Statically link binaries

Also removes some broken list library functions

.gitignore

@@ -9,3 +9,4 @@
 WD
 bin/
 dist*
+.tricu_history

README.md

@@ -41,6 +41,16 @@ tricu > "(t (t (t t) (t t t)) (t t (t t t)))"
 tricu < -- or calculate its size (/demos/size.tri)
 tricu < size not?
 tricu > 12
+
+tricu < -- REPL Commands:
+tricu < !definitions  -- Lists all available definitions
+tricu < !output       -- Change output format (Tree, FSL, AST, etc.)
+tricu < !import       -- Import definitions from a file
+tricu < !exit         -- Exit the REPL
+tricu < !clear        -- ANSI screen clear
+tricu < !save         -- Save all REPL definitions to a file that you can !import
+tricu < !reset        -- Clear all REPL definitions
+tricu < !version      -- Print tricu version
 ```
 
 ## Installation and Use
@@ -84,6 +94,12 @@ tricu decode [OPTIONS]
                     Defaults to stdin.
 ```
 
+## Collaborating
+
+I am happy to accept issue reports, pull requests, or questions about tricu [via email](mailto:james@eversole.co).
+
+If you want to collaborate but don't want to email back-and-forth, please reach out via email once to let me know and I will provision a git.eversole.co account for you.
+
 ## Acknowledgements 
 
 Tree Calculus was discovered by [Barry Jay](https://github.com/barry-jay-personal/blog). 

flake.nix

@@ -2,45 +2,57 @@
   description = "tricu";
 
   inputs = {
-    nixpkgs.url = "github:NixOS/nixpkgs";
+    nixpkgs = {
-    flake-utils.url = "github:numtide/flake-utils";
+      url = "https://github.com/nh2/nixpkgs/archive/ede5282c487a1fd2de64303ba59adad6726f1225.tar.gz";
+      type = "tarball";
+      flake = false;
+    };
+    static-haskell-nix = {
+      url = "github:nh2/static-haskell-nix";
+      flake = false;
+    };
   };
 
-  outputs = { self, nixpkgs, flake-utils }:
+  outputs = { self, nixpkgs, static-haskell-nix }:
-    flake-utils.lib.eachDefaultSystem (system:
+    let
-      let
+      system = "x86_64-linux";
-        pkgs              = nixpkgs.legacyPackages.${system};
+      compiler = "ghc948";
-        packageName       = "tricu";
+      packageName = "tricu";
-        containerPackageName = "${packageName}-container";
 
-        customGHC = pkgs.haskellPackages.ghcWithPackages (hpkgs: with hpkgs; [
+      overlay = self: super: {
-          megaparsec
+        haskell = super.haskell // {
-        ]);
+          packages = super.haskell.packages // {
-
+            ${compiler} = super.haskell.packages.${compiler}.override {
-        haskellPackages = pkgs.haskellPackages;
+              overrides = final: prev: {
-
+                ${packageName} = prev.callCabal2nix packageName ./. {};
-        enableSharedExecutables = false;
+              };
-        enableSharedLibraries = false;
+            };
-
+          };
-        tricu = pkgs.haskell.lib.justStaticExecutables self.packages.${system}.default;
-      in {
-
-        packages.${packageName} =
-          haskellPackages.callCabal2nix packageName self rec {};
-
-        packages.default = self.packages.${system}.${packageName};
-        defaultPackage = self.packages.${system}.default;
-
-        devShells.default = pkgs.mkShell {
-          buildInputs = with pkgs; [
-            haskellPackages.cabal-install
-            haskellPackages.ghcid
-            customGHC
-            upx
-          ];
-          inputsFrom = builtins.attrValues self.packages.${system};
         };
-        devShell = self.devShells.${system}.default;
+      };
 
