Remove Nix caching that can't work due to /nix/store permissions

Adds support for several special characters in identifiers. Adds a demo
for converting values to source code and another for checking equality.
Updates the existing demo and tests to reflect new names for functions
returning booleans.

.gitea/workflows/test-and-build.yml

@@ -0,0 +1,69 @@
+name: Test, Build, and Release
+
+on: 
+  push:
+    tags:
+      - '*'
+
+jobs:
+  test:
+    container:
+      image: docker.matri.cx/nix-runner:v0.1.0
+      credentials:
+        username: ${{ secrets.REGISTRY_USERNAME }}
+        password: ${{ secrets.REGISTRY_PASSWORD }}
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+
+      - name: Set up cache for Cabal
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cache/cabal
+            ~/.config/cabal
+            ~/.local/state/cabal
+          key: cabal-${{ hashFiles('tricu.cabal') }}
+          restore-keys: |
+            cabal-
+
+      - name: Initialize Cabal and update package list
+        run: |
+          nix develop --command cabal update
+
+      - name: Run test suite
+        run: |
+          nix develop --command cabal test
+
+  build:
+    needs: test
+    container:
+      image: docker.matri.cx/nix-runner:v0.1.0
+      credentials:
+        username: ${{ secrets.REGISTRY_USERNAME }}
+        password: ${{ secrets.REGISTRY_PASSWORD }}
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+
+      - name: Build and shrink binary
+        run: |
+          nix build
+          cp -L ./result/bin/tricu ./tricu
+          chmod 755 ./tricu
+          nix develop --command upx ./tricu
+  
+      - name: Setup go for release action
+        uses: actions/setup-go@v5
+        with:
+          go-version: '>=1.20.1'
+  
+      - name: Release binary
+        uses: https://gitea.com/actions/release-action@main
+        with:
+          files: |-
+            ./tricu
+          api_key: '${{ secrets.RELEASE_TOKEN }}'
+          pre_release: true

.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

@@ -1,54 +1,82 @@
-# sapling
+# tricu
 
 ## Introduction
 
-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) .
+tricu (pronounced "tree-shoe") 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).
 
-It offers a minimal amount of syntax sugar:
+tricu offers minimal syntax sugar yet manages to provide a complete, intuitive, and familiar programming environment. There is great power in simplicity. tricu offers:
 
-- `t` operator behaving by the rules of Tree Calculus
-- Function ("variable") definitions
-- Lambda abstractions
-- List, Number, and String literals (WIP)
+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
 
-This is an active experimentation project by [someone who has no idea what they're doing](https://eversole.co).
+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.
 
-## What does it look like?
+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.
+
+## REPL examples
 
 ```
-false      = t
-_          = t
-true       = t t
-id         = (\a : a)
-triage     = (\a b c : t (t a b) c) 
-match_bool = (\ot of : triage of (\_ : ot) t)
-and        = match_bool id (\_ : false)
-if         = (\cond then else : t (t else (t t then)) t cond)
-triage     = (\a b c : t (t a b) c)
-test       = triage "leaf" (\_ : "stem") (\_ _ : "fork")
+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!"
 
--- The REPL outputs the tree form results by default; they are elided here.
-sapling < test t
-DECODE -: "leaf"
-sapling < test (t t)
-DECODE -: "stem"
-sapling < test (t t t)
-DECODE -: "fork"
-sapling < map (\i : listConcat i " is super cool!") [("He") ("She") ("Everybody")]
-DECODE -: ["He is super cool!", "She is super cool!", "Everybody is super cool!"]
+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 convert a term back to source code (/demos/toSource.tri)
+tricu < toSource not?
+tricu > "(t (t (t t) (t t t)) (t t (t t t)))"
 ```
 
-## How to use
+## Installation and Use
 
-For now, you can easily build and run this project using Nix:
+You can easily build and/or run this project using [Nix](https://nixos.org/download/).
 
-1. Clone the repository:
-    a. `git clone ssh://git.eversole.co/sapling.git`
-    b. `git clone https://git.eversole/sapling.git`
-1. Run the REPL: `nix run`
+- 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 Tree Calculus code playground created by [Johannes Bader](https://johannes-bader.com/) that introduced me to Tree Calculus.

demos/equality.tri

@@ -0,0 +1,24 @@
+false = t
+true  = t t
+
+triage = (\a b c : t (t a b) c)
+
+matchBool = (\ot of : triage
+  of
+  (\_ : ot)
+  (\_ _ : ot)
+)
+
+not_TC?     = t (t (t t) (t t t)) (t t (t t t))
+not_Lambda? = matchBool false true
+
+areEqual? = equal not_TC not_Lambda
+
+true_TC?  = not_TC false
+false_TC? = not_TC true
+
+true_Lambda?  = not_Lambda false
+false_Lambda? = not_Lambda true
+
+areTrueEqual?  = equal true_TC  true_Lambda
+areFalseEqual? = equal false_TC false_Lambda

demos/levelOrderTraversal.tri

@@ -0,0 +1,65 @@
+-- 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
+--
+
+label = (\node : head node)
+
+left  = (\node : if (emptyList node) 
+  [] 
+  (if (emptyList (tail node)) 
+    [] 
+    (head (tail node))))
+
+right = (\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 label queue) (self (filter 
+    (\node : not (emptyList node)) 
+      (lconcat (map left queue) (map right 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) ""
+
+levelOrderTraversal = (\s : lconcat (t 10 t) (flatten (levelOrderToString s)))
+
+exampleOne = levelOrderTraversal [("1") 
+                                 [("2") [("4") t t] t] 
+                                 [("3") [("5") t t] [("6") t t]]]
+
+exampleTwo = levelOrderTraversal [("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]]]
+
+exampleTwo

demos/toSource.tri

@@ -0,0 +1,46 @@
+-- Thanks to intensionality, we can inspect the structure of a given value
+-- even if it's a function. This includes lambdas which are eliminated to
+-- Tree Calculus (TC) terms during evaluation.
+
+-- Triage takes four arguments: the first three represent behaviors for each 
+-- structural case in Tree Calculus (Leaf, Stem, and Fork).
+-- The fourth argument is the value whose structure is inspected. By evaluating 
+-- the Tree Calculus term, `triage` enables branching logic based on the term's 
+-- shape, making it possible to perform structure-specific operations such as
+-- reconstructing the terms' source code representation.
+triage = (\a b c : t (t a b) c)
+
+-- Base case of a single Leaf
+sourceLeaf = t (head "t")
+
+-- Stem case
+sourceStem = (\convert : (\a rest :
+  t (head "(")                       -- Start with a left parenthesis "(".
+    (t (head "t")                    -- Add a "t"
+      (t (head " ")                  -- Add a space.
+        (convert a                   -- Recursively convert the argument.
+          (t (head ")") rest))))))   -- Close with ")" and append the rest.
+
+-- Fork case
+sourceFork = (\convert : (\a b rest :
+  t (head "(")                           -- Start with a left parenthesis "(".
+    (t (head "t")                        -- Add a "t"
+      (t (head " ")                      -- Add a space.
+        (convert a                       -- Recursively convert the first arg.
+          (t (head " ")                  -- Add another space.
+            (convert b                   -- Recursively convert the second arg.
+              (t (head ")") rest)))))))) -- Close with ")" and append the rest.
+
+-- Wrapper around triage 
+toSource_ = y (\self arg :
+  triage
+    sourceLeaf        -- Triage `a` case, Leaf
+    (sourceStem self) -- Triage `b` case, Stem
+    (sourceFork self) -- Triage `c` case, Fork
+    arg)              -- The term to be inspected
+
+-- toSource takes a single TC term and returns a String
+toSource = (\v : toSource_ v "")
+
+exampleOne = toSource true -- OUT: "(t t)"
+exampleTwo = toSource not  -- OUT: "(t (t (t t) (t t t)) (t t (t 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.${packageName} =
@@ -32,10 +32,11 @@
         defaultPackage = self.packages.${system}.default;
 
