0.5.0 release commit

Additionally sorts gitignore and adds attempted decoding of lists back
to the REPL

.gitignore

@@ -1,14 +1,11 @@
-bin/
-data/Purr.sqlite
-data/encryptionKey
-/result
-/config.dhall
-/Dockerfile
-/docker-stack.yml
-.stack-work/
 *.swp
-dist*
+*.txt
 *~
 .env
+.stack-work/
+/Dockerfile
+/config.dhall
+/result
 WD
-*.hs.txt
+bin/
+dist*

README.md

@@ -1,18 +1,82 @@
-# sapling
+# tricu
 
-sapling is a "micro-language" that I'm working on to investigate [Tree Calculus](https://github.com/barry-jay-personal/typed_tree_calculus/blob/main/typed_program_analysis.pdf) .
+## Introduction
 
-It offers a minimal amount of syntax sugar:
+tricu (pronounced like "tree-shoe" in English) is a purely functional interpreted language implemented in Haskell. [I'm](https://eversole.co) developing tricu to further research the possibilities offered by the various forms of [Tree Calculi](https://github.com/barry-jay-personal/typed_tree_calculus/blob/main/typed_program_analysis.pdf).
 
-- `t` operator behaving by the rules of Tree Calculus
+tricu offers minimal syntax sugar yet manages to provide a complete, intuitive, and familiar programming environment. There is great power in simplicity. tricu offers:
-- Variable definitions
-- Lambda abstractions
-- List, Integer, and String literals
 
-This is an active experimentation project by [someone who has no idea what they're doing](https://eversole.co).
+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 for grouping function application
+
+These 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.
+
+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.
+
+## What does it look like?
+
+```
+tricu < -- Anything after `--` on a single line is a comment
+tricu < id = (\a : a) -- Lambda abstraction is eliminated to tree calculus terms
+tricu < head (map (\i : lconcat i " world!") [("Hello, ")])
+tricu > "Hello,  world!"
+tricu < id (head (map (\i : lconcat i " world!") [("Hello, ")]))
+tricu > "Hello,  world!"
+
+tricu < -- Intensionality! We can inspect the structure of a function.
+tricu < triage = (\a b c : t (t a b) c)
+tricu < test = triage "Leaf" (\z : "Stem") (\a b : "Fork")
+tricu < test t t
+tricu > "Stem"
+tricu < -- We can even write a function to convert a function to source code
+tricu < toTString id
+tricu > "t (t (t t)) t"
+```
+
+## Installation and Use
+
+You can easily build and/or run this project using [Nix](https://nixos.org/download/).
+
+- Quick Start (REPL): 
+  - `nix run git+https://git.eversole.co/James/tricu`
+- Build executable in `./result/bin`: 
+  - `nix build git+https://git.eversole.co/James/tricu`
+
+`./result/bin/tricu --help`
+
+```
+tricu Evaluator and REPL
+
+tricu [COMMAND] ... [OPTIONS]
+  tricu: Exploring Tree Calculus
+
+Common flags:
+  -? --help       Display help message
+  -V --version    Print version information
+
+tricu [repl] [OPTIONS]
+  Start interactive REPL
+
+tricu eval [OPTIONS]
+  Evaluate tricu and return the result of the final expression.
+
+  -f --file=FILE  Input file path(s) for evaluation.
+                    Defaults to stdin.
+  -t --form=FORM  Optional output form: (tree|fsl|ast|ternary|ascii).
+                    Defaults to tricu-compatible `t` tree form.
+
+tricu decode [OPTIONS]
+  Decode a Tree Calculus value into a string representation.
+
+  -f --file=FILE  Optional input file path to attempt decoding.
+                    Defaults to stdin.
+```
 
 ## Acknowledgements 
 
 Tree Calculus was discovered by [Barry Jay](https://github.com/barry-jay-personal/blog). 
 
-[treecalcul.us](https://treecalcul.us) is an excellent website with an intuitive playground created by [Johannes Bader](https://johannes-bader.com/) that introduced me to Tree Calculus. If sapling sounds interesting but compiling this repo sounds like a hassle, you should check out his site.
+[treecalcul.us](https://treecalcul.us) is an excellent website with an intuitive playground created by [Johannes Bader](https://johannes-bader.com/) that introduced me to Tree Calculus. If tricu sounds interesting but compiling this repo sounds like a hassle, you should check out his site.

demos/LevelOrderTraversal.tri

@@ -0,0 +1,34 @@
+-- Level Order Traversal of a labelled binary tree
+-- Objective: Print each "level" of the tree on a separate line
+--
+-- NOTICE: This demo relies on tricu base library functions
+-- 
+-- We model labelled binary trees as sublists where values act as labels. We
+-- require explicit notation of empty nodes. Empty nodes can be represented 
+-- with an empty list, `[]`, which is equivalent to a single node `t`. 
+--
+-- Example tree inputs:
+-- [("1") [("2") [("4") t t] t] [("3") [("5") t t] [("6") t t]]]]
+-- Graph:
+--       1
+--      / \
+--     2   3
+--    /   /  \
+--   4   5    6
+--
+
+isLeaf = (\node : lOr (emptyList node) (emptyList (tail node)))
+getLabel = (\node : head node)
+getLeft = (\node : if (emptyList node) [] (if (emptyList (tail node)) [] (head (tail node))))
+getRight = (\node : if (emptyList node) [] (if (emptyList (tail node)) [] (if (emptyList (tail (tail node))) [] (head (tail (tail node))))))
+
+processLevel = y (\self queue : if (emptyList queue) [] (pair (map getLabel queue) (self (filter (\node : not (emptyList node)) (lconcat (map getLeft queue) (map getRight queue))))))
+levelOrderTraversal = (\a : processLevel (t a t))
+toLineString = y (\self levels : if (emptyList levels) "" (lconcat (lconcat (map (\x : lconcat x " ") (head levels)) "") (if (emptyList (tail levels)) "" (lconcat (t (t 10 t) t) (self (tail levels))))))
+levelOrderToString = (\s : toLineString (levelOrderTraversal s))
+
+flatten = foldl (\acc x : lconcat acc x) ""
+flatLOT = (\s : lconcat (t 10 t) (flatten (levelOrderToString s)))
+
+exampleOne = flatLOT [("1") [("2") [("4") t t] t] [("3") [("5") t t] [("6") t t]]]]
+exampleTwo = flatLOT [("1") [("2") [("4") [("8") t t] [("9") t t]] [("6") [("10") t t] [("12") t t]]] [("3") [("5") [("11") t t] t] [("7") t t]]]

flake.nix

@@ -1,5 +1,5 @@
 {
-  description = "sapling";
+  description = "tricu";
 
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs";
@@ -10,7 +10,7 @@
     flake-utils.lib.eachDefaultSystem (system:
       let
         pkgs              = nixpkgs.legacyPackages.${system};
-        packageName       = "sapling";
+        packageName       = "tricu";
         containerPackageName = "${packageName}-container";
 
         customGHC = pkgs.haskellPackages.ghcWithPackages (hpkgs: with hpkgs; [
@@ -22,7 +22,7 @@
         enableSharedExecutables = false;
         enableSharedLibraries = false;
 
-        sapling = pkgs.haskell.lib.justStaticExecutables self.packages.${system}.default;
+        tricu = pkgs.haskell.lib.justStaticExecutables self.packages.${system}.default;
       in {
 
         packages.${packageName} =

lib/base.tri

@@ -0,0 +1,41 @@
+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)
+iC = (\a b c : s a (k c) b)
+iD = b (b iC) iC
+iE = b (b iD) iC
+yi = (\i : b m (c b (i m)))
+y = yi iC
+yC = yi iD
+yD = yi iE
+id = (\a : a)
+triage = (\a b c : t (t a b) c)
+pair = t
+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")
+emptyList = matchList true (\y z : false)
+head = matchList t (\hd tl : hd)
+tail = matchList t (\hd tl : tl)
+lconcat = 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)
+hmap = y (\self : matchList (\f : t) (\hd tl f : pair (f hd) (self tl f)))
+map = (\f l : hmap l f)
+equal = y (\self : triage (triage true (\z : false) (\y z : false)) (\ax : triage false (self ax) (\y z : false)) (\ax ay : triage false (\z : false) (\bx by : lAnd (self ax bx) (self ay by))))
+hfilter = y (\self : matchList (\f : t) (\hd tl f : matchBool (t hd) i (f hd) (self tl f)))
+filter = (\f l : hfilter l f)
+hfoldl = y (\self f l x : matchList (\acc : acc) (\hd tl acc : self f tl (f acc hd)) l x)
+foldl  = (\f x l : hfoldl f l x)
+hfoldr = y (\self x f l : matchList x (\hd tl : f (self x f tl) hd) l)
+foldr  = (\f x l : hfoldr x f l)

shell.nix

@@ -1,8 +0,0 @@
-{ pkgs ? import <nixpkgs> {} }:
-let x = pkgs.haskellPackages.ghcWithPackages (hpkgs: with hpkgs; [
-		megaparsec
-  ]);
-in
-pkgs.mkShell {
-  buildInputs = [ x ];
-}

src/Eval.hs

@@ -2,139 +2,116 @@ module Eval where
 
 import Parser
 import Research
-import Data.Set (Set)
+
-import qualified Data.Set as Set
+import Data.Map  (Map)
-import Data.List (foldl')
+
 import qualified Data.Map as Map
-import Data.Map (Map)
+import qualified Data.Set as Set
 
-evalSingle :: Map.Map String T -> SaplingAST -> Map.Map String T
+evalSingle :: Map String T -> TricuAST -> Map String T
 evalSingle env term = case term of
-    SFunc name [] body ->
+  SFunc name [] body ->
-        let result = evalAST env body
+    let lineNoLambda = eliminateLambda body
-        in Map.insert name result env
+        result = evalAST env lineNoLambda
-    SApp func arg ->
+    in Map.insert "__result" result (Map.insert name result env)
-        let result = apply (evalAST env func) (evalAST env arg)
+  SLambda _ body ->
-        in Map.insert "__result" result env
+    let result = evalAST env body
-    SVar name -> case Map.lookup name env of
+    in Map.insert "__result" result env
-        Just value -> Map.insert "__result" value env
+  SApp func arg ->
-        Nothing -> error $ "Variable " ++ name ++ " not defined"
+    let result = apply (evalAST env $ eliminateLambda func) (evalAST env $ eliminateLambda arg)
-    _ ->
+    in Map.insert "__result" result env
-        let result = evalAST env term
+  SVar name ->
-        in Map.insert "__result" result env
+    case Map.lookup name env of
+      Just value -> Map.insert "__result" value env
+      Nothing -> errorWithoutStackTrace $ "Variable " ++ name ++ " not defined"
+  _ ->
+    let result = evalAST env term
+    in Map.insert "__result" result env
 
