Release 0.6.0

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 +1,86 @@
+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: Set up cache for Nix
+        uses: actions/cache@v4
+        with:
+          path: |
+            /nix/store
+            /nix/var/nix/cache
+          key: nix-${{ hashFiles('flake.lock') }}
+          restore-keys: |
+            nix-
+
+      - 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: ${{ secrets.REGISTRY_PASSWORD }}
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+
+      - name: Set up cache for Nix
+        uses: actions/cache@v4
+        with:
+          path: |
+            /nix/store
+            /nix/var/nix/cache
+          key: nix-${{ hashFiles('flake.lock') }}
+          restore-keys: |
+            nix-
+  
+      - name: Build binary
+        run: |
+          nix build
+          ls -alh ./result/bin/tricu
+  
+      - name: Setup go for release actoin
+        uses: actions/setup-go@v5
+        with:
+          go-version: '>=1.20.1'
+  
+      - name: Release binary
+        uses: https://gitea.com/actions/release-action@main
+        with:
+          files: |-
+            ./result/bin/tricu
+          api_key: '${{ secrets.RELEASE_TOKEN }}'

.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 "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).
 
-- `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 term back to source code
+tricu < toSource not?
+tricu > "(t (t (t t) (t t t)) (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/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} =

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

@@ -2,139 +2,91 @@ 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 :: Env -> TricuAST -> Env
-evalSingle env term = case term of
+evalSingle env term
-    SFunc name [] body ->
+  | SFunc name [] body <- term =
-        let result = evalAST env body
+      let res = evalAST env body
-        in Map.insert name result env
+      in Map.insert "__result" res (Map.insert name res env)
-    SApp func arg ->
+  | SApp func arg <- term =
-        let result = apply (evalAST env func) (evalAST env arg)
+      let res = apply (evalAST env func) (evalAST env arg)
-        in Map.insert "__result" result env
+      in Map.insert "__result" res env
-    SVar name -> case Map.lookup name env of
+  | SVar name <- term =
-        Just value -> Map.insert "__result" value env
+      case Map.lookup name env of
-        Nothing -> error $ "Variable " ++ name ++ " not defined"
+        Just v  -> Map.insert "__result" v env
-    _ ->
+        Nothing -> errorWithoutStackTrace $ "Variable " ++ name ++ " not defined"
-        let result = evalAST env term
+  | otherwise =
-        in Map.insert "__result" result env
+      Map.insert "__result" (evalAST env term) env
 
-evalSapling :: Map String T -> [SaplingAST] -> Map String T
+evalTricu :: Env -> [TricuAST] -> Env
-evalSapling env [] = env
+evalTricu env []     = env
-evalSapling env [lastLine] =
+evalTricu env [x]    =
-    let
+  let updatedEnv = evalSingle env x
-        lastLineNoLambda = eliminateLambda lastLine
+  in Map.insert "__result" (result updatedEnv) updatedEnv
-        updatedEnv = evalSingle env lastLineNoLambda
+evalTricu env (x:xs) =
-    in Map.insert "__result" (result updatedEnv) updatedEnv
+  evalTricu (evalSingle env x) xs
-evalSapling env (line:rest) =
-    let
-        lineNoLambda = eliminateLambda line
-        updatedEnv = evalSingle env lineNoLambda
-    in evalSapling updatedEnv rest
 