-      });
+      overlays = [overlay];
+
+      normalPkgs = import nixpkgs { inherit overlays system; };
+
+      survey = import "${static-haskell-nix}/survey" { inherit compiler normalPkgs; };
+
+      tricuStatic = survey.haskellPackages.${packageName};
+
+    in {
+      packages.${system}.default = tricuStatic;
+
+      devShells.default = normalPkgs.mkShell {
+        buildInputs = with normalPkgs; [
+          normalPkgs.haskellPackages.cabal-install
+          normalPkgs.haskellPackages.ghc-events
+          normalPkgs.haskellPackages.ghcid
+          normalPkgs.upx
+        ];
+        inputsFrom = builtins.attrValues self.packages.${system};
+      };
+
+      devShell = self.devShells.${system}.default;
+    };
 }
+

lib/base.tri

@@ -31,7 +31,7 @@ lOr = (triage
   (\_ _   : true)
   (\_ _ _ : true))
 
-matchPair = \a   : triage _ _ a
+matchPair = \a : triage _ _ a
 
 not? = matchBool false true
 and? = matchBool id (\_ : false)

lib/list.tri

@@ -65,13 +65,4 @@ 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)

lib/patterns.tri

@@ -0,0 +1,36 @@
+!import "list.tri" !Local
+
+match_ = y (\self value patterns :
+  triage
+    t
+    (\_ : t)
+    (\pattern rest :
+      triage
+        t
+        (\_ : t)
+        (\test result :
+          if (test value)
+             (result value)
+             (self value rest))
+        pattern)
+    patterns)
+
+match = (\value patterns :
+  match_ value (map (\sublist :
+    pair (head sublist) (head (tail sublist)))
+    patterns))
+
+otherwise = const (t t)
+
+matchExample = (\x : match x
+  [[(equal? 1)  (\_ : "one")]
+  [(equal? 2)  (\_ : "two")]
+  [(equal? 3)  (\_ : "three")]
+  [(equal? 4)  (\_ : "four")]
+  [(equal? 5)  (\_ : "five")]
+  [(equal? 6)  (\_ : "six")]
+  [(equal? 7)  (\_ : "seven")]
+  [(equal? 8)  (\_ : "eight")]
+  [(equal? 9)  (\_ : "nine")]
+  [(equal? 10) (\_ : "ten")]
+  [ otherwise  (\_ : "I ran out of fingers!")]])

src/Eval.hs

@@ -75,6 +75,9 @@ elimLambda = go
     go (SLambda [f] (SLambda [g] (SLambda [x] body)))
       | body == SApp (SVar f) (SApp (SVar g) (SVar x)) = _B
     -- General elimination
+    go (SLambda [v] (SList xs))
+      = elimLambda (SLambda [v] (foldr wrapTLeaf TLeaf xs))
+        where wrapTLeaf m r = SApp (SApp TLeaf m) r
     go (SLambda (v:vs) body)
       | null vs                    = toSKI v (elimLambda body)
       | otherwise                  = elimLambda (SLambda [v] (SLambda vs body))

src/FileEval.hs

@@ -6,6 +6,7 @@ import Parser
 import Research
 
 import Data.List       (partition)
+import Data.Maybe      (mapMaybe)
 import Control.Monad   (foldM)
 import System.IO
 import System.FilePath (takeDirectory, normalise, (</>))
@@ -13,6 +14,26 @@ import System.FilePath (takeDirectory, normalise, (</>))
 import qualified Data.Map as Map
 import qualified Data.Set as Set
 