-evalSapling :: Map String T -> [SaplingAST] -> Map String T
+evalTricu :: Map String T -> [TricuAST] -> Map String T
-evalSapling env [] = env
+evalTricu env list = evalTricu' env (filter (/= SEmpty) list)
-evalSapling env [lastLine] =
+  where
-    let
+  evalTricu' :: Map String T -> [TricuAST] -> Map String T
-        lastLineNoLambda = eliminateLambda lastLine
+  evalTricu' env [] = env
+  evalTricu' env [lastLine] =
+    let lastLineNoLambda = eliminateLambda lastLine
         updatedEnv = evalSingle env lastLineNoLambda
     in Map.insert "__result" (result updatedEnv) updatedEnv
-evalSapling env (line:rest) =
+  evalTricu' env (line:rest) =
-    let
+    let lineNoLambda = eliminateLambda line
-        lineNoLambda = eliminateLambda line
         updatedEnv = evalSingle env lineNoLambda
-    in evalSapling updatedEnv rest
+    in evalTricu updatedEnv rest
 
-evalAST :: Map String T -> SaplingAST -> T
+evalAST :: Map String T -> TricuAST -> T
 evalAST env term = case term of
-    SVar name ->
+  SVar name -> case Map.lookup name env of
-        case Map.lookup name env of
+    Just value -> value
-            Just value -> value
+    Nothing -> errorWithoutStackTrace $ "Variable " ++ name ++ " not defined"
-            Nothing -> error $ "Variable " ++ name ++ " not defined"
+  TLeaf -> Leaf
-    TLeaf -> Leaf
+  TStem t -> Stem (evalAST env t)
-    TStem t ->
+  TFork t1 t2 -> Fork (evalAST env t1) (evalAST env t2)
-        Stem (evalAST env t)
+  SApp t1 t2 -> apply (evalAST env t1) (evalAST env t2)
-    TFork t1 t2 ->
+  SStr str -> ofString str
-        Fork (evalAST env t1) (evalAST env t2)
+  SInt num -> ofNumber num
-    SApp t1 t2 ->
+  SList elems -> ofList (map (evalAST env) elems)
-        apply (evalAST env t1) (evalAST env t2)
+  SEmpty -> Leaf
-    SStr str -> toString str
+  SFunc name args body ->
-    SInt num -> toNumber num
+    errorWithoutStackTrace $ "Unexpected function definition " ++ name
-    SList elems -> toList (map (evalAST Map.empty) elems)
+  SLambda {} -> errorWithoutStackTrace "Internal error: SLambda found in evalAST after elimination."
-    SFunc name args body ->
-        error $ "Unexpected function definition " ++ name
-        ++ " in evalAST; define via evalSingle."
-    SLambda {} ->
-        error "Internal error: SLambda found in evalAST after elimination."
 
-result :: Map String T -> T
+eliminateLambda :: TricuAST -> TricuAST
-result r = case Map.lookup "__result" r of
-    Just a -> a
-    Nothing -> error "No __result field found in provided environment"
-
-
-eliminateLambda :: SaplingAST -> SaplingAST
 eliminateLambda (SLambda (v:vs) body)
-    | null vs = lambdaToT v (eliminateLambda body)
+  | null vs = lambdaToT v (eliminateLambda body)
-    | otherwise =
+  | otherwise = eliminateLambda (SLambda [v] (SLambda vs body))
-        eliminateLambda (SLambda [v] (SLambda vs body))
+eliminateLambda (SApp f arg) = SApp (eliminateLambda f) (eliminateLambda arg)
-eliminateLambda (SApp f arg) =
+eliminateLambda (TStem t) = TStem (eliminateLambda t)
-    SApp (eliminateLambda f) (eliminateLambda arg)
+eliminateLambda (TFork l r) = TFork (eliminateLambda l) (eliminateLambda r)
-eliminateLambda (TStem t) =
+eliminateLambda (SList xs) = SList (map eliminateLambda xs)
-    TStem (eliminateLambda t)
-eliminateLambda (TFork l r) =
-    TFork (eliminateLambda l) (eliminateLambda r)
-eliminateLambda (SList xs) =
-    SList (map eliminateLambda xs)
-eliminateLambda (SFunc n vs b) =
-    SFunc n vs (eliminateLambda b)
 eliminateLambda other = other
 
-lambdaToT :: String -> SaplingAST -> SaplingAST
+-- https://github.com/barry-jay-personal/typed_tree_calculus/blob/main/typed_program_analysis.pdf
+-- Chapter 4: Lambda-Abstraction
+lambdaToT :: String -> TricuAST -> TricuAST
 lambdaToT x (SVar y)
-    | x == y = tI
+  | x == y = tI
 lambdaToT x (SVar y)
-    | x /= y =
+  | x /= y = SApp tK (SVar y)
-        SApp tK (SVar y)
 lambdaToT x t
-    | not (isFree x t) =
+  | not (isFree x t) = SApp tK t
-        SApp tK t
 lambdaToT x (SApp n u)
-    | not (isFree x (SApp n u)) =
+  | not (isFree x (SApp n u)) = SApp tK (SApp (eliminateLambda n) (eliminateLambda u))
-        SApp tK (SApp (eliminateLambda n) (eliminateLambda u))
+lambdaToT x (SApp n u) = SApp (SApp tS (lambdaToT x (eliminateLambda n))) (lambdaToT x (eliminateLambda u))
-lambdaToT x (SApp n u) =
-    SApp
-    (SApp tS (lambdaToT x (eliminateLambda n)))
-    (lambdaToT x (eliminateLambda u))
-lambdaToT x (SApp f args) = lambdaToT x f
 lambdaToT x body
-    | not (isFree x body) =
+  | not (isFree x body) = SApp tK body
-        SApp tK body
+  | otherwise = SApp (SApp tS (lambdaToT x body)) TLeaf
-    | otherwise =
-        SApp
-        (SApp tS (lambdaToT x body))
-        tLeaf
 
-tLeaf :: SaplingAST
+freeVars :: TricuAST -> Set.Set String
-tLeaf = TLeaf
-
-freeVars :: SaplingAST -> Set String
 freeVars (SVar v) = Set.singleton v
 freeVars (SInt _) = Set.empty
 freeVars (SStr _) = Set.empty
 freeVars (SList xs) = foldMap freeVars xs
-freeVars (SFunc _ _ b) = freeVars b
 freeVars (SApp f arg) = freeVars f <> freeVars arg
 freeVars TLeaf = Set.empty
+freeVars (SFunc _ _ b) = freeVars b
 freeVars (TStem t) = freeVars t
 freeVars (TFork l r) = freeVars l <> freeVars r
 freeVars (SLambda vs b) = foldr Set.delete (freeVars b) vs
 
-isFree :: String -> SaplingAST -> Bool
+isFree :: String -> TricuAST -> Bool
 isFree x = Set.member x . freeVars
 
-toAST :: T -> SaplingAST
+-- We need the SKI operators in an unevaluated TricuAST tree form so that we
-toAST Leaf = TLeaf
+-- can keep the evaluation functions straightforward
-toAST (Stem a) = TStem (toAST a)
+tI :: TricuAST
-toAST (Fork a b) = TFork (toAST a) (toAST b)
+tI = SApp (SApp TLeaf (SApp TLeaf (SApp TLeaf TLeaf))) TLeaf
 
-tI :: SaplingAST
+tK :: TricuAST
-tI = toAST _I
+tK = SApp TLeaf TLeaf
 
-tK :: SaplingAST
+tS :: TricuAST
-tK = toAST _K
+tS = SApp (SApp TLeaf (SApp TLeaf (SApp (SApp TLeaf TLeaf) TLeaf))) TLeaf
-
-tS :: SaplingAST
-tS = toAST _S
 
+result :: Map String T -> T
+result r = case Map.lookup "__result" r of
+  Just a -> a
+  Nothing -> errorWithoutStackTrace "No __result field found in provided environment"

src/FileEval.hs

@@ -0,0 +1,30 @@
+module FileEval where
+
+import Eval
+import Parser
+import Research
+
+import System.IO
+
+import qualified Data.Map as Map
+
+evaluateFileResult :: FilePath -> IO T
+evaluateFileResult filePath = do
+  contents <- readFile filePath
+  let asts = parseTricu contents
+  let finalEnv = evalTricu Map.empty asts
+  case Map.lookup "__result" finalEnv of
+    Just finalResult -> return finalResult
+    Nothing -> errorWithoutStackTrace "No expressions to evaluate found"
+
+evaluateFile :: FilePath -> IO Env
+evaluateFile filePath = do
+  contents <- readFile filePath
+  let asts = parseTricu contents
+  pure $ evalTricu Map.empty asts
+
+evaluateFileWithContext :: Env -> FilePath -> IO Env
+evaluateFileWithContext env filePath = do
+  contents <- readFile filePath
+  let asts = parseTricu contents
+  pure $ evalTricu env asts

src/Lexer.hs

@@ -1,33 +1,25 @@
 module Lexer where
 
 import Research
-import Text.Megaparsec
+
-import Text.Megaparsec.Char
+import Control.Monad               (void)
 import Data.Void
+import Text.Megaparsec
+import Text.Megaparsec.Char hiding (space)
+import Text.Megaparsec.Char.Lexer
+
 import qualified Data.Set as Set
 
 type Lexer = Parsec Void String
-data LToken
-  = LKeywordT
-  | LIdentifier String
-  | LIntegerLiteral Int
-  | LStringLiteral String
-  | LAssign
-  | LColon
-  | LBackslash
-  | LOpenParen
-  | LCloseParen
-  | LOpenBracket
-  | LCloseBracket
-  | LNewline
-  deriving (Show, Eq, Ord)
 
 keywordT :: Lexer LToken
 keywordT = string "t" *> notFollowedBy alphaNumChar *> pure LKeywordT
 
 identifier :: Lexer LToken
 identifier = do
-  name <- some (letterChar <|> char '_' <|> char '-')
+  first <- letterChar <|> char '_'
+  rest <- many (letterChar <|> char '_' <|> char '-' <|> digitChar)
+  let name = first : rest
   if (name == "t" || name == "__result")
     then fail "Keywords (`t`, `__result`) cannot be used as an identifier"
     else return (LIdentifier name)
@@ -41,11 +33,8 @@ stringLiteral :: Lexer LToken
 stringLiteral = do
   char '"'
   content <- many (noneOf ['"'])
-  if null content
+  char '"' --"
-    then fail "Empty string literals are not allowed"
+  return (LStringLiteral content)
-    else do
-      char '"' -- "
-      return (LStringLiteral content)
 
 assign :: Lexer LToken
 assign = char '=' *> pure LAssign
@@ -72,25 +61,34 @@ lnewline :: Lexer LToken
 lnewline = char '\n' *> pure LNewline
 
 sc :: Lexer ()
-sc = skipMany (char ' ' <|> char '\t')
+sc = space space1 (skipLineComment "--") (skipBlockComment "|-" "-|")
 