         devShells.default = pkgs.mkShell {
-          buildInputs = with pkgs.haskellPackages; [
-            cabal-install
-            ghcid
+          buildInputs = with pkgs; [
+            haskellPackages.cabal-install
+            haskellPackages.ghcid
             customGHC
+            upx
           ];
           inputsFrom = builtins.attrValues self.packages.${system};
         };

lib/base.tri

@@ -0,0 +1,96 @@
+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)
+pair  = t
+if    = (\cond then else : t (t else (t t then)) t cond)
+
+triage = (\a b c : t (t a b) c)
+test   = triage "Leaf" (\_ : "Stem") (\_ _ : "Fork")
+
+matchBool = (\ot of : triage 
+  of 
+  (\_ : ot) 
+  (\_ _ : ot)
+)
+
+matchList = (\oe oc : triage 
+  oe 
+  _ 
+  oc
+)
+
+matchPair = (\op : triage 
+  _ 
+  _ 
+  op
+)
+
+not? = matchBool false true
+and? = matchBool id (\_ : false)
+emptyList? = matchList true (\_ _ : false)
+
+head = matchList t (\head _ : head)
+tail = matchList t (\_ tail : tail)
+
+lconcat = y (\self : matchList 
+  (\k : k) 
+  (\h r k : pair h (self r k)))
+
+lAnd = (triage 
+  (\_     : false) 
+  (\_ x   : x) 
+  (\_ _ x : x)
+)
+
+lOr = (triage 
+  (\x     : x) 
+  (\_ _   : true) 
+  (\_ _ _ : true)
+)
+
+map_ = y (\self : 
+  matchList 
+    (\_ : t) 
+    (\head tail f : pair (f head) (self tail f)))
+map = (\f l : map_ l f)
+
+equal? = y (\self : triage 
+  (triage 
+    true 
+    (\_   : false) 
+    (\_ _ : false)) 
+  (\ax : 
+    triage 
+      false 
+      (self ax) 
+      (\_ _ : false)) 
+  (\ax ay : 
+    triage 
+      false 
+      (\_ : false) 
+      (\bx by : lAnd (self ax bx) (self ay by))))
+
+filter_ = y (\self : matchList 
+  (\_ : t) 
+  (\head tail f : matchBool (t head) i (f head) (self tail f)))
+filter  = (\f l : filter_ l f)
+
+foldl_ = y (\self f l x : matchList (\acc : acc) (\head tail acc : self f tail (f acc head)) l x)
+foldl  = (\f x l : foldl_ f l x)
+
+foldr_ = y (\self x f l : matchList x (\head tail : f (self x f tail) head) l)
+foldr  = (\f x l : foldr_ x f l)

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

@@ -3,118 +3,90 @@ module Eval where
 import Parser
 import Research
 
-import Data.Map (Map)
+import Data.Map  (Map)
+
 import qualified Data.Map as Map
-import Data.List (foldl')
 import qualified Data.Set as Set
 
-evalSingle :: Map String T -> SaplingAST -> Map String T
-evalSingle env term = case term of
-  SFunc name [] body ->
-    let lineNoLambda = eliminateLambda body
-        result = evalAST env lineNoLambda
-    in Map.insert name result env
-  SLambda _ body ->
-    let result = evalAST env body
-    in Map.insert "__result" result env
-  SApp func arg ->
-    let result = apply (evalAST env $ eliminateLambda func) (evalAST env $ eliminateLambda arg)
-    in Map.insert "__result" result env
-  SVar name ->
-    case Map.lookup name env of
-      Just value -> Map.insert "__result" value env
-      Nothing -> error $ "Variable " ++ name ++ " not defined"
-  _ ->
-    let result = evalAST env term
-    in Map.insert "__result" result env
+evalSingle :: Env -> TricuAST -> Env
+evalSingle env term
+  | SFunc name [] body <- term =
+      let res = evalAST env body
+      in Map.insert "__result" res (Map.insert name res env)
+  | SApp func arg <- term =
+      let res = apply (evalAST env func) (evalAST env arg)
+      in Map.insert "__result" res env
+  | SVar name <- term =
+      case Map.lookup name env of
+        Just v  -> Map.insert "__result" v env
+        Nothing -> errorWithoutStackTrace $ "Variable " ++ name ++ " not defined"
+  | otherwise =
+      Map.insert "__result" (evalAST env term) env
 
-evalSapling :: Map String T -> [SaplingAST] -> Map String T
-evalSapling env [] = env
-evalSapling env [lastLine] =
-    let lastLineNoLambda = eliminateLambda lastLine
-        updatedEnv = evalSingle env lastLineNoLambda
-    in Map.insert "__result" (result updatedEnv) updatedEnv
-evalSapling env (line:rest) =
-    let lineNoLambda = eliminateLambda line
-        updatedEnv = evalSingle env lineNoLambda
-    in evalSapling updatedEnv rest
+evalTricu :: Env -> [TricuAST] -> Env
+evalTricu env []     = env
+evalTricu env [x]    =
+  let updatedEnv = evalSingle env x
+  in Map.insert "__result" (result updatedEnv) updatedEnv
+evalTricu env (x:xs) =
+  evalTricu (evalSingle env x) xs
 
-evalAST :: Map String T -> SaplingAST -> T
-evalAST env term = case term of
-    SVar name -> case Map.lookup name env of
-        Just value -> value
-        Nothing -> error $ "Variable " ++ name ++ " not defined"
-    TLeaf -> Leaf
-    TStem t -> Stem (evalAST env t)
-    TFork t1 t2 -> Fork (evalAST env t1) (evalAST env t2)
-    SApp t1 t2 -> apply (evalAST env t1) (evalAST env t2)
-    SStr str -> ofString str
-    SInt num -> ofNumber num
-    SList elems -> ofList (map (evalAST Map.empty) elems)
-    SFunc name args body ->
-        error $ "Unexpected function definition " ++ name
-        ++ " in evalAST; define via evalSingle."
-    SLambda {} -> error "Internal error: SLambda found in evalAST after elimination."
+evalAST :: Env -> TricuAST -> T
+evalAST env term
+  | SLambda _ _ <- term = evalAST env (elimLambda term)
+  | SVar   name <- term = evalVar name
+  | TLeaf       <- term = Leaf
+  | TStem  t    <- term = Stem (evalAST env t)
+  | TFork  t u  <- term = Fork (evalAST env t) (evalAST env u)
+  | SApp   t u  <- term = apply (evalAST env t) (evalAST env u)
+  | SStr   s    <- term = ofString s
+  | SInt   n    <- term = ofNumber n
+  | SList  xs   <- term = ofList (map (evalAST env) xs)
+  | SEmpty      <- term = Leaf
+  | otherwise           = errorWithoutStackTrace "Unexpected AST term"
+    where
+      evalVar name = Map.findWithDefault
+        (errorWithoutStackTrace $ "Variable " ++ name ++ " not defined")
+        name env
 