+extractMain :: Env -> Either String T
+extractMain env =
+  case Map.lookup "main" env of
+    Just result -> Right result
+    Nothing -> Left "No `main` function detected"
+
+processImports :: Set.Set FilePath -> FilePath -> FilePath -> [TricuAST]
+                 -> Either String ([TricuAST], [(FilePath, String, FilePath)])
+processImports seen base currentPath asts =
+  let (imports, nonImports) = partition isImp asts
+      importPaths = mapMaybe getImportInfo imports
+  in if currentPath `Set.member` seen
+     then Left $ "Encountered cyclic import: " ++ currentPath
+     else Right (nonImports, importPaths)
+  where
+    isImp (SImport _ _) = True
+    isImp _ = False
+    getImportInfo (SImport p n) = Just (p, n, makeRelativeTo currentPath p)
+    getImportInfo _ = Nothing
+
 evaluateFileResult :: FilePath -> IO T
 evaluateFileResult filePath = do
   contents <- readFile filePath
@@ -20,11 +41,11 @@ evaluateFileResult filePath = do
   case parseProgram tokens of
     Left err -> errorWithoutStackTrace (handleParseError err)
     Right ast -> do
-      ast <- preprocessFile filePath
+      processedAst <- preprocessFile filePath
-      let finalEnv = evalTricu Map.empty ast
+      let finalEnv = evalTricu Map.empty processedAst
-      case Map.lookup "main" finalEnv of
+      case extractMain finalEnv of
-        Just finalResult -> return finalResult
+        Right result -> return result
-        Nothing -> errorWithoutStackTrace "No `main` function detected"
+        Left err -> errorWithoutStackTrace err
 
 evaluateFile :: FilePath -> IO Env
 evaluateFile filePath = do
@@ -50,37 +71,25 @@ preprocessFile :: FilePath -> IO [TricuAST]
 preprocessFile p = preprocessFile' Set.empty p p
 
 preprocessFile' :: Set.Set FilePath -> FilePath -> FilePath -> IO [TricuAST]
-preprocessFile' s b p
+preprocessFile' seen base currentPath = do
-  | p `Set.member` s =
+  contents <- readFile currentPath
-      errorWithoutStackTrace $ "Encountered cyclic import: " ++ p
+  let tokens = lexTricu contents
-  | otherwise = do
+  case parseProgram tokens of
-      c <- readFile p
+    Left err -> errorWithoutStackTrace (handleParseError err)
-      let t = lexTricu c
+    Right ast ->
-      case parseProgram t of
+      case processImports seen base currentPath ast of
-        Left e -> errorWithoutStackTrace (handleParseError e)
+        Left err -> errorWithoutStackTrace err
-        Right a -> do
+        Right (nonImports, importPaths) -> do
-          let (i, n) = partition isImp a
+          let seen' = Set.insert currentPath seen
-          let s' = Set.insert p s
+          imported <- concat <$> mapM (processImportPath seen' base) importPaths
-          r <- concat <$>
+          pure $ imported ++ nonImports
-            mapM (procImp s' "" p) i
-          pure $ r ++ n
   where
-    isImp :: TricuAST -> Bool
+    processImportPath seen base (path, name, importPath) = do
+      ast <- preprocessFile' seen base importPath
+      pure $ map (nsDefinition (if name == "!Local" then "" else name))
+           $ filter (not . isImp) ast
     isImp (SImport _ _) = True
-    isImp _             = False
+    isImp _ = False
-
-    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 =

src/Lexer.hs

@@ -3,6 +3,7 @@ module Lexer where
 import Research
 
 import Control.Monad               (void)
+import Data.Functor                (($>))
 import Data.Void
 import Text.Megaparsec
 import Text.Megaparsec.Char hiding (space)
@@ -54,7 +55,7 @@ lexTricu input = case runParser tricuLexer "" input of
 
 
 keywordT :: Lexer LToken
-keywordT = string "t" *> notFollowedBy alphaNumChar *> pure LKeywordT
+keywordT = string "t" *> notFollowedBy alphaNumChar $> LKeywordT
 
 identifier :: Lexer LToken
 identifier = do
@@ -63,7 +64,7 @@ identifier = do
               <|> digitChar <|> char '_' <|> char '-' <|> char '?'
               <|> char '$'  <|> char '#' <|> char '@' <|> char '%'
   let name = first : rest
-  if (name == "t" || name == "!result")
+  if name == "t" || name == "!result"
     then fail "Keywords (`t`, `!result`) cannot be used as an identifier"
     else return (LIdentifier name)
 