-saplingLexer :: Lexer [LToken]
+tricuLexer :: Lexer [LToken]
-saplingLexer = many (sc *> choice
+tricuLexer = do
-  [ try identifier
+  sc
-  , try keywordT
+  tokens <- many $ do
-  , try integerLiteral
+    tok <- choice tricuLexer'
-  , try stringLiteral
+    sc
-  , assign
+    pure tok
-  , colon
+  sc
-  , backslash
+  eof
-  , openParen
+  pure tokens
-  , closeParen
+    where
-  , openBracket
+      tricuLexer' = 
-  , closeBracket
+        [ try identifier
-  , lnewline
+        , try keywordT
-  ] <* sc) <* eof
+        , try integerLiteral
+        , try stringLiteral
+        , assign
+        , colon
+        , backslash
+        , openParen
+        , closeParen
+        , openBracket
+        , closeBracket
+        ]
 
-lexSapling :: String -> [LToken]
+lexTricu :: String -> [LToken]
-lexSapling input = case runParser saplingLexer "" input of
+lexTricu input = case runParser tricuLexer "" input of
-  Left err  -> error $ "Lexical error:\n" ++ errorBundlePretty err
+  Left err -> errorWithoutStackTrace $ "Lexical error:\n" ++ errorBundlePretty err
   Right tokens -> tokens

src/Main.hs

@@ -1,13 +1,84 @@
 module Main where
 
-import Eval
+import Eval                   (evalTricu, result)
-import Lexer
+import FileEval
-import Parser
+import Parser                 (parseTricu)
-import REPL (repl)
+import REPL
 import Research
 
+import Control.Monad          (foldM)
+import Control.Monad.IO.Class (liftIO)
+import Text.Megaparsec        (runParser)
+import System.Console.CmdArgs
+
 import qualified Data.Map as Map
-import Text.Megaparsec (runParser)
+
+data TricuArgs
+  = Repl
+  | Evaluate { file :: [FilePath], form :: EvaluatedForm }
+  | Decode { file :: [FilePath] }
+  deriving (Show, Data, Typeable)
+
+replMode :: TricuArgs
+replMode = Repl
+  &= help "Start interactive REPL"
+  &= auto
+  &= name "repl"
+
+evaluateMode :: TricuArgs
+evaluateMode = Evaluate
+  { file = def &= help "Input file path(s) for evaluation.\n \
+      \ Defaults to stdin."
+      &= name "f" &= typ "FILE"
+    , form = TreeCalculus &= typ "FORM"
+      &= help "Optional output form: (tree|fsl|ast|ternary|ascii).\n \
+      \ Defaults to tricu-compatible `t` tree form."
+      &= name "t"
+  }
+  &= help "Evaluate tricu and return the result of the final expression."
+  &= explicit
+  &= name "eval"
+
+decodeMode :: TricuArgs
+decodeMode = Decode
+  { file = def
+    &= help "Optional input file path to attempt decoding.\n \
+    \ Defaults to stdin."
+    &= name "f" &= typ "FILE"
+  }
+  &= help "Decode a Tree Calculus value into a string representation."
+  &= explicit
+  &= name "decode"
 
 main :: IO ()
-main = repl Map.empty --(Map.fromList [("__result", Leaf)])
+main = do
+  args <- cmdArgs $ modes [replMode, evaluateMode, decodeMode]
+    &= help "tricu: Exploring Tree Calculus"
+    &= program "tricu"
+    &= 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.`"
+      library <- liftIO $ evaluateFile "./lib/base.tri"
+      repl $ Map.delete "__result" library
+    Evaluate { file = filePaths, form = form } -> do
+      result <- case filePaths of
+        [] -> do
+          t <- getContents
+          pure $ runTricu t
+        (filePath:restFilePaths) -> do
+            initialEnv <- evaluateFile filePath
+            finalEnv <- foldM evaluateFileWithContext initialEnv restFilePaths
+            pure $ result finalEnv
+      let fRes = formatResult form result
+      putStr fRes
+    Decode { file = filePaths } -> do
+      value <- case filePaths of
+        [] -> getContents
+        (filePath:_) -> readFile filePath
+      library <- liftIO $ evaluateFile "./lib/base.tri"
+      putStrLn $ decodeResult $ result $ evalTricu library $ parseTricu value
+
+runTricu :: String -> T
+runTricu = result . evalTricu Map.empty . parseTricu

src/Parser.hs

@@ -1,57 +1,50 @@
 module Parser where
 
-import Debug.Trace
-
 import Lexer
-import Research hiding (toList)
+import Research hiding       (toList)
 
-import Control.Exception (throw)
+import Data.List.NonEmpty    (toList)
-import Data.List.NonEmpty (toList)
+import Data.Void (Void)
-import qualified Data.Set as Set
-import Data.Void
 import Text.Megaparsec
 import Text.Megaparsec.Char
-import Text.Megaparsec.Error (errorBundlePretty, ParseErrorBundle)
+import Text.Megaparsec.Error (ParseErrorBundle, errorBundlePretty)
 
-type Parser = Parsec Void [LToken]
+import qualified Data.Set as Set
-data SaplingAST
-  = SVar    String
-  | SInt    Int
-  | SStr    String
-  | SList   [SaplingAST]
-  | SFunc   String       [String]     SaplingAST
-  | SApp    SaplingAST   SaplingAST
-  | TLeaf
-  | TStem   SaplingAST
-  | TFork   SaplingAST   SaplingAST
-  | SLambda [String]     SaplingAST
-  deriving (Show, Eq, Ord)
 
-parseSapling :: String -> [SaplingAST]
+type Parser    = Parsec Void [LToken]
-parseSapling input =
+type AltParser = Parsec Void String
-  let nonEmptyLines = filter (not . null) (lines input)
-  in map parseSingle nonEmptyLines
 
-parseSingle :: String -> SaplingAST
+parseTricu :: String -> [TricuAST]
-parseSingle "" = error "Empty input provided to parseSingle"
+parseTricu input
-parseSingle input = case runParser parseExpression "" (lexSapling input) of
+  | null tokens = []
-  Left  err -> error $ handleParseError err
+  | otherwise = map parseSingle tokens
-  Right ast -> ast
+  where
+    tokens = case lexTricu input of
+      [] -> []
+      tokens -> lines input
 
-scnParser :: Parser ()
+parseSingle :: String -> TricuAST
-scnParser = skipMany (satisfy isNewline)
+parseSingle input = case lexTricu input of
+  [] -> SEmpty
+  tokens -> case runParser parseExpression "" tokens of
+    Left err -> error $ handleParseError err
+    Right ast -> ast
 
-parseExpression :: Parser SaplingAST
+parseExpression :: Parser TricuAST
 parseExpression = choice
   [ try parseFunction
   , try parseLambda
+  , try parseLambdaExpression
   , try parseListLiteral
   , try parseApplication
   , try parseTreeTerm
   , parseLiteral
   ]
 
-parseFunction :: Parser SaplingAST
+scnParser :: Parser ()
+scnParser = skipMany (satisfy isNewline)
+
+parseFunction :: Parser TricuAST
 parseFunction = do
   LIdentifier name <- satisfy isIdentifier
   args <- many (satisfy isIdentifier)
@@ -59,86 +52,86 @@ parseFunction = do
   body <- parseExpression
   return (SFunc name (map getIdentifier args) body)
 
-parseLambda :: Parser SaplingAST
+parseAtomicBase :: Parser TricuAST
+parseAtomicBase = choice
+    [ parseTreeLeaf
+    , parseGrouped
+    ]
+
+parseLambda :: Parser TricuAST
 parseLambda = between (satisfy (== LOpenParen)) (satisfy (== LCloseParen)) $ do
   satisfy (== LBackslash)
-  param <- satisfy isIdentifier
+  param    <- satisfy isIdentifier
-  rest <- many (satisfy isIdentifier)
+  rest     <- many (satisfy isIdentifier)
   satisfy (== LColon)
-  body <- parseLambdaExpression
+  body     <- parseLambdaExpression
   let nestedLambda = foldr (\v acc -> SLambda [v] acc) body (map getIdentifier rest)
   return (SLambda [getIdentifier param] nestedLambda)
 
-parseLambdaExpression :: Parser SaplingAST
+parseLambdaExpression :: Parser TricuAST
 parseLambdaExpression = choice
   [ try parseLambdaApplication
   , parseAtomicLambda
   ]
 
-parseAtomicLambda :: Parser SaplingAST
+parseAtomicLambda :: Parser TricuAST
 parseAtomicLambda = choice
   [ parseVar
   , parseTreeLeaf
   , parseLiteral
   , parseListLiteral
+  , try parseLambda
   , between (satisfy (== LOpenParen)) (satisfy (== LCloseParen)) parseLambdaExpression
   ]
 
-parseApplication :: Parser SaplingAST
+parseApplication :: Parser TricuAST
 parseApplication = do
   func <- parseAtomicBase
   args <- many parseAtomic
   return $ foldl (\acc arg -> SApp acc arg) func args
 