-eliminateLambda :: SaplingAST -> SaplingAST
-eliminateLambda (SLambda (v:vs) body)
-  | null vs = lambdaToT v (eliminateLambda body)
-  | otherwise = eliminateLambda (SLambda [v] (SLambda vs body))
-eliminateLambda (SApp f arg) = SApp (eliminateLambda f) (eliminateLambda arg)
-eliminateLambda (TStem t) = TStem (eliminateLambda t)
-eliminateLambda (TFork l r) = TFork (eliminateLambda l) (eliminateLambda r)
-eliminateLambda (SList xs) = SList (map eliminateLambda xs)
-eliminateLambda other = other
-
--- This is my attempt to implement the lambda calculus elimination rules defined
--- in "Typed Program Analysis without Encodings" by Barry Jay.
 -- https://github.com/barry-jay-personal/typed_tree_calculus/blob/main/typed_program_analysis.pdf
-lambdaToT :: String -> SaplingAST -> SaplingAST
-lambdaToT x (SVar y)
-  | x == y = tI
-lambdaToT x (SVar y)
-  | x /= y = SApp tK (SVar y)
-lambdaToT x t
-  | not (isFree x t) = SApp tK t
-lambdaToT x (SApp n u)
-  | not (isFree x (SApp n 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 body
-  | not (isFree x body) = SApp tK body
-  | otherwise = SApp (SApp tS (lambdaToT x body)) TLeaf
+-- Chapter 4: Lambda-Abstraction
+elimLambda :: TricuAST -> TricuAST
+elimLambda = go
+  where
+    go (SLambda (v:vs) body)
+      | null vs              = toSKI v (elimLambda body)
+      | otherwise            = elimLambda (SLambda [v] (SLambda vs body))
+    go (SApp f g)            = SApp (elimLambda f) (elimLambda g)
+    go x                     = x
 
-freeVars :: SaplingAST -> Set.Set String
-freeVars (SVar v) = Set.singleton v
-freeVars (SInt _) = Set.empty
-freeVars (SStr _) = Set.empty
-freeVars (SList xs) = foldMap freeVars xs
-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
+    toSKI x (SVar y)
+      | x == y           = _I
+      | otherwise        = SApp _K (SVar y)
+    toSKI x t@(SApp n u)
+      | not (isFree x t) = SApp _K t
+      | otherwise        = SApp (SApp _S (toSKI x n)) (toSKI x u)
+    toSKI x t
+      | not (isFree x t) = SApp _K t
+      | otherwise        = SApp (SApp _S (toSKI x t)) TLeaf
 
-isFree :: String -> SaplingAST -> Bool
-isFree x = Set.member x . freeVars
+    _S = parseSingle "t (t (t t t)) t"
+    _K = parseSingle "t t"
+    _I = parseSingle "t (t (t t)) t"
     
-toAST :: T -> SaplingAST
-toAST Leaf = TLeaf
-toAST (Stem a) = TStem (toAST a)
-toAST (Fork a b) = TFork (toAST a) (toAST b)
+    isFree x = Set.member x . freeVars
+    freeVars (SVar    v    ) = Set.singleton v
+    freeVars (SInt    _    ) = Set.empty
+    freeVars (SStr    _    ) = Set.empty
+    freeVars (SList   s    ) = foldMap freeVars s
+    freeVars (SApp    f a  ) = freeVars f <> freeVars a
+    freeVars (TLeaf        ) = Set.empty
+    freeVars (SFunc   _ _ b) = freeVars b
+    freeVars (TStem   t    ) = freeVars t
+    freeVars (TFork   l r  ) = freeVars l <> freeVars r
+    freeVars (SLambda v b  ) = foldr Set.delete (freeVars b) v
 
--- We need the SKI operators in an unevaluated SaplingAST tree form so that we
--- can keep the evaluation functions straightforward
-tI :: SaplingAST
-tI = SApp (SApp TLeaf (SApp TLeaf (SApp TLeaf TLeaf))) TLeaf
-
-tK :: SaplingAST
-tK = SApp TLeaf TLeaf
-
-tS :: SaplingAST
-tS = SApp (SApp TLeaf (SApp TLeaf (SApp (SApp TLeaf TLeaf) TLeaf))) TLeaf
-
-result :: Map String T -> T
+result :: Env -> T
 result r = case Map.lookup "__result" r of
-    Just a -> a
-    Nothing -> error "No __result field found in provided environment"
+  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

@@ -1,37 +1,28 @@
 module Lexer where
 
 import Research
-import Text.Megaparsec
-import Text.Megaparsec.Char
 
-import Control.Monad (void)
+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
-  | LComment String
-  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 
+              <|> digitChar 
+              <|> char '_' <|> char '-' <|> char '?' <|> char '!'
+              <|> char '$' <|> char '#' <|> char '@' <|> char '%'
+  let name = first : rest
   if (name == "t" || name == "__result")
     then fail "Keywords (`t`, `__result`) cannot be used as an identifier"
     else return (LIdentifier name)
@@ -45,11 +36,8 @@ stringLiteral :: Lexer LToken
 stringLiteral = do
   char '"'
   content <- many (noneOf ['"'])
-  if null content
-    then fail "Empty string literals are not allowed"
-    else do
-      char '"' --"
-      return (LStringLiteral content)
+  char '"' --"
+  return (LStringLiteral content)
 
 assign :: Lexer LToken
 assign = char '=' *> pure LAssign
@@ -75,34 +63,39 @@ closeBracket = char ']' *> pure LCloseBracket
 lnewline :: Lexer LToken
 lnewline = char '\n' *> pure LNewline
 
-comment :: Lexer LToken
-comment = do
-  string "--"
-  content <- many (satisfy (/= '\n'))
-  optional (char '\n')
-  pure (LComment content)
-
-
 sc :: Lexer ()
-sc = skipMany (void (char ' ') <|> void (char '\t') <|> void comment)
+sc = space
+  (void $ takeWhile1P (Just "space") (\c -> c == ' ' || c == '\t'))
+  (skipLineComment "--")
+  (skipBlockComment "|-" "-|")
 
-saplingLexer :: Lexer [LToken]
-saplingLexer = many (sc *> choice
-  [ try identifier
-  , try keywordT
-  , try integerLiteral
-  , try stringLiteral
-  , assign
-  , colon
-  , backslash
-  , openParen
-  , closeParen
-  , openBracket
-  , closeBracket
-  , lnewline
-  ] <* sc) <* eof
+tricuLexer :: Lexer [LToken]
+tricuLexer = do
+  sc
+  tokens <- many $ do
+    tok <- choice tricuLexer'
+    sc
+    pure tok
+  sc
+  eof
+  pure tokens
+    where
+      tricuLexer' = 
+        [ try lnewline
+        , try identifier
+        , try keywordT
+        , try integerLiteral
+        , try stringLiteral
+        , assign
+        , colon
+        , backslash
+        , openParen
+        , closeParen
+        , openBracket
+        , closeBracket
+        ]
 
