"
+      &= help "Optional output file path for resulting output.\nDefaults to stdout." &= name "o"
   , form = FSL &= typ "FORM" 
-      &= help "Output form: (fsl|tree|ast|ternary|ascii)" 
+      &= help "Optional output form: (fsl|tree|ast|ternary|ascii).\nDefaults to fsl." 
       &= name "t"
   }
-  &= help "Compile a file and return the result of the expression in the final line"
+  &= help "Evaluate a file and return the result of the expression in the final line"
   &= explicit
-  &= name "compile"
+  &= name "eval"
 
 decodeMode :: TricuArgs
 decodeMode = Decode
   { input = def &= typ "FILE"
-            &= help "Optional file path containing a Tree Calculus value. Defaults to stdin." &= name "f"
+            &= help "Optional file path to attempt decoding.\nDefaults to stdin." &= name "f"
   }
   &= help "Decode a Tree Calculus value into a string representation"
   &= explicit
@@ -49,18 +49,22 @@ decodeMode = Decode
 
 main :: IO ()
 main = do
-  args <- cmdArgs $ modes [replMode, compileMode, decodeMode]
+  args <- cmdArgs $ modes [replMode, evaluateMode, decodeMode]
     &= help "tricu: Exploring Tree Calculus"
     &= program "tricu"
-    &= summary "tricu - compiler and repl"
+    &= summary "tricu Evaluator and REPL"
 
   case args of
     Repl -> do
       putStrLn "Welcome to the tricu REPL"
       putStrLn "You can exit with `CTRL+D` or the `:_exit` command.`"
       repl library
-    Compile { file = filePath, output = maybeOutputPath, form = form } -> do
-      result <- evaluateFile filePath
+    Evaluate { file = maybeFilePath, output = maybeOutputPath, form = form } -> do
+      result <- case maybeFilePath of
+        Just filePath -> evaluateFile filePath
+        Nothing -> do 
+          t <- getContents
+          pure $ runTricu t
       let fRes = formatResult form result
       case maybeOutputPath of
         Just outputPath -> do
@@ -72,3 +76,6 @@ main = do
         Just inputPath -> readFile inputPath
         Nothing -> getContents
       putStrLn $ decodeResult $ result $ evalTricu library $ parseTricu value
+
+runTricu :: String -> T
+runTricu = result . evalTricu Map.empty . parseTricu
diff --git a/src/Research.hs b/src/Research.hs
index 6665fb9..e22071a 100644
--- a/src/Research.hs
+++ b/src/Research.hs
@@ -45,7 +45,7 @@ data LToken
   deriving (Show, Eq, Ord)
 
 -- Output formats
-data CompiledForm = TreeCalculus | FSL | AST | Ternary | Ascii
+data EvaluatedForm = TreeCalculus | FSL | AST | Ternary | Ascii
   deriving (Show, Data, Typeable)
 
 -- Environment containing previously evaluated TC terms
@@ -122,7 +122,7 @@ toList (Fork x rest) = case toList rest of
 toList _ = Left "Invalid Tree Calculus list"
 
 -- Outputs
-formatResult :: CompiledForm -> T -> String
+formatResult :: EvaluatedForm -> T -> String
 formatResult TreeCalculus = toSimpleT . show
 formatResult FSL          = show
 formatResult AST          = show . toAST
diff --git a/test/Spec.hs b/test/Spec.hs
index cfc4142..cdcdff3 100644
--- a/test/Spec.hs
+++ b/test/Spec.hs
@@ -1,7 +1,7 @@
 module Main where
 
-import Compiler
 import Eval
+import FileEval
 import Lexer
 import Library
 import Parser
@@ -31,7 +31,7 @@ tests = testGroup "Tricu Tests"
   , evaluationTests
   , lambdaEvalTests
   , libraryTests
-  , compilerTests
+  , fileEvaluationTests
   , propertyTests
   ]
 
@@ -377,8 +377,8 @@ libraryTests = testGroup "Library Tests"
       result env @?= Stem Leaf
   ]
 
-compilerTests :: TestTree
-compilerTests = testGroup "Compiler tests"
+fileEvaluationTests :: TestTree
+fileEvaluationTests = testGroup "Evaluation tests"
   [ testCase "Forks" $ do
       res <- liftIO $ evaluateFile "./test/fork.tri"
       res @?= Fork Leaf Leaf
@@ -388,7 +388,7 @@ compilerTests = testGroup "Compiler tests"
   , testCase "Mapping and Equality" $ do
       res <- liftIO $ evaluateFile "./test/map.tri"
       res @?= Stem Leaf
-  , testCase "Map evaluation to String -> compilation -> string decoding" $ do
+  , testCase "Eval and decoding string" $ do
       res <- liftIO $ evaluateFile "./test/string.tri"
       decodeResult res @?= "String test!"
   ]
diff --git a/test/assignment.tri b/test/assignment.tri
new file mode 100644
index 0000000..9749e3b
--- /dev/null
+++ b/test/assignment.tri
@@ -0,0 +1 @@
+x = t (t t) t
diff --git a/tricu.cabal b/tricu.cabal
index 012500e..8c1e7c9 100644
--- a/tricu.cabal
+++ b/tricu.cabal
@@ -29,8 +29,8 @@ executable tricu
     , mtl
     , text
   other-modules:
-    Compiler
     Eval
+    FileEval
     Lexer
     Library
     Parser
@@ -58,8 +58,8 @@ test-suite tricu-tests
     , text
   default-language:    Haskell2010
   other-modules:
-    Compiler
     Eval
+    FileEval
     Lexer
     Library
     Parser