-parseLambdaApplication :: Parser SaplingAST
+parseLambdaApplication :: Parser TricuAST
 parseLambdaApplication = do
-    func <- parseAtomicLambda
+  func <- parseAtomicLambda
-    args <- many parseAtomicLambda
+  args <- many parseAtomicLambda
-    return $ foldl (\acc arg -> SApp acc arg) func args
+  return $ foldl (\acc arg -> SApp acc arg) func args
 
-isTreeTerm :: SaplingAST -> Bool
+isTreeTerm :: TricuAST -> Bool
-isTreeTerm TLeaf       = True
+isTreeTerm TLeaf = True
-isTreeTerm (TStem _)   = True
+isTreeTerm (TStem _) = True
 isTreeTerm (TFork _ _) = True
-isTreeTerm _           = False
+isTreeTerm _ = False
 
-parseAtomicBase :: Parser SaplingAST
+parseTreeLeaf :: Parser TricuAST
-parseAtomicBase = choice
-  [ parseVar
-  , parseTreeLeaf
-  , parseGrouped
-  ]
-
-parseTreeLeaf :: Parser SaplingAST
 parseTreeLeaf = satisfy isKeywordT *> notFollowedBy (satisfy (== LAssign)) *> pure TLeaf
 
 getIdentifier :: LToken -> String
 getIdentifier (LIdentifier name) = name
 getIdentifier _ = error "Expected identifier"
 
-parseTreeTerm :: Parser SaplingAST
+parseTreeTerm :: Parser TricuAST
 parseTreeTerm = do
   base <- parseTreeLeafOrParenthesized
   rest <- many parseTreeLeafOrParenthesized
   pure $ foldl combine base rest
   where
     combine acc next = case acc of
-      TLeaf     -> TStem next
+      TLeaf -> TStem next
-      TStem t   -> TFork t next
+      TStem t -> TFork t next
       TFork _ _ -> TFork acc next
 
-parseTreeLeafOrParenthesized :: Parser SaplingAST
+parseTreeLeafOrParenthesized :: Parser TricuAST
 parseTreeLeafOrParenthesized = choice
   [ between (satisfy (== LOpenParen)) (satisfy (== LCloseParen)) parseTreeTerm
   , parseTreeLeaf
   ]
 
-foldTree :: [SaplingAST] -> SaplingAST
+foldTree :: [TricuAST] -> TricuAST
 foldTree [] = TLeaf
 foldTree [x] = x
 foldTree (x:y:rest) = TFork x (foldTree (y:rest))
 
-parseAtomic :: Parser SaplingAST
+parseAtomic :: Parser TricuAST
 parseAtomic = choice
   [ parseVar
   , parseTreeLeaf
@@ -147,93 +140,123 @@ parseAtomic = choice
   , parseLiteral
   ]
 
-
+parseGrouped :: Parser TricuAST
-parseGrouped :: Parser SaplingAST
 parseGrouped = between (satisfy (== LOpenParen)) (satisfy (== LCloseParen)) parseExpression
 
-parseLiteral :: Parser SaplingAST
+parseLiteral :: Parser TricuAST
 parseLiteral = choice
   [ parseIntLiteral
   , parseStrLiteral
   ]
 
-parens :: Parser SaplingAST -> Parser SaplingAST
+parens :: Parser TricuAST -> Parser TricuAST
 parens p = do
   satisfy (== LOpenParen)
   result <- p
   satisfy (== LCloseParen)
   return result
 
-parseListLiteral :: Parser SaplingAST
+parseListLiteral :: Parser TricuAST
 parseListLiteral = do
   satisfy (== LOpenBracket)
   elements <- many parseListItem
   satisfy (== LCloseBracket)
   return (SList elements)
 
-parseListItem :: Parser SaplingAST
+parseListItem :: Parser TricuAST
 parseListItem = choice
   [ parseGroupedItem
   , parseListLiteral
   , parseSingleItem
   ]
 
-parseGroupedItem :: Parser SaplingAST
+parseGroupedItem :: Parser TricuAST
 parseGroupedItem = do
   satisfy (== LOpenParen)
   inner <- parseExpression
   satisfy (== LCloseParen)
   return inner
 
-parseSingleItem :: Parser SaplingAST
+parseSingleItem :: Parser TricuAST
 parseSingleItem = do
   token <- satisfy isListItem
   case token of
     LIdentifier name -> return (SVar name)
-    LKeywordT        -> return TLeaf
+    LKeywordT -> return TLeaf
-    _                -> fail "Unexpected token in list item"
+    _ -> fail "Unexpected token in list item"
 
 isListItem :: LToken -> Bool
 isListItem (LIdentifier _) = True
 isListItem LKeywordT = True
 isListItem _ = False
 
-parseVar :: Parser SaplingAST
+parseVar :: Parser TricuAST
 parseVar = do
   LIdentifier name <- satisfy isIdentifier
   if (name == "t" || name == "__result")
     then fail $ "Reserved keyword: " ++ name ++ " cannot be assigned."
     else return (SVar name)
 
-parseIntLiteral :: Parser SaplingAST
+parseIntLiteral :: Parser TricuAST
 parseIntLiteral = do
   LIntegerLiteral value <- satisfy isIntegerLiteral
   return (SInt value)
 
-parseStrLiteral :: Parser SaplingAST
+parseStrLiteral :: Parser TricuAST
 parseStrLiteral = do
   LStringLiteral value <- satisfy isStringLiteral
   return (SStr value)
 
 -- Boolean Helpers
-isKeywordT       (LKeywordT)         = True
+isKeywordT (LKeywordT) = True
-isKeywordT                        _  = False
+isKeywordT _ = False
-
+isIdentifier (LIdentifier _) = True
-isIdentifier     (LIdentifier     _) = True
+isIdentifier _ = False
-isIdentifier                      _  = False
-
 isIntegerLiteral (LIntegerLiteral _) = True
-isIntegerLiteral                  _  = False
+isIntegerLiteral _ = False
+isStringLiteral (LStringLiteral _) = True
+isStringLiteral _ = False
+isLiteral (LIntegerLiteral _) = True
+isLiteral (LStringLiteral _) = True
+isLiteral _ = False
+isNewline (LNewline) = True
+isNewline _ = False
 
-isStringLiteral  (LStringLiteral  _) = True
+-- Alternative parsers
-isStringLiteral                   _  = False
+altSC :: AltParser ()
+altSC = skipMany (char ' ' <|> char '\t' <|> char '\n')
 
-isLiteral        (LIntegerLiteral _) = True
+parseTernaryTerm :: AltParser TricuAST
-isLiteral        (LStringLiteral  _) = True
+parseTernaryTerm = do
-isLiteral                         _  = False
+  altSC
+  term <- choice parseTernaryTerm'
+  altSC
+  pure term
+  where
+    parseTernaryTerm' =
+      [ try (between (char '(') (char ')') parseTernaryTerm)
+      , try parseTernaryLeaf
+      , try parseTernaryStem
+      , try parseTernaryFork
+      ]
 
-esNewline        (LNewline)          = True
+parseTernaryLeaf :: AltParser TricuAST
-isNewline                         _  = False
+parseTernaryLeaf = char '0' *> pure TLeaf
+
+parseTernaryStem :: AltParser TricuAST
+parseTernaryStem = char '1' *> (TStem <$> parseTernaryTerm)
+
+parseTernaryFork :: AltParser TricuAST
+parseTernaryFork = do
+  char '2'
+  term1 <- parseTernaryTerm
+  term2 <- parseTernaryTerm
+  pure $ TFork term1 term2
+
+parseTernary :: String -> Either String TricuAST
+parseTernary input = case runParser (parseTernaryTerm <* eof) "" input of
+  Left err -> Left (errorBundlePretty err)
+  Right ast -> Right ast
 
 -- Error Handling
 handleParseError :: ParseErrorBundle [LToken] Void -> String
@@ -246,9 +269,9 @@ handleParseError bundle =
 showError :: ParseError [LToken] Void -> String
 showError (TrivialError offset (Just (Tokens tokenStream)) expected) =
   "Parse error at offset " ++ show offset ++ ": unexpected token "
-    ++ show tokenStream ++ ", expected one of " ++ show (Set.toList expected)
+  ++ show tokenStream ++ ", expected one of " ++ show (Set.toList expected)
 showError (FancyError offset fancy) =
   "Parse error at offset " ++ show offset ++ ":\n " ++ unlines (map show (Set.toList fancy))
 showError (TrivialError offset Nothing expected) =
   "Parse error at offset " ++ show offset ++ ": expected one of "
-    ++ show (Set.toList expected)
+  ++ show (Set.toList expected)

src/REPL.hs

@@ -1,25 +1,71 @@
 module REPL where
 
 import Eval
+import FileEval
 import Lexer
 import Parser
 import Research
 
-import Control.Monad         (void)
+import Control.Exception         (SomeException, catch)
-import qualified Data.Map as Map
+import Control.Monad.IO.Class    (liftIO)
-import System.IO            (hFlush, stdout)
+import Data.Char                 (isSpace)
+import Data.List                 (dropWhile, dropWhileEnd, intercalate)
+import System.Console.Haskeline
 