-lexSapling :: String -> [LToken]
-lexSapling input = case runParser saplingLexer "" input of
-  Left err -> error $ "Lexical error:\n" ++ errorBundlePretty err
+lexTricu :: String -> [LToken]
+lexTricu input = case runParser tricuLexer "" input of
+  Left err -> errorWithoutStackTrace $ "Lexical error:\n" ++ errorBundlePretty err
   Right tokens -> tokens

src/Library.hs

@@ -1,47 +0,0 @@
-module Library where
-
-import Eval
-import Parser
-import Research
-
-import qualified Data.Map as Map
-
-library :: Map.Map String T
-library = evalSapling Map.empty $ parseSapling $ unlines 
-  [ "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)"
-  , "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)"
-  , "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)"
-  , "nonEmptyList = matchList false (\\y z : true)"
-  , "head = matchList t (\\hd tl : hd)"
-  , "tail = matchList t (\\hd tl : tl)"
-  , "isLeaf = (\\_ : triage true false false)"
-  , "listConcat = y (\\self : matchList (\\k : k) (\\h r k : pair h (self r k)))"
-  , "lAnd = triage (\\x : false) (\\_ x : x) (\\_ _ x : x)"
-  , "lOr = triage (\\x : x) (\\_ _ : true) (\\_ _ x : true)"
-  , "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))))" 
-  ]

src/Main.hs

@@ -1,22 +1,87 @@
 module Main where
 
-import Eval
-import Lexer
-import Library
-import Parser
-import REPL (repl)
+import Eval                   (evalTricu, result)
+import FileEval
+import Parser                 (parseTricu)
+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 = do
-  putStrLn "Welcome to the Sapling Interpreter"
-  putStrLn "You can exit at any time by typing and entering: "
-  putStrLn ":_exit"
-  repl library
+  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
 
-runSapling :: String -> T
-runSapling s = result (evalSapling Map.empty $ parseSapling s)
-runSaplingEnv env s = result (evalSapling env $ parseSapling s)
+runTricu :: String -> T
+runTricu input =
+  let asts     = parseTricu input
+      finalEnv = evalTricu Map.empty asts
+   in result finalEnv

src/Parser.hs

@@ -1,255 +1,304 @@
 module Parser where
 
-import Debug.Trace
 import Lexer
-import Research hiding (toList)
-import Control.Exception (throw)
+import Research
+
+import Control.Monad (void)
+import Control.Monad.State
 import Data.List.NonEmpty (toList)
-import qualified Data.Set as Set
-import Data.Void
+import Data.Void (Void)
 import Text.Megaparsec
-import Text.Megaparsec.Char
-import Text.Megaparsec.Error (errorBundlePretty, ParseErrorBundle)
+import Text.Megaparsec.Error (ParseErrorBundle, errorBundlePretty)
+import qualified Data.Set as Set
 
-type Parser = Parsec Void [LToken]
+data PState = PState
+  { parenDepth  :: Int
+  , bracketDepth :: Int
+  } deriving (Show)
 
-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)
+type ParserM = StateT PState (Parsec Void [LToken])
 
-parseSapling :: String -> [SaplingAST]
-parseSapling input =
-  let nonEmptyLines = filter (not . null) (lines input)
-  in map parseSingle nonEmptyLines
+satisfyM :: (LToken -> Bool) -> ParserM LToken
+satisfyM f = do
+  token <- lift (satisfy f)
+  modify' (updateDepth token)
+  return token
 
-parseSingle :: String -> SaplingAST
-parseSingle input = case runParser parseExpression "" (lexSapling input) of
-  Left err -> error $ handleParseError err
-  Right ast -> ast
+updateDepth :: LToken -> PState -> PState
+updateDepth LOpenParen    st = st { parenDepth   = parenDepth st   + 1 }
+updateDepth LOpenBracket  st = st { bracketDepth = bracketDepth st + 1 }
+updateDepth LCloseParen   st = st { parenDepth   = parenDepth st   - 1 }
+updateDepth LCloseBracket st = st { bracketDepth = bracketDepth st - 1 }
+updateDepth _ st = st
 
-scnParser :: Parser ()
-scnParser = skipMany (satisfy isNewline)
+topLevelNewline :: ParserM ()
+topLevelNewline = do
+  st <- get
+  if parenDepth st == 0 && bracketDepth st == 0
+    then void (satisfyM (== LNewline))
+    else fail "Top-level exit in nested context (paren or bracket)"
 
-parseExpression :: Parser SaplingAST
-parseExpression = choice
-  [ try parseFunction
-  , try parseLambda
-  , try parseLambdaExpression
-  , try parseListLiteral
-  , try parseApplication
-  , try parseTreeTerm
-  , parseLiteral
+parseProgram :: [LToken] -> Either (ParseErrorBundle [LToken] Void) [TricuAST]
+parseProgram tokens =
+  runParser (evalStateT (parseProgramM <* finalizeDepth <* eof) (PState 0 0)) "" tokens
+
+parseSingleExpr :: [LToken] -> Either (ParseErrorBundle [LToken] Void) TricuAST
+parseSingleExpr tokens =
+  runParser (evalStateT (scnParserM *> parseExpressionM <* finalizeDepth <* eof) (PState 0 0)) "" tokens
+
+finalizeDepth :: ParserM ()
+finalizeDepth = do
+  st <- get
+  case (parenDepth st, bracketDepth st) of
+    (0, 0) -> pure ()
+    (p, b) -> fail $ "Unmatched tokens: " ++ show (p, b)
+
+parseTricu :: String -> [TricuAST]
+parseTricu input =
+  case lexTricu input of
+    [] -> []
+    toks ->
+      case parseProgram toks of
+        Left err   -> errorWithoutStackTrace (handleParseError err)
+        Right asts -> asts
+
+parseSingle :: String -> TricuAST
+parseSingle input =
+  case lexTricu input of
+    [] -> SEmpty
+    toks ->
+      case parseSingleExpr toks of
+        Left err -> errorWithoutStackTrace (handleParseError err)
+        Right ast -> ast
+
+parseProgramM :: ParserM [TricuAST]
+parseProgramM = do
+  skipMany topLevelNewline
+  exprs <- sepEndBy parseOneExpression (some topLevelNewline)
+  skipMany topLevelNewline
+  return exprs
+
+parseOneExpression :: ParserM TricuAST
+parseOneExpression = scnParserM *> parseExpressionM
+
+scnParserM :: ParserM ()
+scnParserM = skipMany $ do
+  t  <- lookAhead anySingle
+  st <- get
+  if | (parenDepth st > 0 || bracketDepth st > 0) && case t of
+         LNewline -> True
+         _        -> False -> void $ satisfyM $ \case
+           LNewline -> True
+           _        -> False
+     | otherwise -> fail "In nested context or no space token" <|> empty
+
+
+eofM :: ParserM ()
+eofM = lift eof
+
+parseExpressionM :: ParserM TricuAST
+parseExpressionM = choice
+  [ try parseFunctionM
+  , try parseLambdaM
+  , try parseLambdaExpressionM
+  , try parseListLiteralM
+  , try parseApplicationM
+  , try parseTreeTermM
+  , parseLiteralM
   ]
 
-parseFunction :: Parser SaplingAST
-parseFunction = do
-  LIdentifier name <- satisfy isIdentifier
-  args <- many (satisfy isIdentifier)
-  satisfy (== LAssign)
-  body <- parseExpression
-  return (SFunc name (map getIdentifier args) body)
+parseFunctionM :: ParserM TricuAST
+parseFunctionM = do
+  LIdentifier name <- satisfyM $ \case
+    LIdentifier _ -> True
+    _             -> False
+  args <- many $ satisfyM $ \case
+    LIdentifier _ -> True
+    _             -> False
+  _    <- satisfyM (== LAssign)
+  scnParserM
+  body <- parseExpressionM
+  pure (SFunc name (map getIdentifier args) body)
 