@@ -76,7 +77,7 @@ namespace = do
   return (LNamespace name)
 
 dot :: Lexer LToken
-dot = char '.' *> pure LDot
+dot = char '.' $> LDot
 
 lImport :: Lexer LToken
 lImport = do
@@ -88,28 +89,28 @@ lImport = do
   return (LImport path name)
 
 assign :: Lexer LToken
-assign = char '=' *> pure LAssign
+assign = char '=' $> LAssign
 
 colon :: Lexer LToken
-colon = char ':' *> pure LColon
+colon = char ':' $> LColon
 
 backslash :: Lexer LToken
-backslash = char '\\' *> pure LBackslash
+backslash = char '\\' $> LBackslash
 
 openParen :: Lexer LToken
-openParen = char '(' *> pure LOpenParen
+openParen = char '(' $> LOpenParen
 
 closeParen :: Lexer LToken
-closeParen = char ')' *> pure LCloseParen
+closeParen = char ')' $> LCloseParen
 
 openBracket :: Lexer LToken
-openBracket = char '[' *> pure LOpenBracket
+openBracket = char '[' $> LOpenBracket
 
 closeBracket :: Lexer LToken
-closeBracket = char ']' *> pure LCloseBracket
+closeBracket = char ']' $> LCloseBracket
 
 lnewline :: Lexer LToken
-lnewline = char '\n' *> pure LNewline
+lnewline = char '\n' $> LNewline
 
 sc :: Lexer ()
 sc = space

src/Parser.hs

@@ -3,12 +3,12 @@ module Parser where
 import Lexer
 import Research
 
-import Control.Monad (void)
+import Control.Monad             (void)
 import Control.Monad.State
-import Data.List.NonEmpty (toList)
+import Data.List.NonEmpty        (toList)
-import Data.Void (Void)
+import Data.Void                 (Void)
 import Text.Megaparsec
-import Text.Megaparsec.Error (ParseErrorBundle, errorBundlePretty)
+import Text.Megaparsec.Error     (ParseErrorBundle, errorBundlePretty)
 import qualified Data.Set as Set
 
 data PState = PState

src/REPL.hs

@@ -6,68 +6,154 @@ import Lexer
 import Parser
 import Research
 
-import Control.Exception      (SomeException, catch)
+import Control.Exception         (IOException, SomeException, catch, displayException)
-import Control.Monad.IO.Class (liftIO)
+import Control.Monad             (forM_)
-import Control.Monad.Catch    (handle, MonadCatch)
+import Control.Monad.IO.Class    (liftIO)
-import Data.Char              (isSpace)
+import Control.Monad.Catch       (handle, MonadCatch)
-import Data.List              ( dropWhile
+import Control.Monad.Trans.Class (lift)
-                              , dropWhileEnd
+import Control.Monad.Trans.Maybe (MaybeT(..), runMaybeT)
-                              , intercalate
+import Data.Char                 (isSpace, isUpper)
-                              , isPrefixOf)
+import Data.List                 ( dropWhile
+                                 , dropWhileEnd
+                                 , isPrefixOf)
 import System.Console.Haskeline
+import Paths_tricu (version)
+import Data.Version (showVersion)
+import qualified Data.Text as T
+import qualified Data.Text.IO as T
 