-repl :: Map.Map String T -> IO ()
+import qualified Data.Map as Map
-repl env = do
+
-  putStr "sapling > "
+repl :: Env -> IO ()
-  hFlush stdout
+repl env = runInputT defaultSettings (loop env)
-  input <- getLine
+  where
-  if input == "_:exit"
+    loop :: Env -> InputT IO ()
-    then putStrLn "Goodbye!"
+    loop env = do
-    else do
+      minput <- getInputLine "tricu < "
-      let clearEnv = Map.delete "__result" env
+      case minput of
-      let newEnv   = evalSingle clearEnv (parseSingle input)
+        Nothing -> outputStrLn "Exiting tricu"
+        Just s -> case strip s of 
+          "!exit" -> outputStrLn "Exiting tricu"
+          "!load" -> do
+            path <- getInputLine "File path to load < "
+            case path of
+              Nothing -> do
+                outputStrLn "No input received; stopping import."
+                loop env
+              Just path -> do
+                loadedEnv <- liftIO $ evaluateFileWithContext env (strip path)
+                loop $ Map.delete "__result" (Map.union loadedEnv env)
+          "" -> do
+            outputStrLn ""
+            loop env
+          input -> do
+            case (take 2 input) of 
+              "--" -> loop env
+              _ -> do
+                newEnv <- liftIO $ (processInput env input `catch` errorHandler env)
+                loop newEnv
+  
+    processInput :: Env -> String -> IO Env
+    processInput env input = do
+      let asts = parseTricu input
+          newEnv = evalTricu env asts
       case Map.lookup "__result" newEnv of
-        Just r  -> putStrLn $ "sapling < " ++ show r
+        Just r -> do
-        Nothing -> pure ()
+          putStrLn $ "tricu > " ++ decodeResult r
-      repl newEnv
+        Nothing -> return ()
+      return newEnv
+    
+    errorHandler :: Env -> SomeException -> IO (Env)
+    errorHandler env e = do
+      putStrLn $ "Error: " ++ show e
+      return env
+    
+    strip :: String -> String
+    strip = dropWhileEnd isSpace . dropWhile isSpace
+
+decodeResult :: T -> String
+decodeResult tc = case toNumber tc of
+  Right num -> show num
+  Left _ -> case toString tc of
+    Right str -> "\"" ++ str ++ "\""
+    Left _ -> case toList tc of
+      Right list -> "[" ++ intercalate ", " (map decodeResult list) ++ "]"
+      Left _ -> formatResult TreeCalculus tc

src/Research.hs

@@ -1,13 +1,57 @@
 module Research where
 
-import Data.List (intercalate)
 import Control.Monad.State
-import qualified Data.Map as Map
+import Data.List                 (intercalate)
-import Data.Map (Map)
+import Data.Map                  (Map)
+import Data.Text                 (Text, replace)
+import System.Console.CmdArgs    (Data, Typeable)
 
+import qualified Data.Map        as Map
+import qualified Data.Text as T
+
+-- Tree Calculus Types
 data T = Leaf | Stem T | Fork T T
   deriving (Show, Eq, Ord)
 
+-- Abstract Syntax Tree for tricu
+data TricuAST
+  = SVar String
+  | SInt Int
+  | SStr String
+  | SList [TricuAST]
+  | SFunc String [String] TricuAST
+  | SApp TricuAST TricuAST
+  | TLeaf
+  | TStem TricuAST
+  | TFork TricuAST TricuAST
+  | SLambda [String] TricuAST
+  | SEmpty
+  deriving (Show, Eq, Ord)
+
+-- Tokens from Lexer
+data LToken
+  = LKeywordT
+  | LIdentifier String
+  | LIntegerLiteral Int
+  | LStringLiteral String
+  | LAssign
+  | LColon
+  | LBackslash
+  | LOpenParen
+  | LCloseParen
+  | LOpenBracket
+  | LCloseBracket
+  | LNewline
+  deriving (Show, Eq, Ord)
+
+-- Output formats
+data EvaluatedForm = TreeCalculus | FSL | AST | Ternary | Ascii
+  deriving (Show, Data, Typeable)
+
+-- Environment containing previously evaluated TC terms
+type Env = Map.Map String T 
+
+-- Tree Calculus Reduction
 apply :: T -> T -> T
 apply Leaf b                            = Stem b
 apply (Stem a) b                        = Fork a b
@@ -17,16 +61,6 @@ apply (Fork (Fork a1 a2) a3) Leaf       = a1
 apply (Fork (Fork a1 a2) a3) (Stem u)   = apply a2 u
 apply (Fork (Fork a1 a2) a3) (Fork u v) = apply (apply a3 u) v
 
-reduce :: T -> T
-reduce expr =
-  let next = step expr
-  in if next == expr then expr else reduce next
-
-step :: T -> T
-step (Fork left right) = reduce (apply (reduce left) (reduce right))
-step (Stem inner) = Stem (reduce inner)
-step t = t
-
 -- SKI Combinators
 _S :: T
 _S = Fork (Stem (Fork Leaf Leaf)) Leaf
@@ -34,8 +68,11 @@ _S = Fork (Stem (Fork Leaf Leaf)) Leaf
 _K :: T
 _K = Stem Leaf
 
+-- Identity
+-- We use the "point-free" style which drops a redundant node
+-- Full I form (SKK): Fork (Stem (Stem Leaf)) (Stem Leaf)
 _I :: T
-_I = apply (apply _S _K) _K -- Fork (Stem (Stem Leaf)) (Stem Leaf)
+_I = Fork (Stem (Stem Leaf)) Leaf 
 
 -- Booleans
 _false :: T
@@ -48,35 +85,67 @@ _not :: T
 _not = Fork (Fork _true (Fork Leaf _false)) Leaf
 
 -- Marshalling
-toString :: String -> T
+ofString :: String -> T
-toString str = toList (map toNumber (map fromEnum str))
+ofString str = ofList (map ofNumber (map fromEnum str))
 
-ofString :: T -> String
+ofNumber :: Int -> T
-ofString tc = map (toEnum . ofNumber) (ofList tc)
+ofNumber 0 = Leaf
-
+ofNumber n =
-toNumber :: Int -> T
-toNumber 0 = Leaf
-toNumber n =
   Fork
     (if odd n then Stem Leaf else Leaf)
-    (toNumber (n `div` 2))
+    (ofNumber (n `div` 2))
 
-ofNumber :: T -> Int
+ofList :: [T] -> T
-ofNumber Leaf = 0
+ofList [] = Leaf
-ofNumber (Fork Leaf rest) = 2 * ofNumber rest
+ofList (x:xs) = Fork x (ofList xs)
-ofNumber (Fork (Stem Leaf) rest) = 1 + 2 * ofNumber rest
-ofNumber _ = error "Invalid Tree Calculus number"
 
-toList :: [T] -> T
+toNumber :: T -> Either String Int
-toList [] = Leaf
+toNumber Leaf = Right 0
-toList (x:xs) = Fork x (toList xs)
+toNumber (Fork Leaf rest) = case toNumber rest of
+  Right n -> Right (2 * n)
+  Left err -> Left err
+toNumber (Fork (Stem Leaf) rest) = case toNumber rest of
+  Right n -> Right (1 + 2 * n)
+  Left err -> Left err
+toNumber _ = Left "Invalid Tree Calculus number"
 
-ofList :: T -> [T]
+toString :: T -> Either String String
-ofList Leaf = []
+toString tc = case toList tc of
-ofList (Fork x rest) = x : ofList rest
+  Right list -> traverse (fmap toEnum . toNumber) list
-ofList _ = error "Invalid Tree Calculus list"
+  Left err -> Left "Invalid Tree Calculus string"
+
+toList :: T -> Either String [T]
+toList Leaf = Right []
+toList (Fork x rest) = case toList rest of
+  Right xs -> Right (x : xs)
+  Left err -> Left err
+toList _ = Left "Invalid Tree Calculus list"
+
+-- Outputs
+formatResult :: EvaluatedForm -> T -> String
+formatResult TreeCalculus = toSimpleT . show
+formatResult FSL          = show
+formatResult AST          = show . toAST
+formatResult Ternary      = toTernaryString
+formatResult Ascii        = toAscii
+
+toSimpleT :: String -> String
+toSimpleT s = T.unpack 
+  $ replace "Fork" "t"
+  $ replace "Stem" "t"
+  $ replace "Leaf" "t"
+  $ (T.pack s)
+
+toTernaryString :: T -> String
+toTernaryString Leaf = "0"
+toTernaryString (Stem t) = "1" ++ toTernaryString t
+toTernaryString (Fork t1 t2) = "2" ++ toTernaryString t1 ++ toTernaryString t2
+
+toAST :: T -> TricuAST
+toAST Leaf = TLeaf
+toAST (Stem a) = TStem (toAST a)
+toAST (Fork a b) = TFork (toAST a) (toAST b)
 
--- Utility
 toAscii :: T -> String
 toAscii tree = go tree "" True
   where
@@ -91,41 +160,4 @@ toAscii tree = go tree "" True
         ++ go left (prefix ++ (if isLast then "    " else "|   ")) False
         ++ go right (prefix ++ (if isLast then "    " else "|   ")) True
 
-rules :: IO ()
+-- Utility
-rules = putStr $ header
-              ++ (unlines $ tcRules)
-              ++ (unlines $ haskellRules)
-              ++ footer
-  where
-    tcRules :: [String]
-    tcRules =
-      [ "|                                                                               |"
-      , "|                  ┌--------- | Tree Calculus | ---------┐                      |"
-      , "|                  | 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    |                      |"
-      , "|                  └-------------------------------------┘                      |"
-      , "|                                                                               |"
-      ]
-    haskellRules :: [String]
-    haskellRules =
-      [ "| ┌------------------------------ | Haskell | --------------------------------┐ |"
-      , "| |                                                                           | |"
-      , "| | data T = Leaf | Stem T | Fork TT                                          | |"
-      , "| |                                                                           | |"
-      , "| | apply :: T -> T -> T                                                      | |"
-      , "| | apply Leaf b                            = Stem b                          | |"
-      , "| | apply (Stem a) b                        = Fork a b                        | |"
-      , "| | apply (Fork Leaf a) _                   = a                               | |"
-      , "| | apply (Fork (Stem a1) a2) b             = apply (apply a1 b) (apply a2 b) | |"
-      , "| | apply (Fork (Fork a1 a2) a3) Leaf       = a1                              | |"
-      , "| | apply (Fork (Fork a1 a2) a3) (Stem u)   = apply a2 u                      | |"
-      , "| | apply (Fork (Fork a1 a2) a3) (Fork u v) = apply (apply a3 u) v            | |"
-      , "| └---------------------------------------------------------------------------┘ |"
-      ]
-    header :: String
-    header = "┌-------------------- | Rules for evaluating Tree Calculus | -------------------┐\n"
-    footer :: String
-    footer = "└-------------------- | Rules for evaluating Tree Calculus | -------------------┘\n"

test/Spec.hs

@@ -1,241 +1,426 @@
 module Main where
 
 import Eval
+import FileEval
 import Lexer
 import Parser
+import REPL
 import Research
+
 import Control.Exception (evaluate, try, SomeException)
-import qualified Data.Map as Map
+import Control.Monad.IO.Class (liftIO)
 import Test.Tasty
 import Test.Tasty.HUnit
 import Test.Tasty.QuickCheck
 import Text.Megaparsec (runParser)
 