-parseAtomicBase :: Parser SaplingAST
-parseAtomicBase = choice
-    [ try parseVarWithoutAssignment
-    , parseTreeLeaf
-    , parseGrouped
-    ]
-parseVarWithoutAssignment :: Parser SaplingAST
-parseVarWithoutAssignment = do
-    LIdentifier name <- satisfy isIdentifier
-    if (name == "t" || name == "__result")
-    then fail $ "Reserved keyword: " ++ name ++ " cannot be assigned."
-    else notFollowedBy (satisfy (== LAssign)) *> return (SVar name)
+parseLambdaM :: ParserM TricuAST
+parseLambdaM =
+  between (satisfyM (== LOpenParen)) (satisfyM (== LCloseParen)) $ do
+    _     <- satisfyM (== LBackslash)
+    param <- satisfyM $ \case
+      LIdentifier _ -> True
+      _             -> False
+    rest  <- many $ satisfyM $ \case
+      LIdentifier _ -> True
+      _             -> False
+    _     <- satisfyM (== LColon)
+    scnParserM
+    body <- parseLambdaExpressionM
+    let nested = foldr (\v acc -> SLambda [getIdentifier v] acc) body rest
+    pure (SLambda [getIdentifier param] nested)
 
-parseLambda :: Parser SaplingAST
-parseLambda = between (satisfy (== LOpenParen)) (satisfy (== LCloseParen)) $ do
-  satisfy (== LBackslash)
-  param    <- satisfy isIdentifier
-  rest     <- many (satisfy isIdentifier)
-  satisfy (== LColon)
-  body     <- parseLambdaExpression
-  let nestedLambda = foldr (\v acc -> SLambda [v] acc) body (map getIdentifier rest)
-  return (SLambda [getIdentifier param] nestedLambda)
-
-parseLambdaExpression :: Parser SaplingAST
-parseLambdaExpression = choice
-  [ try parseLambdaApplication
-  , parseAtomicLambda
+parseLambdaExpressionM :: ParserM TricuAST
+parseLambdaExpressionM = choice
+  [ try parseLambdaApplicationM
+  , parseAtomicLambdaM
   ]
 
-parseAtomicLambda :: Parser SaplingAST
-parseAtomicLambda = choice
-  [ parseVar
-  , parseTreeLeaf
-  , parseLiteral
-  , parseListLiteral
-  , try parseLambda
-  , between (satisfy (== LOpenParen)) (satisfy (== LCloseParen)) parseLambdaExpression
+parseAtomicLambdaM :: ParserM TricuAST
+parseAtomicLambdaM = choice
+  [ parseVarM
+  , parseTreeLeafM
+  , parseLiteralM
+  , parseListLiteralM
+  , try parseLambdaM
+  , between (satisfyM (== LOpenParen)) (satisfyM (== LCloseParen)) parseLambdaExpressionM
   ]
 
-parseApplication :: Parser SaplingAST
-parseApplication = do
-  func <- parseAtomicBase
-  args <- many parseAtomic
-  return $ foldl (\acc arg -> SApp acc arg) func args
+parseApplicationM :: ParserM TricuAST
+parseApplicationM = do
+  func <- parseAtomicBaseM
+  scnParserM
+  args <- many $ do
+    scnParserM
+    arg <- parseAtomicM
+    return arg
+  return $ foldl SApp func args
 
-parseLambdaApplication :: Parser SaplingAST
-parseLambdaApplication = do
-  func <- parseAtomicLambda
-  args <- many parseAtomicLambda
-  return $ foldl (\acc arg -> SApp acc arg) func args
+parseLambdaApplicationM :: ParserM TricuAST
+parseLambdaApplicationM = do
+  func <- parseAtomicLambdaM
+  scnParserM
+  args <- many $ do
+    arg <- parseAtomicLambdaM
+    scnParserM
+    pure arg
+  pure $ foldl SApp func args
 
-isTreeTerm :: SaplingAST -> Bool
-isTreeTerm TLeaf = True
-isTreeTerm (TStem _) = True
-isTreeTerm (TFork _ _) = True
-isTreeTerm _ = False
+parseAtomicBaseM :: ParserM TricuAST
+parseAtomicBaseM = choice
+  [ parseTreeLeafM
+  , parseGroupedM
+  ]
 
-parseTreeLeaf :: Parser SaplingAST
-parseTreeLeaf = satisfy isKeywordT *> notFollowedBy (satisfy (== LAssign)) *> pure TLeaf
+parseTreeLeafM :: ParserM TricuAST
+parseTreeLeafM = do
+  _ <- satisfyM $ \case
+    LKeywordT -> True
+    _         -> False
+  notFollowedBy $ lift $ satisfy (== LAssign)
+  pure TLeaf
+
+parseTreeTermM :: ParserM TricuAST
+parseTreeTermM = do
+  base <- parseTreeLeafOrParenthesizedM
+  rest <- many parseTreeLeafOrParenthesizedM
+  pure (foldl combine base rest)
+  where
+    combine acc next
+      | TLeaf     <- acc = TStem next
+      | TStem t   <- acc = TFork t next
+      | TFork _ _ <- acc = TFork acc next
+
+parseTreeLeafOrParenthesizedM :: ParserM TricuAST
+parseTreeLeafOrParenthesizedM = choice
+  [ between (satisfyM (== LOpenParen)) (satisfyM (== LCloseParen)) parseTreeTermM
+  , parseTreeLeafM
+  ]
+
+parseAtomicM :: ParserM TricuAST
+parseAtomicM = choice
+  [ parseVarM
+  , parseTreeLeafM
+  , parseListLiteralM
+  , parseGroupedM
+  , parseLiteralM
+  ]
+
+parseGroupedM :: ParserM TricuAST
+parseGroupedM = between (satisfyM (== LOpenParen)) (satisfyM (== LCloseParen)) $
+  scnParserM *> parseExpressionM <* scnParserM
+
+parseLiteralM :: ParserM TricuAST
+parseLiteralM = choice
+  [ parseIntLiteralM
+  , parseStrLiteralM
+  ]
+
+parseListLiteralM :: ParserM TricuAST
+parseListLiteralM = do
+  _        <- satisfyM (== LOpenBracket)
+  elements <- many $ do
+    scnParserM
+    parseListItemM
+  scnParserM
+  _        <- satisfyM (== LCloseBracket)
+  pure (SList elements)
+
+parseListItemM :: ParserM TricuAST
+parseListItemM = choice
+  [ parseGroupedItemM
+  , parseListLiteralM
+  , parseSingleItemM
+  ]
+
+parseGroupedItemM :: ParserM TricuAST
+parseGroupedItemM = do
+  _     <- satisfyM (== LOpenParen)
+  inner <- parseExpressionM
+  _     <- satisfyM (== LCloseParen)
+  pure inner
+
+parseSingleItemM :: ParserM TricuAST
+parseSingleItemM = do
+  token <- satisfyM $ \case
+    LIdentifier _ -> True
+    LKeywordT     -> True
+    _             -> False
+  case token of
+    LIdentifier name -> pure (SVar name)
+    LKeywordT        -> pure TLeaf
+    _                -> fail "Unexpected token in list item"
+
+parseVarM :: ParserM TricuAST
+parseVarM = do
+  LIdentifier name <- satisfyM $ \case
+    LIdentifier _ -> True
+    _             -> False
+  if name == "t" || name == "__result"
+    then fail ("Reserved keyword: " ++ name ++ " cannot be assigned.")
+    else pure (SVar name)
+
+parseIntLiteralM :: ParserM TricuAST
+parseIntLiteralM = do
+  LIntegerLiteral value <- satisfyM $ \case
+    LIntegerLiteral _ -> True
+    _                 -> False
+  pure (SInt value)
+
+parseStrLiteralM :: ParserM TricuAST
+parseStrLiteralM = do
+  LStringLiteral value <- satisfyM $ \case 
+    LStringLiteral _ -> True
+    _ -> False
+  pure (SStr value)
 
 getIdentifier :: LToken -> String
 getIdentifier (LIdentifier name) = name
-getIdentifier _ = error "Expected identifier"
+getIdentifier _                  = errorWithoutStackTrace "Expected identifier"
 