 import qualified Data.Map as Map
 
 repl :: Env -> IO ()
-repl env = runInputT defaultSettings (withInterrupt (loop env True))
+repl env = runInputT settings (withInterrupt (loop env Decode))
   where
-    loop :: Env -> Bool -> InputT IO ()
+    settings :: Settings IO
-    loop env decode = handle (interruptHandler env decode) $ do
+    settings = Settings
+      { complete = completeWord Nothing " \t" completeCommands
+      , historyFile = Just "~/.local/state/tricu/history"
+      , autoAddHistory = True
+      }
+
+    completeCommands :: String -> IO [Completion]
+    completeCommands str = return $ map simpleCompletion $
+      filter (str `isPrefixOf`) commands
+      where
+        commands = [ "!exit"
+                   , "!output"
+                   , "!definitions"
+                   , "!import"
+                   , "!clear"
+                   , "!save"
+                   , "!reset"
+                   , "!version"
+                   ]
+
+    loop :: Env -> EvaluatedForm -> InputT IO ()
+    loop env form = handle (interruptHandler env form) $ do
       minput <- getInputLine "tricu < "
       case minput of
         Nothing -> outputStrLn "Exiting tricu"
         Just s
-          | strip s == "" -> loop env decode
+          | strip s == "" -> loop env form
           | strip s == "!exit" -> outputStrLn "Exiting tricu"
-          | strip s == "!decode" -> do
+          | strip s == "!clear" -> do
-              outputStrLn $ "Decoding " ++ (if decode then "disabled" else "enabled")
+              liftIO $ putStr "\ESC[2J\ESC[H"
-              loop env (not decode)
+              loop env form
-          | "!import" `isPrefixOf` strip s -> do
+          | strip s == "!reset" -> do
-              let afterImport = dropWhile (== ' ') $ drop (length ("!import" :: String)) (strip s)
+              outputStrLn "Environment reset to initial state"
-              if not (null afterImport)
+              loop Map.empty form
-                then outputStrLn "Warning: REPL imports are interactive; \
+          | strip s == "!version" -> do
-                                  \additional arguments are ignored."
+              outputStrLn $ "tricu version " ++ showVersion version
-                else pure ()
+              loop env form
-              path <- getInputLine "File path to load < "
+          | "!save" `isPrefixOf` strip s -> handleSave env form
-              case path of
+          | strip s == "!output" -> handleOutput env form
-                Nothing -> do
+          | strip s == "!definitions" -> do
-                  outputStrLn "No input received; stopping import."
+              let defs = Map.keys $ Map.delete "!result" env
-                  loop env decode
+              if null defs
-                Just p -> do
+                then outputStrLn "No definitions discovered."
-                  loadedEnv <- liftIO $ evaluateFileWithContext env
+                else do
-                    (strip p) `catch` \e -> errorHandler env e
+                  outputStrLn "Available definitions:"
-                  loop (Map.delete "!result" (Map.union loadedEnv env)) decode
+                  mapM_ outputStrLn defs
-          | take 2 s == "--" -> loop env decode
+              loop env form
+          | "!import" `isPrefixOf` strip s -> handleImport env form
+          | take 2 s == "--" -> loop env form
           | otherwise -> do
-              newEnv <- liftIO $ processInput env s decode `catch` errorHandler env
+              newEnv <- liftIO $ processInput env s form `catch` errorHandler env
-              loop newEnv decode
+              loop newEnv form
 
-    interruptHandler :: Env -> Bool -> Interrupt -> InputT IO ()
+    handleOutput :: Env -> EvaluatedForm -> InputT IO ()
-    interruptHandler env decode _ = do
+    handleOutput env currentForm = do
+      let formats = [Decode, TreeCalculus, FSL, AST, Ternary, Ascii]
+      outputStrLn "Available output formats:"
+      mapM_ (\(i, f) -> outputStrLn $ show i ++ ". " ++ show f)
+        (zip [1..] formats)
+
+      result <- runMaybeT $ do
+        input <- MaybeT $ getInputLine "Select output format (1-6) < "
+        case reads input of
+          [(n, "")] | n >= 1 && n <= 6 ->
+            return $ formats !! (n-1)
+          _ -> MaybeT $ return Nothing
+
+      case result of
+        Nothing -> do
+          outputStrLn "Invalid selection. Keeping current output format."
+          loop env currentForm
+        Just newForm -> do
+          outputStrLn $ "Output format changed to: " ++ show newForm
+          loop env newForm
+
+    handleImport :: Env -> EvaluatedForm -> InputT IO ()
+    handleImport env form = do
+      res <- runMaybeT $ do
+        let fset = setComplete completeFilename defaultSettings
+        path <- MaybeT $ runInputT fset $
+          getInputLineWithInitial "File path to load < " ("", "")
+
+        text <- MaybeT $ liftIO $ handle (\e -> do
+            putStrLn $ "Error reading file: " ++ displayException (e :: IOException)
+            return Nothing
+          ) $ Just <$> readFile (strip path)
+
+        case parseProgram (lexTricu text) of
+          Left err -> do
+            lift $ outputStrLn $ "Parse error: " ++ handleParseError err
+            MaybeT $ return Nothing
+          Right ast -> do
+            ns <- MaybeT $ runInputT defaultSettings $
+              getInputLineWithInitial "Namespace (or !Local for no namespace) < " ("", "")
+
+            let name = strip ns
+            if (name /= "!Local" && (null name || not (isUpper (head name)))) then do
+                lift $ outputStrLn "Namespace must start with an uppercase letter"
+                MaybeT $ return Nothing
+            else do
+                prog <- liftIO $ preprocessFile (strip path)
+                let code = case name of
+                      "!Local" -> prog
+                      _ -> nsDefinitions name prog
+                    env' = evalTricu env code
+                return env'
+      case res of
+        Nothing -> do
+          outputStrLn "Import cancelled"
+          loop env form
+        Just env' ->
+          loop (Map.delete "!result" env') form
+
+    interruptHandler :: Env -> EvaluatedForm -> Interrupt -> InputT IO ()
+    interruptHandler env form _ = do
       outputStrLn "Interrupted with CTRL+C\n\
                   \You can use the !exit command or CTRL+D to exit"
-      loop env decode
+      loop env form
 