+import qualified Data.Map as Map
+import qualified Data.Set as Set
+
 main :: IO ()
 main = defaultMain tests
 
+runTricu :: String -> String
+runTricu s = show $ result (evalTricu Map.empty $ parseTricu s)
+
 tests :: TestTree
-tests = testGroup "Sapling Tests"
+tests = testGroup "Tricu Tests"
-    [ lexerTests
+  [ lexerTests
-    , parserTests
+  , parserTests
-    , integrationTests
+  , evaluationTests
-    , evaluationTests
+  , lambdaEvalTests
-    , propertyTests
+  , libraryTests
-    ]
+  , fileEvaluationTests
+  , propertyTests
+  ]
 
 lexerTests :: TestTree
 lexerTests = testGroup "Lexer Tests"
-    [ testCase "Lex simple identifiers" $ do
+  [ testCase "Lex simple identifiers" $ do
-        let input = "x a b = a"
+      let input = "x a b = a"
-            expect = Right [LIdentifier "x", LIdentifier "a", LIdentifier "b", LAssign, LIdentifier "a"]
+          expect = Right [LIdentifier "x", LIdentifier "a", LIdentifier "b", LAssign, LIdentifier "a"]
-        runParser saplingLexer "" input @?= expect
+      runParser tricuLexer "" input @?= expect
-    , testCase "Lex Tree Calculus terms" $ do
+  , testCase "Lex Tree Calculus terms" $ do
-        let input = "t t t"
+      let input = "t t t"
-            expect = Right [LKeywordT, LKeywordT, LKeywordT]
+          expect = Right [LKeywordT, LKeywordT, LKeywordT]
-        runParser saplingLexer "" input @?= expect
+      runParser tricuLexer "" input @?= expect
-    , testCase "Lex escaped characters in strings" $ do
+  , testCase "Lex escaped characters in strings" $ do
-        let input = "\"hello\\nworld\""
+      let input = "\"hello\\nworld\""
-            expect = Right [LStringLiteral "hello\\nworld"]
+          expect = Right [LStringLiteral "hello\\nworld"]
-        runParser saplingLexer "" input @?= expect
+      runParser tricuLexer "" input @?= expect
-    , testCase "Lex mixed literals" $ do
+  , testCase "Lex mixed literals" $ do
-        let input = "t \"string\" 42"
+      let input = "t \"string\" 42"
-            expect = Right [LKeywordT, LStringLiteral "string", LIntegerLiteral 42]
+          expect = Right [LKeywordT, LStringLiteral "string", LIntegerLiteral 42]
-        runParser saplingLexer "" input @?= expect
+      runParser tricuLexer "" input @?= expect
-    , testCase "Lex invalid token" $ do
+  , testCase "Lex invalid token" $ do
-        let input = "$invalid"
+      let input = "&invalid"
-        case runParser saplingLexer "" input of
+      case runParser tricuLexer "" input of
-            Left _ -> return ()
+        Left _ -> return ()
-            Right _ -> assertFailure "Expected lexer to fail on invalid token"
+        Right _ -> assertFailure "Expected lexer to fail on invalid token"
-    , testCase "Drop trailing whitespace in definitions" $ do
+  , testCase "Drop trailing whitespace in definitions" $ do
-        let input = "x = 5 "
+      let input = "x = 5 "
-            expect = [LIdentifier "x",LAssign,LIntegerLiteral 5]
+          expect = [LIdentifier "x",LAssign,LIntegerLiteral 5]
-        case (runParser saplingLexer "" input) of
+      case (runParser tricuLexer "" input) of
-            Left _ -> assertFailure "Failed to lex input"
+        Left _ -> assertFailure "Failed to lex input"
-            Right i -> i @?= expect
+        Right i -> i @?= expect
-    , testCase "Error when using invalid characters in identifiers" $ do
+  , testCase "Error when using invalid characters in identifiers" $ do
-        case (runParser saplingLexer "" "__result = 5") of
+        case (runParser tricuLexer "" "__result = 5") of
-            Left _ -> return ()
+          Left _ -> return ()
-            Right _ -> assertFailure "Expected failure when trying to assign the value of __result"
+          Right _ -> assertFailure "Expected failure when trying to assign the value of __result"
-    ]
+  ]
 
 parserTests :: TestTree
 parserTests = testGroup "Parser Tests"
-    [ testCase "Error when parsing incomplete definitions" $ do
+  [ testCase "Error when assigning a value to T" $ do
-        let input = lexSapling "x = "
+      let input = lexTricu "t = x"
-        case (runParser parseExpression "" input) of
+      case (runParser parseExpression "" input) of
-            Left _ -> return ()
+        Left _ -> return ()
-            Right _ -> assertFailure "Expected failure on invalid input"
+        Right _ -> assertFailure "Expected failure when trying to assign the value of T"
-    , testCase "Error when assigning a value to T" $ do
+  , testCase "Parse function definitions" $ do
-        let input = lexSapling "t = x"
+      let input = "x = (\\a b c : a)"
-        case (runParser parseExpression "" input) of
+          expect = SFunc "x" [] (SLambda ["a"] (SLambda ["b"] (SLambda ["c"] (SVar "a"))))
-            Left _ -> return ()
+      parseSingle input @?= expect
-            Right _ -> assertFailure "Expected failure when trying to assign the value of T"
+  , testCase "Parse nested Tree Calculus terms" $ do
-    , testCase "Error when parsing bodyless definitions with arguments" $ do
+      let input = "t (t t) t"
-        let input = lexSapling "x a b = "
+          expect = SApp (SApp TLeaf (SApp TLeaf TLeaf)) TLeaf
-        case (runParser parseExpression "" input) of
+      parseSingle input @?= expect
-            Left _ -> return ()
+  , testCase "Parse sequential Tree Calculus terms" $ do
-            Right _ -> assertFailure "Expected failure on invalid input"
+      let input = "t t t"
-    , testCase "Parse function definitions" $ do
+          expect = SApp (SApp TLeaf TLeaf) TLeaf
-        let input = "x a b c = a"
+      parseSingle input @?= expect
-        let expect = SFunc "x" ["a","b","c"] (SVar "a")
+  , testCase "Parse mixed list literals" $ do
-        parseSingle input @?= expect
+      let input = "[t (\"hello\") t]"
-    , testCase "Parse nested Tree Calculus terms" $ do
+          expect = SList [TLeaf, SStr "hello", TLeaf]
-        let input = "t (t t) t"
+      parseSingle input @?= expect
-        let expect = SApp (SApp TLeaf (SApp TLeaf TLeaf)) TLeaf
+  , testCase "Parse function with applications" $ do
-        parseSingle input @?= expect
+      let input  = "f = (\\x : t x)"
-    , testCase "Parse sequential Tree Calculus terms" $ do
+          expect = SFunc "f" [] (SLambda ["x"] (SApp TLeaf (SVar "x")))
-        let input = "t t t"
+      parseSingle input @?= expect
-        let expect = SApp (SApp TLeaf TLeaf) TLeaf
+  , testCase "Parse nested lists" $ do
-        parseSingle input @?= expect
+      let input  = "[t [(t t)]]"
-    , testCase "Parse mixed list literals" $ do
+          expect = SList [TLeaf,SList [SApp TLeaf TLeaf]]
-        let input = "[t (\"hello\") t]"
+      parseSingle input @?= expect
-        let expect = SList [TLeaf, SStr "hello", TLeaf]
+  , testCase "Parse complex parentheses" $ do
-        parseSingle input @?= expect
+      let input  = "t (t t (t t))"
-    , testCase "Parse function with applications" $ do
+          expect = SApp TLeaf (SApp (SApp TLeaf TLeaf) (SApp TLeaf TLeaf))
-        let input = "f x = t x"
+      parseSingle input @?= expect
-        let expect = SFunc "f" ["x"] (SApp TLeaf (SVar "x"))
+  , testCase "Parse empty list" $ do
-        parseSingle input @?= expect
+      let input  = "[]"
-     , testCase "Parse nested lists" $ do
+          expect = SList []
-        let input = "[t [(t t)]]"
+      parseSingle input @?= expect
-        let expect = SList [TLeaf,SList [SApp TLeaf TLeaf]]
+  , testCase "Parse multiple nested lists" $ do
-        parseSingle input @?= expect
+      let input  = "[[t t] [t (t t)]]"
-    , testCase "Parse complex parentheses" $ do
+          expect = SList [SList [TLeaf,TLeaf],SList [TLeaf,SApp TLeaf TLeaf]]
-        let input = "t (t t (t t))"
+      parseSingle input @?= expect
-        let expect = SApp TLeaf (SApp (SApp TLeaf TLeaf) (SApp TLeaf TLeaf))
+  , testCase "Parse whitespace variance" $ do
-        parseSingle input @?= expect
+      let input1 = "[t t]"
-    , testCase "Parse empty list" $ do
+      let input2 = "[ t t ]"
-        let input = "[]"
+          expect = SList [TLeaf, TLeaf]
-        let expect = SList []
+      parseSingle input1 @?= expect
-        parseSingle input @?= expect
+      parseSingle input2 @?= expect
-    , testCase "Parse multiple nested lists" $ do
+  , testCase "Parse string in list" $ do
-        let input = "[[t t] [t (t t)]]"
+      let input  = "[(\"hello\")]"
-        let expect = SList [SList [TLeaf,TLeaf],SList [TLeaf,SApp TLeaf TLeaf]]
+          expect = SList [SStr "hello"]
-        parseSingle input @?= expect
+      parseSingle input @?= expect
-    , testCase "Parse whitespace variance" $ do
+  , testCase "Parse parentheses inside list" $ do
-        let input1 = "[t t]"
+      let input  = "[t (t t)]"
-        let input2 = "[ t t ]"
+          expect = SList [TLeaf,SApp TLeaf TLeaf]
-        let expect = SList [TLeaf, TLeaf]
+      parseSingle input @?= expect
-        parseSingle input1 @?= expect
+  , testCase "Parse nested parentheses in function body" $ do
-        parseSingle input2 @?= expect
+      let input  = "f = (\\x : t (t (t t)))"
-    , testCase "Parse string in list" $ do
+          expect = SFunc "f" [] (SLambda ["x"] (SApp TLeaf (SApp TLeaf (SApp TLeaf TLeaf))))
-        let input = "[(\"hello\")]"
+      parseSingle input @?= expect
-        let expect = SList [SStr "hello"]
+  , testCase "Parse lambda abstractions" $ do
-        parseSingle input @?= expect
+      let input  = "(\\a : a)"
-    , testCase "Parse parentheses inside list" $ do
+          expect = (SLambda ["a"] (SVar "a"))
-        let input = "[t (t t)]"
+      parseSingle input @?= expect
-        let expect = SList [TLeaf,SApp TLeaf TLeaf]
+  , testCase "Parse multiple arguments to lambda abstractions" $ do
-        parseSingle input @?= expect
+      let input  = "x = (\\a b : a)"
-    , testCase "Parse nested parentheses in function body" $ do
+          expect = SFunc "x" [] (SLambda ["a"] (SLambda ["b"] (SVar "a")))
-        let input = "f = t (t (t t))"
+      parseSingle input @?= expect
-        let expect = SFunc "f" [] (SApp TLeaf (SApp TLeaf (SApp TLeaf TLeaf)))
+  , testCase "Grouping T terms with parentheses in function application" $ do
-        parseSingle input @?= expect
+      let input  = "x = (\\a : a)\nx (t)"
-    , testCase "Parse lambda abstractions" $ do
+          expect = [SFunc "x" [] (SLambda ["a"] (SVar "a")),SApp (SVar "x") TLeaf]
-        let input = "(\\a : a)"
+      parseTricu input @?= expect
-        let expect = (SLambda ["a"] (SVar "a"))
+  , testCase "Comments 1" $ do
-        parseSingle input @?= expect
+      let input = "(t) (t) -- (t)"
-    , testCase "Parse multiple arguments to lambda abstractions" $ do
+          expect = [SApp TLeaf TLeaf]
-        let input = "x = (\\a b : a)"
+      parseTricu input @?= expect
-        let expect = SFunc "x" [] (SLambda ["a"] (SLambda ["b"] (SVar "a")))
+  , testCase "Comments 2" $ do
-        parseSingle input @?= expect
+      let input = "(t) -- (t) -- (t)"
-     , testCase "Grouping T terms with parentheses in function application" $ do
+          expect = [TLeaf]
-        let input  = "x = (\\a : a)\n" <> "x (t)"
+      parseTricu input @?= expect
-            expect = [SFunc "x" [] (SLambda ["a"] (SVar "a")),SApp (SVar "x") TLeaf]
+  , testCase "Comments with no terms" $ do
-        parseSapling input @?= expect
+      let input = unlines ["-- (t)", "(t t)"]
-    ]
+          expect = [SEmpty,SApp TLeaf TLeaf]
-
+      parseTricu input @?= expect 
-integrationTests :: TestTree
+  ]
-integrationTests = testGroup "Integration Tests"
-    [ testCase "Combine lexer and parser" $ do
-        let input = "x = t t t"
-        let expect = SFunc "x" [] (SApp (SApp TLeaf TLeaf) TLeaf)
-        parseSingle input @?= expect
-    , testCase "Complex Tree Calculus expression" $ do
-        let input = "t (t t t) t"
-        let expect = SApp (SApp TLeaf (SApp (SApp TLeaf TLeaf) TLeaf)) TLeaf
-        parseSingle input @?= expect
-    ]
 