-parseTreeTerm :: Parser SaplingAST
-parseTreeTerm = do
-  base <- parseTreeLeafOrParenthesized
-  rest <- many parseTreeLeafOrParenthesized
-  pure $ foldl combine base rest
-  where
-    combine acc next = case acc of
-      TLeaf -> TStem next
-      TStem t -> TFork t next
-      TFork _ _ -> TFork acc next
-
-parseTreeLeafOrParenthesized :: Parser SaplingAST
-parseTreeLeafOrParenthesized = choice
-  [ between (satisfy (== LOpenParen)) (satisfy (== LCloseParen)) parseTreeTerm
-  , parseTreeLeaf
-  ]
-
-foldTree :: [SaplingAST] -> SaplingAST
-foldTree [] = TLeaf
-foldTree [x] = x
-foldTree (x:y:rest) = TFork x (foldTree (y:rest))
-
-parseAtomic :: Parser SaplingAST
-parseAtomic = choice
-  [ parseVar
-  , parseTreeLeaf
-  , parseListLiteral
-  , parseGrouped
-  , parseLiteral
-  ]
-
-parseGrouped :: Parser SaplingAST
-parseGrouped = between (satisfy (== LOpenParen)) (satisfy (== LCloseParen)) parseExpression
-
-parseLiteral :: Parser SaplingAST
-parseLiteral = choice
-  [ parseIntLiteral
-  , parseStrLiteral
-  ]
-
-parens :: Parser SaplingAST -> Parser SaplingAST
-parens p = do
-  satisfy (== LOpenParen)
-  result <- p
-  satisfy (== LCloseParen)
-  return result
-
-parseListLiteral :: Parser SaplingAST
-parseListLiteral = do
-  satisfy (== LOpenBracket)
-  elements <- many parseListItem
-  satisfy (== LCloseBracket)
-  return (SList elements)
-
-parseListItem :: Parser SaplingAST
-parseListItem = choice
-  [ parseGroupedItem
-  , parseListLiteral
-  , parseSingleItem
-  ]
-
-parseGroupedItem :: Parser SaplingAST
-parseGroupedItem = do
-  satisfy (== LOpenParen)
-  inner <- parseExpression
-  satisfy (== LCloseParen)
-  return inner
-
-parseSingleItem :: Parser SaplingAST
-parseSingleItem = do
-  token <- satisfy isListItem
-  case token of
-    LIdentifier name -> return (SVar name)
-    LKeywordT -> return TLeaf
-    _ -> fail "Unexpected token in list item"
-
-isListItem :: LToken -> Bool
-isListItem (LIdentifier _) = True
-isListItem LKeywordT = True
-isListItem _ = False
-
-parseVar :: Parser SaplingAST
-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 = do
-  LIntegerLiteral value <- satisfy isIntegerLiteral
-  return (SInt value)
-
-parseStrLiteral :: Parser SaplingAST
-parseStrLiteral = do
-  LStringLiteral value <- satisfy isStringLiteral
-  return (SStr value)
-
--- Boolean Helpers
-isKeywordT (LKeywordT) = True
-isKeywordT _ = False
-isIdentifier (LIdentifier _) = True
-isIdentifier _ = False
-isIntegerLiteral (LIntegerLiteral _) = True
-isIntegerLiteral _ = False
-isStringLiteral (LStringLiteral _) = True
-isStringLiteral _ = False
-isLiteral (LIntegerLiteral _) = True
-isLiteral (LStringLiteral _) = True
-isLiteral _ = False
-isNewline (LNewline) = True
-isNewline _ = False
-
--- Error Handling
 handleParseError :: ParseErrorBundle [LToken] Void -> String
 handleParseError bundle =
   let errors = bundleErrors bundle
-      errorList = toList errors
-      formattedErrors = map showError errorList
+      formattedErrors = map formatError (Data.List.NonEmpty.toList errors)
   in unlines ("Parse error(s) encountered:" : formattedErrors)
 
-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)
-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)
-
+formatError :: ParseError [LToken] Void -> String
+formatError (TrivialError offset unexpected expected) =
+  let unexpectedMsg = case unexpected of
+        Just x  -> "unexpected token " ++ show x
+        Nothing -> "unexpected end of input"
+      expectedMsg = if null expected
+        then ""
+        else "expected " ++ show (Set.toList expected)
+  in "Parse error at offset " ++ show offset ++ ": " ++ unexpectedMsg ++
+     if null expectedMsg then "" else " " ++ expectedMsg
+formatError (FancyError offset _) =
+  "Parse error at offset " ++ show offset ++ ": unexpected FancyError"

src/REPL.hs

@@ -1,42 +1,68 @@
 module REPL where
 
 import Eval
+import FileEval
 import Lexer
 import Parser
 import Research
 
-import Data.List                 (intercalate)
-import qualified Data.Map as Map
+import Control.Exception         (SomeException, catch)
+import Control.Monad.IO.Class    (liftIO)
+import Data.Char                 (isSpace)
+import Data.List                 (dropWhile, dropWhileEnd, intercalate)
 import System.Console.Haskeline
-import System.IO                 (hFlush, stdout)
 
-repl :: Map.Map String T -> IO ()
+import qualified Data.Map as Map
+
+repl :: Env -> IO ()
 repl env = runInputT defaultSettings (loop env)
   where
-    loop :: Map.Map String T -> InputT IO ()
+    loop :: Env -> InputT IO ()
     loop env = do
-      minput <- getInputLine "sapling < "
-      case minput of
-        Nothing -> outputStrLn "Goodbye!"
-        Just ":_exit" -> outputStrLn "Goodbye!"
-        Just "" -> do
+      minput <- getInputLine "tricu < "
+      if
+        | Nothing <- minput                     -> outputStrLn "Exiting tricu"
+        | Just s  <- minput, strip s == "!exit" -> outputStrLn "Exiting tricu"
+        | Just s  <- minput, strip s == ""      -> do
           outputStrLn ""
           loop env
-        Just input -> do
-          let clearEnv = Map.delete "__result" env
-              newEnv   = evalSingle clearEnv (parseSingle input)
-          case Map.lookup "__result" newEnv of
-            Just r -> do
-              outputStrLn $ "sapling > " ++ show r
-              outputStrLn $ "DECODE -: " ++ decodeResult r
-            Nothing -> return ()
-          loop newEnv
+        | Just s  <- minput, strip s == "!load" -> do
+          path <- getInputLine "File path to load < "
+          if
+            | Nothing <- path -> do
+              outputStrLn "No input received; stopping import."
+              loop env
+            | Just p  <- path -> do
+              loadedEnv <- liftIO $ evaluateFileWithContext env (strip p) `catch` \e -> errorHandler env e
+              loop $ Map.delete "__result" (Map.union loadedEnv env)
+        | Just s <- minput -> do
+          if
+            | take 2 s == "--" -> loop env
+            | otherwise -> do
+              newEnv <- liftIO $ processInput env s `catch` errorHandler env
+              loop newEnv
+
+    processInput :: Env -> String -> IO Env
+    processInput env input = do
+      let asts   = parseTricu input
+          newEnv = evalTricu env asts
+      if
+        | Just r <- Map.lookup "__result" newEnv -> do
+          putStrLn $ "tricu > " ++ decodeResult r
+        | otherwise -> 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 _ -> ""
+decodeResult tc
+  | Right num  <- toNumber tc = show num
+  | Right str  <- toString tc = "\"" ++ str ++ "\""
+  | Right list <- toList tc   = "[" ++ intercalate ", " (map decodeResult list) ++ "]"
+  | otherwise                 = 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.Map (Map)
+import Data.List                 (intercalate)
+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)
+
+-- Lexer Tokens
+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
@@ -17,29 +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
-
-_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 = Fork (Stem (Stem Leaf)) Leaf 
-
 -- Booleans
 _false :: T
 _false = Leaf
@@ -87,7 +108,31 @@ toList (Fork x rest) = case toList rest of
   Left err -> Left err
 toList _ = Left "Invalid Tree Calculus list"
 