-    processInput :: Env -> String -> Bool -> IO Env
+    processInput :: Env -> String -> EvaluatedForm -> IO Env
-    processInput env input decode = do
+    processInput env input form = do
       let asts   = parseTricu input
           newEnv = evalTricu env asts
       case Map.lookup "!result" newEnv of
         Just r -> do
-          putStrLn $ "tricu > " ++ 
+          putStrLn $ "tricu > " ++ formatResult form r
-            if decode 
-              then decodeResult r
-              else show r
         Nothing -> pure ()
       return newEnv
 
@@ -78,3 +164,28 @@ repl env = runInputT defaultSettings (withInterrupt (loop env True))
 
     strip :: String -> String
     strip = dropWhileEnd isSpace . dropWhile isSpace
+
+    handleSave :: Env -> EvaluatedForm -> InputT IO ()
+    handleSave env form = do
+      let fset = setComplete completeFilename defaultSettings
+      path <- runInputT fset $
+        getInputLineWithInitial "File to save < " ("", "")
+
+      case path of
+        Nothing -> do
+          outputStrLn "Save cancelled"
+          loop env form
+        Just p -> do
+          let definitions = Map.toList $ Map.delete "!result" env
+              filepath = strip p
+
+          outputStrLn "Starting save..."
+          liftIO $ writeFile filepath ""
+          outputStrLn "File created..."
+          forM_ definitions $ \(name, value) -> do
+            let content = name ++ " = " ++ formatResult TreeCalculus value ++ "\n"
+            outputStrLn $ "Writing definition: " ++ name ++ " with length " ++ show (length content)
+            liftIO $ appendFile filepath content
+          outputStrLn $ "Saved " ++ show (length definitions) ++ " definitions to " ++ p
+
+          loop env form

src/Research.hs

@@ -1,6 +1,5 @@
 module Research where
 
-import Control.Monad.State
 import Data.List                 (intercalate)
 import Data.Map                  (Map)
 import Data.Text                 (Text, replace)
@@ -55,15 +54,24 @@ data EvaluatedForm = TreeCalculus | FSL | AST | Ternary | Ascii | Decode
 -- Environment containing previously evaluated TC terms
 type Env = Map.Map String T
 