 evaluationTests :: TestTree
 evaluationTests = testGroup "Evaluation Tests"
-    [ testCase "Evaluate single Leaf" $ do
+  [ testCase "Evaluate single Leaf" $ do
-        let input = "t"
+      let input = "t"
-        let ast = parseSingle input
+      let ast = parseSingle input
-        (result $ evalSingle Map.empty ast) @?= Leaf
+      (result $ evalSingle Map.empty ast) @?= Leaf
-    , testCase "Evaluate single Stem" $ do
+  , testCase "Evaluate single Stem" $ do
-        let input = "t t"
+      let input = "t t"
-        let ast = parseSingle input
+      let ast = parseSingle input
-        (result $ evalSingle Map.empty ast) @?= Stem Leaf
+      (result $ evalSingle Map.empty ast) @?= Stem Leaf
-    , testCase "Evaluate single Fork" $ do
+  , testCase "Evaluate single Fork" $ do
-        let input = "t t t"
+      let input = "t t t"
-        let ast = parseSingle input
+      let ast = parseSingle input
-        (result $ evalSingle Map.empty ast) @?= Fork Leaf Leaf
+      (result $ evalSingle Map.empty ast) @?= Fork Leaf Leaf
-    , testCase "Evaluate nested Fork and Stem" $ do
+  , testCase "Evaluate nested Fork and Stem" $ do
-        let input = "t (t t) t"
+      let input = "t (t t) t"
-        let ast = parseSingle input
+      let ast = parseSingle input
-        (result $ evalSingle Map.empty ast) @?= Fork (Stem Leaf) Leaf
+      (result $ evalSingle Map.empty ast) @?= Fork (Stem Leaf) Leaf
-    , testCase "Evaluate `not` function" $ do
+  , testCase "Evaluate `not` function" $ do
-        let input = "t (t (t t) (t t t)) t"
+      let input = "t (t (t t) (t t t)) t"
-        let ast = parseSingle input
+      let ast = parseSingle input
-        (result $ evalSingle Map.empty ast) @?=
+      (result $ evalSingle Map.empty ast) @?=
-            Fork (Fork (Stem Leaf) (Fork Leaf Leaf)) Leaf
+        Fork (Fork (Stem Leaf) (Fork Leaf Leaf)) Leaf
-    , testCase "Environment updates with definitions" $ do
+  , testCase "Environment updates with definitions" $ do
-        let input = "x = t\ny = x"
+      let input = "x = t\ny = x"
-        let env = evalSapling Map.empty (parseSapling input)
+          env = evalTricu Map.empty (parseTricu input)
-        Map.lookup "x" env @?= Just Leaf
+      Map.lookup "x" env @?= Just Leaf
-        Map.lookup "y" env @?= Just Leaf
+      Map.lookup "y" env @?= Just Leaf
-    , testCase "Variable substitution" $ do
+  , testCase "Variable substitution" $ do
-        let input = "x = t t\ny = t x\ny"
+      let input = "x = t t\ny = t x\ny"
-        let env = evalSapling Map.empty (parseSapling input)
+          env = evalTricu Map.empty (parseTricu input)
-        (result env) @?= Stem (Stem Leaf)
+      (result env) @?= Stem (Stem Leaf)
-     , testCase "Multiline input evaluation" $ do
+  , testCase "Multiline input evaluation" $ do
-        let input = "x = t\ny = t t\nx"
+      let input = "x = t\ny = t t\nx"
-        let env = evalSapling Map.empty (parseSapling input)
+          env = evalTricu Map.empty (parseTricu input)
-        (result env) @?= Leaf
+      (result env) @?= Leaf
-     , testCase "Evaluate string literal" $ do
+  , testCase "Evaluate string literal" $ do
-        let input = "\"hello\""
+      let input = "\"hello\""
-        let ast = parseSingle input
+      let ast = parseSingle input
-        (result $ evalSingle Map.empty ast) @?= toString "hello"
+      (result $ evalSingle Map.empty ast) @?= ofString "hello"
-    , testCase "Evaluate list literal" $ do
+  , testCase "Evaluate list literal" $ do
-        let input = "[t (t t)]"
+      let input = "[t (t t)]"
-        let ast = parseSingle input
+      let ast = parseSingle input
-        (result $ evalSingle Map.empty ast) @?= toList [Leaf, Stem Leaf]
+      (result $ evalSingle Map.empty ast) @?= ofList [Leaf, Stem Leaf]
-    , testCase "Evaluate empty list" $ do
+  , testCase "Evaluate empty list" $ do
-        let input = "[]"
+      let input = "[]"
-        let ast = parseSingle input
+      let ast = parseSingle input
-        (result $ evalSingle Map.empty ast) @?= toList []
+      (result $ evalSingle Map.empty ast) @?= ofList []
-    , testCase "Evaluate variable dependency chain" $ do
+  , testCase "Evaluate variable dependency chain" $ do
-        let input = "x = t (t t)\n \
+      let input = "x = t (t t)\n \
-                    \ y = x\n \
+                  \ y = x\n \
-                    \ z = y\n \
+                  \ z = y\n \
-                    \ variablewithamuchlongername = z\n \
+                  \ variablewithamuchlongername = z\n \
-                    \ variablewithamuchlongername"
+                  \ variablewithamuchlongername"
-        let env = evalSapling Map.empty (parseSapling input)
+          env = evalTricu Map.empty (parseTricu input)
-        (result env) @?= (Stem (Stem Leaf))
+      (result env) @?= (Stem (Stem Leaf))
-    , testCase "Evaluate variable shadowing" $ do
+  , testCase "Evaluate variable shadowing" $ do
-        let input = "x = t t\nx = t\nx"
+      let input = "x = t t\nx = t\nx"
-        let env = evalSapling Map.empty (parseSapling input)
+          env = evalTricu Map.empty (parseTricu input)
-        (result env) @?= Leaf
+      (result env) @?= Leaf
-    , testCase "Lambda identity" $ do
+  , testCase "Apply identity to Boolean Not" $ do
-        let input = "(\\a : a)"
+      let not = "(t (t (t t) (t t t)) t)"
-            env = evalSapling Map.empty (parseSapling input)
+      let input = "x = (\\a : a)\nx " ++ not
-        result env @?= Fork (Stem (Stem Leaf)) (Stem Leaf)
+          env = evalTricu Map.empty (parseTricu input)
-    , testCase "Apply identity to Boolean Not" $ do
+      result env @?= Fork (Fork (Stem Leaf) (Fork Leaf Leaf)) Leaf
-        let not = "(t (t (t t) (t t t)) t)"
+  ]
-            input = "x = (\\a : a)\nx " ++ not
+
-            env = evalSapling Map.empty (parseSapling input)
+lambdaEvalTests :: TestTree
-        result env @?= Fork (Fork (Stem Leaf) (Fork Leaf Leaf)) Leaf
+lambdaEvalTests = testGroup "Lambda Evaluation Tests"
-    , testCase "Constant function matches" $ do
+  [ testCase "Lambda Identity Function" $ do
-        let input = "k = (\\a b : a)\nk (t t) t"
+      let input = "id = (\\x : x)\nid t"
-            env = evalSapling Map.empty (parseSapling input)
+      runTricu input @?= "Leaf"
-        result env @?= Stem Leaf
+  , testCase "Lambda Constant Function (K combinator)" $ do
-    ]
+      let input = "k = (\\x y : x)\nk t (t t)"
+      runTricu input @?= "Leaf"
+  , testCase "Lambda Application with Variable" $ do
+      let input = "id = (\\x : x)\nval = t t\nid val"
+      runTricu input @?= "Stem Leaf"
+  , testCase "Lambda Application with Multiple Arguments" $ do
+      let input = "apply = (\\f x y : f x y)\nk = (\\a b : a)\napply k t (t t)"
+      runTricu input @?= "Leaf"
+   , testCase "Nested Lambda Application" $ do
+      let input = "apply = (\\f x y : f x y)\nid = (\\x : x)\napply (\\f x : f x) id t"
+      runTricu input @?= "Leaf"
+  , testCase "Lambda with a complex body" $ do
+      let input = "f = (\\x : t (t x))\nf t"
+      runTricu input @?= "Stem (Stem Leaf)"
+  , testCase "Lambda returning a function" $ do
+      let input = "f = (\\x : (\\y : x))\ng = f t\ng (t t)"
+      runTricu input @?= "Leaf"
+  , testCase "Lambda with Shadowing" $ do
+      let input = "f = (\\x : (\\x : x))\nf t (t t)"
+      runTricu input @?= "Stem Leaf"
+   , testCase "Lambda returning another lambda" $ do
+      let input = "k = (\\x : (\\y : x))\nk_app = k t\nk_app (t t)"
+      runTricu input @?= "Leaf"
+   , testCase "Lambda with free variables" $ do
+      let input = "y = t t\nf = (\\x : y)\nf t"
+      runTricu input @?= "Stem Leaf"
+   , testCase "SKI Composition" $ do
+      let input = "s = (\\x y z : x z (y z))\nk = (\\x y : x)\ni = (\\x : x)\ncomp = s k i\ncomp t (t t)"
+      runTricu input @?= "Stem (Stem Leaf)"
+   , testCase "Lambda with multiple parameters and application" $ do
+      let input = "f = (\\a b c : t a b c)\nf t (t t) (t t t)"
+      runTricu input @?= "Stem Leaf"
+   , testCase "Lambda with nested application in the body" $ do
+      let input = "f = (\\x : t (t (t x)))\nf t"
+      runTricu input @?= "Stem (Stem (Stem Leaf))"
+    , testCase "Lambda returning a function and applying it" $ do
+        let input = "f = (\\x : (\\y : t x y))\ng = f t\ng (t t)"
+        runTricu input @?= "Fork Leaf (Stem Leaf)"
+    , testCase "Lambda applying a variable" $ do
+        let input = "id = (\\x : x)\na = t t\nid a"
+        runTricu input @?= "Stem Leaf"
+    , testCase "Nested lambda abstractions in the same expression" $ do
+        let input = "f = (\\x : (\\y : x y))\ng = (\\z : z)\nf g t"
+        runTricu input @?= "Leaf"
+  , testCase "Lambda with a 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
+        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
+        let input = "f = (\\x : x)\nf [t (t t)]"
+        runTricu input @?= "Fork Leaf (Fork (Stem Leaf) Leaf)"
+  ]
+
+libraryTests :: TestTree
+libraryTests = 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"
+      let input = "test t"
+          env = decodeResult $ result $ evalTricu library (parseTricu input)
+      env @?= "\"Leaf\""
+  , testCase "Triage test (Stem Leaf)" $ do
+      library <- evaluateFile "./lib/base.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"
+      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"
+      let input = "not true"
+          env = result $ evalTricu library (parseTricu input)
+      env @?= Leaf
+  , testCase "Boolean NOT: false" $ do
+      library <- evaluateFile "./lib/base.tri"
+      let input = "not false"
+          env = result $ evalTricu library (parseTricu input)
+      env @?= Stem Leaf
+  , testCase "Boolean AND TF" $ do
+      library <- evaluateFile "./lib/base.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"
+      let input = "and (t) (t t)"
+          env = evalTricu library (parseTricu input)
+      result env @?= Leaf
+  , testCase "Boolean AND FF" $ do
+      library <- evaluateFile "./lib/base.tri"
+      let input = "and (t) (t)"
+          env = evalTricu library (parseTricu input)
+      result env @?= Leaf
+  , testCase "Boolean AND TT" $ do
+      library <- evaluateFile "./lib/base.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"
+      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"
+      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"
+      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"
+      let input = "emptyList []"
+          env = evalTricu library (parseTricu input)
+      result env @?= Stem Leaf
+  , testCase "Non-empty list check" $ do
+      library <- evaluateFile "./lib/base.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"
+      let input = "lconcat \"Hello, \" \"world!\""
+          env = decodeResult $ result $ evalTricu library (parseTricu input)
+      env @?= "\"Hello, world!\""
+  , testCase "Verifying Equality" $ do
+      library <- evaluateFile "./lib/base.tri"
+      let input = "equal (t t t) (t t t)"
+          env = evalTricu library (parseTricu input)
+      result env @?= Stem Leaf
+  ]
+
+fileEvaluationTests :: TestTree
+fileEvaluationTests = testGroup "Evaluation tests"
+  [ testCase "Forks" $ do
+      res <- liftIO $ evaluateFileResult "./test/fork.tri"
+      res @?= Fork Leaf Leaf
+  , testCase "File ends with comment" $ do
+      res <- liftIO $ evaluateFileResult "./test/comments-1.tri"
+      res @?= Fork (Stem Leaf) Leaf
+  , testCase "Mapping and Equality" $ do
+      res <- liftIO $ evaluateFileResult "./test/map.tri"
+      res @?= Stem Leaf
+  , testCase "Eval and decoding string" $ do
+      library <- liftIO $ evaluateFile "./lib/base.tri"
+      res <- liftIO $ evaluateFileWithContext library "./test/string.tri"
+      decodeResult (result res) @?= "\"String test!\""
+  ]
 