--- Utility
+-- 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)
+
 toAscii :: T -> String
 toAscii tree = go tree "" True
   where
@@ -102,41 +147,4 @@ toAscii tree = go tree "" True
         ++ go left (prefix ++ (if isLast then "    " else "|   ")) False
         ++ go right (prefix ++ (if isLast then "    " else "|   ")) True
 
-rules :: IO ()
-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"
+-- Utility

test/Spec.hs

@@ -1,11 +1,14 @@
 module Main where
 
 import Eval
+import FileEval
 import Lexer
-import Library
 import Parser
+import REPL
 import Research
+
 import Control.Exception (evaluate, try, SomeException)
+import Control.Monad.IO.Class (liftIO)
 import Test.Tasty
 import Test.Tasty.HUnit
 import Test.Tasty.QuickCheck
@@ -17,17 +20,17 @@ import qualified Data.Set as Set
 main :: IO ()
 main = defaultMain tests
 
-runSapling :: String -> String
-runSapling s = show $ result (evalSapling Map.empty $ parseSapling s)
+runTricu :: String -> String
+runTricu s = show $ result (evalTricu Map.empty $ parseTricu s)
 
 tests :: TestTree
-tests = testGroup "Sapling Tests"
+tests = testGroup "Tricu Tests"
   [ lexerTests
   , parserTests
-  , integrationTests
   , evaluationTests
   , lambdaEvalTests
-  , propertyTests
+  , libraryTests
+  , fileEvaluationTests
   ]
 
 lexerTests :: TestTree
@@ -35,47 +38,42 @@ lexerTests = testGroup "Lexer Tests"
   [ testCase "Lex simple identifiers" $ do
       let input = "x a b = 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
       let input = "t t t"
           expect = Right [LKeywordT, LKeywordT, LKeywordT]
-      runParser saplingLexer "" input @?= expect
+      runParser tricuLexer "" input @?= expect
   , testCase "Lex escaped characters in strings" $ do
       let input = "\"hello\\nworld\""
           expect = Right [LStringLiteral "hello\\nworld"]
-      runParser saplingLexer "" input @?= expect
+      runParser tricuLexer "" input @?= expect
   , testCase "Lex mixed literals" $ do
       let input = "t \"string\" 42"
           expect = Right [LKeywordT, LStringLiteral "string", LIntegerLiteral 42]
-      runParser saplingLexer "" input @?= expect
+      runParser tricuLexer "" input @?= expect
   , testCase "Lex invalid token" $ do
-      let input = "$invalid"
-      case runParser saplingLexer "" input of
+      let input = "&invalid"
+      case runParser tricuLexer "" input of
         Left _ -> return ()
         Right _ -> assertFailure "Expected lexer to fail on invalid token"
   , testCase "Drop trailing whitespace in definitions" $ do
       let input = "x = 5 "
           expect = [LIdentifier "x",LAssign,LIntegerLiteral 5]
-      case (runParser saplingLexer "" input) of
+      case (runParser tricuLexer "" input) of
         Left _ -> assertFailure "Failed to lex input"
         Right i -> i @?= expect
   , testCase "Error when using invalid characters in identifiers" $ do
-        case (runParser saplingLexer "" "__result = 5") of
+        case (runParser tricuLexer "" "__result = 5") of
           Left _ -> return ()
           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
-    --  let input = lexSapling "x = "
-    --  case (runParser parseExpression "" input) of
-    --    Left _ -> return ()
-    --    Right _ -> assertFailure "Expected failure on invalid input"
-  testCase "Error when assigning a value to T" $ do
-      let input = lexSapling "t = x"
-      case (runParser parseExpression "" input) of
-        Left _ -> return ()
+  [ testCase "Error when assigning a value to T" $ do
+      let tokens = lexTricu "t = x" 
+      case parseSingleExpr tokens of
+        Left  _ -> return ()
         Right _ -> assertFailure "Expected failure when trying to assign the value of T"
   , testCase "Parse function definitions" $ do
       let input = "x = (\\a b c : a)"
@@ -142,19 +140,15 @@ parserTests = testGroup "Parser Tests"
   , testCase "Grouping T terms with parentheses in function application" $ do
       let input  = "x = (\\a : a)\nx (t)"
           expect = [SFunc "x" [] (SLambda ["a"] (SVar "a")),SApp (SVar "x") TLeaf]
-      parseSapling input @?= expect
-  ]
-
-integrationTests :: TestTree
-integrationTests = testGroup "Integration Tests"
-  [ testCase "Combine lexer and parser" $ do
-      let input = "x = t t t"
-          expect = SFunc "x" [] (SApp (SApp TLeaf TLeaf) TLeaf)
-      parseSingle input @?= expect
-  , testCase "Complex Tree Calculus expression" $ do
-      let input = "t (t t t) t"
-          expect = SApp (SApp TLeaf (SApp (SApp TLeaf TLeaf) TLeaf)) TLeaf
-      parseSingle input @?= expect
+      parseTricu input @?= expect
+  , testCase "Comments 1" $ do
+      let input = "(t) (t) -- (t)"
+          expect = [SApp TLeaf TLeaf]
+      parseTricu input @?= expect
+  , testCase "Comments 2" $ do
+      let input = "(t) -- (t) -- (t)"
+          expect = [TLeaf]
+      parseTricu input @?= expect
   ]
 