--- Tree Calculus Reduction
+-- Tree Calculus Reduction Rules
+{- 
+  The t operator is left associative.
+  1.  t  t      a b       -> a
+  2.  t (t a)   b c       -> a c (b c)
+  3a. t (t a b) c t       -> a
+  3b. t (t a b) c (t u)   -> b u
+  3c. t (t a b) c (t u v) -> c u v
+-}
 apply :: T -> T -> T
-apply Leaf b                            = Stem b
+apply (Fork Leaf a)         _         = a
-apply (Stem a) b                        = Fork a b
+apply (Fork (Stem a) b) c             = apply (apply a c) (apply b c)
-apply (Fork Leaf a) _                   = a
+apply (Fork (Fork a  b) c)  Leaf      = a
-apply (Fork (Stem a1) a2) b             = apply (apply a1 b) (apply a2 b)
+apply (Fork (Fork a  b) c) (Stem u)   = apply b u
-apply (Fork (Fork a1 a2) a3) Leaf       = a1
+apply (Fork (Fork a  b) c) (Fork u v) = apply (apply c u) v
-apply (Fork (Fork a1 a2) a3) (Stem u)   = apply a2 u
+-- Left associative `t`
-apply (Fork (Fork a1 a2) a3) (Fork u v) = apply (apply a3 u) v
+apply  Leaf b                         = Stem b
+apply (Stem a) b                      = Fork a b
 
 -- Booleans
 _false :: T
@@ -77,7 +85,7 @@ _not = Fork (Fork _true (Fork Leaf _false)) Leaf
 
 -- Marshalling
 ofString :: String -> T
-ofString str = ofList (map ofNumber (map fromEnum str))
+ofString str = ofList $ map (ofNumber . fromEnum) str
 
 ofNumber :: Int -> T
 ofNumber 0 = Leaf
@@ -87,8 +95,7 @@ ofNumber n =
     (ofNumber (n `div` 2))
 
 ofList :: [T] -> T
-ofList [] = Leaf
+ofList = foldr Fork Leaf
-ofList (x:xs) = Fork x (ofList xs)
 
 toNumber :: T -> Either String Int
 toNumber Leaf = Right 0
@@ -126,7 +133,7 @@ toSimpleT s = T.unpack
   $ replace "Fork" "t"
   $ replace "Stem" "t"
   $ replace "Leaf" "t"
-  $ (T.pack s)
+  $ T.pack s
 
 toTernaryString :: T -> String
 toTernaryString Leaf = "0"
@@ -153,8 +160,18 @@ toAscii tree = go tree "" True
         ++ go right (prefix ++ (if isLast then "    " else "|   ")) True
 
 decodeResult :: T -> String
-decodeResult tc
+decodeResult Leaf = "t"
-  | Right num  <- toNumber tc = show num
+decodeResult tc =
-  | Right str  <- toString tc = "\"" ++ str ++ "\""
+  case (toString tc, toList tc, toNumber tc) of
-  | Right list <- toList tc   = "[" ++ intercalate ", " (map decodeResult list) ++ "]"
+    (Right s, _, _) | all isCommonChar s -> "\"" ++ s ++ "\""
-  | otherwise                 = formatResult TreeCalculus tc
+    (_, _, Right n) -> show n
+    (_, Right xs@(_:_), _) -> "[" ++ intercalate ", " (map decodeResult xs) ++ "]"
+    (_, Right [], _) -> "[]"
+    _ -> formatResult TreeCalculus tc
+  where
+    isCommonChar c =
+      let n = fromEnum c
+      in (n >= 32 && n <= 126)
+         || n == 9
+         || n == 10
+         || n == 13

test/Spec.hs

@@ -34,6 +34,7 @@ tests = testGroup "Tricu Tests"
   , fileEval
   , modules
   , demos
+  , decoding
   ]
 
 lexer :: TestTree
@@ -329,18 +330,22 @@ lambdas = testGroup "Lambda Evaluation Tests"
         let input = "f = (\\x : (\\y : x y))\ng = (\\z : z)\nf g t"
         runTricu input @?= "Leaf"
 