-evalAST :: Map String T -> SaplingAST -> T
+evalAST :: Env -> TricuAST -> T
-evalAST env term = case term of
+evalAST env term
-    SVar name ->
+  | SLambda _ _ <- term = evalAST env (elimLambda term)
-        case Map.lookup name env of
+  | SVar   name <- term = evalVar name
-            Just value -> value
+  | TLeaf       <- term = Leaf
-            Nothing -> error $ "Variable " ++ name ++ " not defined"
+  | TStem  t    <- term = Stem (evalAST env t)
-    TLeaf -> Leaf
+  | TFork  t u  <- term = Fork (evalAST env t) (evalAST env u)
-    TStem t ->
+  | SApp   t u  <- term = apply (evalAST env t) (evalAST env u)
-        Stem (evalAST env t)
+  | SStr   s    <- term = ofString s
-    TFork t1 t2 ->
+  | SInt   n    <- term = ofNumber n
-        Fork (evalAST env t1) (evalAST env t2)
+  | SList  xs   <- term = ofList (map (evalAST env) xs)
-    SApp t1 t2 ->
+  | SEmpty      <- term = Leaf
-        apply (evalAST env t1) (evalAST env t2)
+  | otherwise           = errorWithoutStackTrace "Unexpected AST term"
-    SStr str -> toString str
+    where
-    SInt num -> toNumber num
+      evalVar name = Map.findWithDefault
-    SList elems -> toList (map (evalAST Map.empty) elems)
+        (errorWithoutStackTrace $ "Variable " ++ name ++ " not defined")
-    SFunc name args body ->
+        name env
-        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
+-- https://github.com/barry-jay-personal/typed_tree_calculus/blob/main/typed_program_analysis.pdf
+-- 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
+
+    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
+
+    _S = parseSingle "t (t (t t t)) t"
+    _K = parseSingle "t t"
+    _I = parseSingle "t (t (t t)) t"
+    
+    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
+
+result :: Env -> T
 result r = case Map.lookup "__result" r of
-    Just a -> a
+  Just a -> a
-    Nothing -> error "No __result field found in provided environment"
+  Nothing -> errorWithoutStackTrace "No __result field found in provided environment"
-
-
-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 (SFunc n vs b) =
-    SFunc n vs (eliminateLambda b)
-eliminateLambda other = other
-
-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 (SApp f args) = lambdaToT x f
-lambdaToT x body
-    | not (isFree x body) =
-        SApp tK body
-    | otherwise =
-        SApp
-        (SApp tS (lambdaToT x body))
-        tLeaf
-
-tLeaf :: SaplingAST
-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 (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 x = Set.member x . freeVars
-
-toAST :: T -> SaplingAST
-toAST Leaf = TLeaf
-toAST (Stem a) = TStem (toAST a)
-toAST (Fork a b) = TFork (toAST a) (toAST b)
-
-tI :: SaplingAST
-tI = toAST _I
-
-tK :: SaplingAST
-tK = toAST _K
-
-tS :: SaplingAST
-tS = toAST _S
-

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 +1,28 @@
 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 
+              <|> 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)
@@ -41,11 +36,8 @@ 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 +64,38 @@ lnewline :: Lexer LToken
 lnewline = char '\n' *> pure LNewline
 
 sc :: Lexer ()
-sc = skipMany (char ' ' <|> char '\t')
+sc = space
+  (void $ takeWhile1P (Just "space") (\c -> c == ' ' || c == '\t'))
+  (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 lnewline
-  , lnewline
+        , try identifier
-  ] <* sc) <* eof
+        , try keywordT
+        , 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 +1,87 @@
 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 input =
+  let asts     = parseTricu input
+      finalEnv = evalTricu Map.empty asts
+   in result finalEnv

src/Parser.hs

@@ -1,254 +1,304 @@
 module Parser where
 
-import Debug.Trace
-
 import Lexer
-import Research hiding (toList)
+import Research
 
-import Control.Exception (throw)
+import Control.Monad (void)
+import Control.Monad.State
 import Data.List.NonEmpty (toList)
-import qualified Data.Set as Set
+import Data.Void (Void)
-import Data.Void
 import Text.Megaparsec
-import Text.Megaparsec.Char
+import Text.Megaparsec.Error (ParseErrorBundle, errorBundlePretty)
-import Text.Megaparsec.Error (errorBundlePretty, ParseErrorBundle)
+import qualified Data.Set as Set
 