 evaluationTests :: TestTree
@@ -182,16 +176,16 @@ evaluationTests = testGroup "Evaluation Tests"
         Fork (Fork (Stem Leaf) (Fork Leaf Leaf)) Leaf
   , testCase "Environment updates with definitions" $ do
       let input = "x = t\ny = x"
-          env = evalSapling Map.empty (parseSapling input)
+          env = evalTricu Map.empty (parseTricu input)
       Map.lookup "x" env @?= Just Leaf
       Map.lookup "y" env @?= Just Leaf
   , testCase "Variable substitution" $ do
       let input = "x = t t\ny = t x\ny"
-          env = evalSapling Map.empty (parseSapling input)
+          env = evalTricu Map.empty (parseTricu input)
       (result env) @?= Stem (Stem Leaf)
   , testCase "Multiline input evaluation" $ do
       let input = "x = t\ny = t t\nx"
-          env = evalSapling Map.empty (parseSapling input)
+          env = evalTricu Map.empty (parseTricu input)
       (result env) @?= Leaf
   , testCase "Evaluate string literal" $ do
       let input = "\"hello\""
@@ -211,110 +205,207 @@ evaluationTests = testGroup "Evaluation Tests"
                   \ z = y\n \
                   \ variablewithamuchlongername = z\n \
                   \ variablewithamuchlongername"
-          env = evalSapling Map.empty (parseSapling input)
+          env = evalTricu Map.empty (parseTricu input)
       (result env) @?= (Stem (Stem Leaf))
   , testCase "Evaluate variable shadowing" $ do
       let input = "x = t t\nx = t\nx"
-          env = evalSapling Map.empty (parseSapling input)
+          env = evalTricu Map.empty (parseTricu input)
       (result env) @?= Leaf
-    , testCase "Apply identity to Boolean Not" $ do
+  , testCase "Apply identity to Boolean Not" $ do
       let not = "(t (t (t t) (t t t)) t)"
       let input = "x = (\\a : a)\nx " ++ not
-          env = evalSapling Map.empty (parseSapling input)
+          env = evalTricu Map.empty (parseTricu input)
       result env @?= Fork (Fork (Stem Leaf) (Fork Leaf Leaf)) Leaf
-    , testCase "Constant function matches" $ do
-      let input = "k = (\\a b : a)\nk (t t) t"
-          env = evalSapling Map.empty (parseSapling input)
-      result env @?= Stem Leaf
-   , testCase "Boolean AND_ TF" $ do
-      let input = "and (t t) (t)"
-          env = evalSapling library (parseSapling input)
-      result env @?= Leaf
-   , testCase "Boolean AND_ FT" $ do
-      let input = "and (t) (t t)"
-          env = evalSapling library (parseSapling input)
-      result env @?= Leaf
-   , testCase "Boolean AND_ FF" $ do
-      let input = "and (t) (t)"
-          env = evalSapling library (parseSapling input)
-      result env @?= Leaf
-    , testCase "Boolean AND_ TT" $ do
-      let input = "and (t t) (t t)"
-          env = evalSapling library (parseSapling input)
-      result env @?= Stem Leaf
-    , testCase "Verifying Equality" $ do
-      let input = "equal (t t t) (t t t)"
-          env = evalSapling library (parseSapling input)
-      result env @?= Stem Leaf
   ]
 
 lambdaEvalTests :: TestTree
 lambdaEvalTests = testGroup "Lambda Evaluation Tests"
   [ testCase "Lambda Identity Function" $ do
       let input = "id = (\\x : x)\nid t"
-      runSapling input @?= "Leaf"
+      runTricu input @?= "Leaf"
   , testCase "Lambda Constant Function (K combinator)" $ do
       let input = "k = (\\x y : x)\nk t (t t)"
-      runSapling input @?= "Leaf"
+      runTricu input @?= "Leaf"
   , testCase "Lambda Application with Variable" $ do
       let input = "id = (\\x : x)\nval = t t\nid val"
-      runSapling input @?= "Stem Leaf"
+      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)"
-      runSapling input @?= "Leaf"
+      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"
-      runSapling input @?= "Leaf"
+      runTricu input @?= "Leaf"
   , testCase "Lambda with a complex body" $ do
       let input = "f = (\\x : t (t x))\nf t"
-      runSapling input @?= "Stem (Stem Leaf)"
+      runTricu input @?= "Stem (Stem Leaf)"
   , testCase "Lambda returning a function" $ do
       let input = "f = (\\x : (\\y : x))\ng = f t\ng (t t)"
-      runSapling input @?= "Leaf"
+      runTricu input @?= "Leaf"
   , testCase "Lambda with Shadowing" $ do
       let input = "f = (\\x : (\\x : x))\nf t (t t)"
-      runSapling input @?= "Stem Leaf"
+      runTricu input @?= "Stem Leaf"
    , testCase "Lambda returning another lambda" $ do
       let input = "k = (\\x : (\\y : x))\nk_app = k t\nk_app (t t)"
-      runSapling input @?= "Leaf"
+      runTricu input @?= "Leaf"
    , testCase "Lambda with free variables" $ do
       let input = "y = t t\nf = (\\x : y)\nf t"
-      runSapling input @?= "Stem Leaf"
+      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)"
-      runSapling input @?= "Stem (Stem Leaf)"
+      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)"
-      runSapling input @?= "Stem Leaf"
+      runTricu input @?= "Stem Leaf"
    , testCase "Lambda with nested application in the body" $ do
       let input = "f = (\\x : t (t (t x)))\nf t"
-      runSapling input @?= "Stem (Stem (Stem Leaf))"
+      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)"
-        runSapling input @?= "Fork Leaf (Stem Leaf)"
+        runTricu input @?= "Fork Leaf (Stem Leaf)"
     , testCase "Lambda applying a variable" $ do
         let input = "id = (\\x : x)\na = t t\nid a"
-        runSapling input @?= "Stem Leaf"
+        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"
-        runSapling input @?= "Leaf"
+        runTricu input @?= "Leaf"
   , testCase "Lambda with a string literal" $ do
         let input = "f = (\\x : x)\nf \"hello\""
-        runSapling 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))))"
+        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"
-        runSapling input @?= "Fork Leaf (Fork (Stem Leaf) (Fork Leaf (Fork (Stem Leaf) (Fork Leaf (Fork (Stem Leaf) Leaf)))))"
+        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)]"
-        runSapling input @?= "Fork Leaf (Fork (Stem Leaf) Leaf)"
+        runTricu input @?= "Fork Leaf (Fork (Stem Leaf) Leaf)"
   ]
 
-propertyTests :: TestTree
-propertyTests = testGroup "Property Tests"
-  [ testProperty "Lexing and parsing round-trip" $ \input ->
-      case runParser saplingLexer "" input of
-        Left _ -> property True
-        Right tokens -> case runParser parseExpression "" tokens of
-          Left _ -> property True
-          Right ast -> parseSingle input === ast
+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!\""
   ]

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

@@ -1,7 +1,7 @@
 cabal-version: 1.12
 
-name:           sapling
-version:        0.4.0
+name:           tricu
+version:        0.7.0
 description:    A micro-language for exploring Tree Calculus
 author:         James Eversole
 maintainer:     james@eversole.co
@@ -12,41 +12,45 @@ build-type:     Simple
 extra-source-files:
     README.md
 
-executable sapling
+executable tricu
   main-is: Main.hs
   hs-source-dirs:
       src
   default-extensions:
-      ConstraintKinds
-      DataKinds
-      DeriveGeneric
-      FlexibleContexts
-      FlexibleInstances
-      GeneralizedNewtypeDeriving
+      DeriveDataTypeable
+      LambdaCase
+      MultiWayIf
       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
-    Library
     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
+      LambdaCase
+      MultiWayIf
+      OverloadedStrings
   build-depends:       
     base
+    , cmdargs
     , containers
     , haskeline
     , megaparsec
@@ -54,11 +58,12 @@ test-suite sapling-tests
     , tasty
     , tasty-hunit
     , tasty-quickcheck
+    , text
   default-language:    Haskell2010
   other-modules:
     Eval
+    FileEval
     Lexer
-    Library
     Parser
     REPL
     Research