-  , testCase "Lambda with a string literal" $ do
+  , testCase "Lambda applied to string literal" $ do
         let input = "f = (\\x : x)\nf \"hello\""
         runTricu input @?= "Fork (Fork Leaf (Fork Leaf (Fork Leaf (Fork (Stem Leaf) (Fork Leaf (Fork (Stem Leaf) (Fork (Stem Leaf) Leaf))))))) (Fork (Fork (Stem Leaf) (Fork Leaf (Fork (Stem Leaf) (Fork Leaf (Fork Leaf (Fork (Stem Leaf) (Fork (Stem Leaf) Leaf))))))) (Fork (Fork Leaf (Fork Leaf (Fork (Stem Leaf) (Fork (Stem Leaf) (Fork Leaf (Fork (Stem Leaf) (Fork (Stem Leaf) Leaf))))))) (Fork (Fork Leaf (Fork Leaf (Fork (Stem Leaf) (Fork (Stem Leaf) (Fork Leaf (Fork (Stem Leaf) (Fork (Stem Leaf) Leaf))))))) (Fork (Fork (Stem Leaf) (Fork (Stem Leaf) (Fork (Stem Leaf) (Fork (Stem Leaf) (Fork Leaf (Fork (Stem Leaf) (Fork (Stem Leaf) Leaf))))))) Leaf))))"
 
 
-   , testCase "Lambda with an integer literal" $ do
+   , testCase "Lambda applied to integer literal" $ do
         let input = "f = (\\x : x)\nf 42"
         runTricu input @?= "Fork Leaf (Fork (Stem Leaf) (Fork Leaf (Fork (Stem Leaf) (Fork Leaf (Fork (Stem Leaf) Leaf)))))"
 
-   , testCase "Lambda with a list literal" $ do
+   , testCase "Lambda applied to list literal" $ do
         let input = "f = (\\x : x)\nf [t (t t)]"
         runTricu input @?= "Fork Leaf (Fork (Stem Leaf) Leaf)"
+
+  , testCase "Lambda containing list literal" $ do
+      let input = "(\\a : [(a)]) 1"
+      runTricu input @?= "Fork (Fork (Stem Leaf) Leaf) Leaf"
   ]
 
 providedLibraries :: TestTree
@@ -518,3 +523,35 @@ demos = testGroup "Test provided demo functionality"
       res     <- liftIO $ evaluateFileResult "./demos/levelOrderTraversal.tri"
       decodeResult res @?= "\"\n1 \n2 3 \n4 5 6 7 \n8 11 10 9 12 \""
   ]
+
+decoding :: TestTree
+decoding = testGroup "Decoding Tests"
+  [ testCase "Decode Leaf" $ do
+      decodeResult Leaf @?= "t"
+
+  , testCase "Decode list of non-ASCII numbers" $ do
+      let input = ofList [ofNumber 1, ofNumber 14, ofNumber 6]
+      decodeResult input @?= "[1, 14, 6]"
+
+  , testCase "Decode list of ASCII numbers as a string" $ do
+      let input = ofList [ofNumber 97, ofNumber 98, ofNumber 99]
+      decodeResult input @?= "\"abc\""
+
+  , testCase "Decode small number" $ do
+      decodeResult (ofNumber 42) @?= "42"
+
+  , testCase "Decode large number" $ do
+      decodeResult (ofNumber 9999) @?= "9999"
+
+  , testCase "Decode string in list" $ do
+      let input = ofList [ofString "hello", ofString "world"]
+      decodeResult input @?= "[\"hello\", \"world\"]"
+
+  , testCase "Decode mixed list with strings" $ do
+      let input = ofList [ofString "hello", ofNumber 42, ofString "world"]
+      decodeResult input @?= "[\"hello\", 42, \"world\"]"
+
+  , testCase "Decode nested lists with strings" $ do
+      let input = ofList [ofList [ofString "nested"], ofString "string"]
+      decodeResult input @?= "[[\"nested\"], \"string\"]"
+  ]

tricu.cabal

@@ -1,7 +1,7 @@
 cabal-version: 1.12
 
 name:           tricu
-version:        0.14.0
+version:        0.18.0
 description:    A micro-language for exploring Tree Calculus
 author:         James Eversole
 maintainer:     james@eversole.co
@@ -32,6 +32,7 @@ executable tricu
     , megaparsec
     , mtl
     , text
+    , transformers
   other-modules:
     Eval
     FileEval
@@ -63,6 +64,7 @@ test-suite tricu-tests
     , tasty-hunit
     , tasty-quickcheck
     , text
+    , transformers
   default-language:    Haskell2010
   other-modules:
     Eval