 propertyTests :: TestTree
 propertyTests = testGroup "Property Tests"
-    [ testProperty "Lexing and parsing round-trip" $ \input ->
+  [ testProperty "Lexing and parsing round-trip" $ \input ->
-        case runParser saplingLexer "" input of
+      case runParser tricuLexer "" input of
-            Left _ -> property True
+        Left _ -> property True
-            Right tokens -> case runParser parseExpression "" tokens of
+        Right tokens -> case runParser parseExpression "" tokens of
-                Left _ -> property True
+          Left _ -> property True
-                Right ast -> parseSingle input === ast
+          Right ast -> parseSingle input === ast
-    ]
+  ]

test/ascii.tri

@@ -0,0 +1 @@
+t (t (t (t (t t) (t t t)) t) t t) t

test/assignment.tri

@@ -0,0 +1 @@
+x = t (t t) t

test/comments-1.tri

@@ -0,0 +1,9 @@
+-- This is a tricu comment!
+-- t (t t) (t (t t t))
+-- t (t t t) (t t)
+-- x = (\a : a)
+t (t t) t -- Fork (Stem Leaf) Leaf
+-- t t
+-- x
+-- x = (\a : a)
+-- t

test/fork.tri

@@ -0,0 +1 @@
+t t t 

test/map.tri

@@ -0,0 +1,24 @@
+false = t
+true = t 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)
+iC = (\a b c : s a (k c) b)
+yi = (\i : b m (c b (i m)))
+y = yi iC
+triage = (\a b c : t (t a b) c)
+pair = t
+matchList = (\oe oc : triage oe _ oc)
+lconcat = y (\self : matchList (\k : k) (\h r k : pair h (self r k)))
+hmap = y (\self : matchList (\f : t) (\hd tl f : pair (f hd) (self tl f)))
+map = (\f l : hmap l f)
+lAnd = triage (\x : false) (\_ x : x) (\_ _ x : x)
+lOr = triage (\x : x) (\_ _ : true) (\_ _ x : true)
+equal = y (\self : triage (triage true (\z : false) (\y z : false)) (\ax : triage false (self ax) (\y z : false)) (\ax ay : triage false (\z : false) (\bx by : lAnd (self ax bx) (self ay by))))
+
+x = map (\i : lconcat "Successfully concatenated " i) [("two strings!")]
+equal x [("Successfully concatenated two strings!")]

test/string.tri

@@ -0,0 +1 @@
+head (map (\i : lconcat "String " i) [("test!")])

tricu.cabal

@@ -1,8 +1,8 @@
 cabal-version: 1.12
 
-name:           sapling
+name:           tricu
-version:        0.2.0
+version:        0.5.0
-description:    Tree Calculus experiment repository
+description:    A micro-language for exploring Tree Calculus
 author:         James Eversole
 maintainer:     james@eversole.co
 copyright:      James Eversole
@@ -12,48 +12,53 @@ build-type:     Simple
 extra-source-files:
     README.md
 
-executable sapling
+executable tricu
   main-is: Main.hs
   hs-source-dirs:
       src
   default-extensions:
-      ConstraintKinds
+      DeriveDataTypeable
-      DataKinds
-      DeriveGeneric
-      FlexibleContexts
-      FlexibleInstances
-      GeneralizedNewtypeDeriving
       OverloadedStrings
-      ScopedTypeVariables
   ghc-options: -threaded -rtsopts -with-rtsopts=-N -optl-pthread -fPIC
   build-depends:
     base >=4.7
+    , cmdargs
     , containers
+    , haskeline
     , megaparsec
     , mtl
+    , text
   other-modules:
     Eval
+    FileEval
     Lexer
     Parser
     REPL
     Research
   default-language: Haskell2010
 
-test-suite sapling-tests
+test-suite tricu-tests
   type:                exitcode-stdio-1.0
   main-is:             Spec.hs
   hs-source-dirs:      test, src
+  default-extensions:
+      DeriveDataTypeable
+      OverloadedStrings
   build-depends:       
     base
+    , cmdargs
     , containers
+    , haskeline
     , megaparsec
     , mtl
     , tasty
     , tasty-hunit
     , tasty-quickcheck
+    , text
   default-language:    Haskell2010
   other-modules:
     Eval
+    FileEval
     Lexer
     Parser
     REPL