-type Parser = Parsec Void [LToken]
+data PState = PState
-data SaplingAST
+  { parenDepth  :: Int
-  = SVar    String
+  , bracketDepth :: Int
-  | SInt    Int
+  } deriving (Show)
-  | 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 ParserM = StateT PState (Parsec Void [LToken])
-parseSapling input =
-  let nonEmptyLines = filter (not . null) (lines input)
-  in map parseSingle nonEmptyLines
 
-parseSingle :: String -> SaplingAST
+satisfyM :: (LToken -> Bool) -> ParserM LToken
-parseSingle "" = error "Empty input provided to parseSingle"
+satisfyM f = do
-parseSingle input = case runParser parseExpression "" (lexSapling input) of
+  token <- lift (satisfy f)
-  Left  err -> error $ handleParseError err
+  modify' (updateDepth token)
-  Right ast -> ast
+  return token
 
-scnParser :: Parser ()
+updateDepth :: LToken -> PState -> PState
-scnParser = skipMany (satisfy isNewline)
+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
 
-parseExpression :: Parser SaplingAST
+topLevelNewline :: ParserM ()
-parseExpression = choice
+topLevelNewline = do
-  [ try parseFunction
+  st <- get
-  , try parseLambda
+  if parenDepth st == 0 && bracketDepth st == 0
-  , try parseListLiteral
+    then void (satisfyM (== LNewline))
-  , try parseApplication
+    else fail "Top-level exit in nested context (paren or bracket)"
-  , 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
+parseFunctionM :: ParserM TricuAST
-parseFunction = do
+parseFunctionM = do
-  LIdentifier name <- satisfy isIdentifier
+  LIdentifier name <- satisfyM $ \case
-  args <- many (satisfy isIdentifier)
+    LIdentifier _ -> True
-  satisfy (== LAssign)
+    _             -> False
-  body <- parseExpression
+  args <- many $ satisfyM $ \case
-  return (SFunc name (map getIdentifier args) body)
+    LIdentifier _ -> True
+    _             -> False
+  _    <- satisfyM (== LAssign)
+  scnParserM
+  body <- parseExpressionM
+  pure (SFunc name (map getIdentifier args) body)
 
-parseLambda :: Parser SaplingAST
+parseLambdaM :: ParserM TricuAST
-parseLambda = between (satisfy (== LOpenParen)) (satisfy (== LCloseParen)) $ do
+parseLambdaM =
-  satisfy (== LBackslash)
+  between (satisfyM (== LOpenParen)) (satisfyM (== LCloseParen)) $ do
-  param <- satisfy isIdentifier
+    _     <- satisfyM (== LBackslash)
-  rest <- many (satisfy isIdentifier)
+    param <- satisfyM $ \case
-  satisfy (== LColon)
+      LIdentifier _ -> True
-  body <- parseLambdaExpression
+      _             -> False
-  let nestedLambda = foldr (\v acc -> SLambda [v] acc) body (map getIdentifier rest)
+    rest  <- many $ satisfyM $ \case
-  return (SLambda [getIdentifier param] nestedLambda)
+      LIdentifier _ -> True
+      _             -> False
+    _     <- satisfyM (== LColon)
+    scnParserM
+    body <- parseLambdaExpressionM
+    let nested = foldr (\v acc -> SLambda [getIdentifier v] acc) body rest
+    pure (SLambda [getIdentifier param] nested)
 
-parseLambdaExpression :: Parser SaplingAST
+parseLambdaExpressionM :: ParserM TricuAST
-parseLambdaExpression = choice
+parseLambdaExpressionM = choice
-  [ try parseLambdaApplication
+  [ try parseLambdaApplicationM
-  , parseAtomicLambda
+  , parseAtomicLambdaM
   ]
 
-parseAtomicLambda :: Parser SaplingAST
+parseAtomicLambdaM :: ParserM TricuAST
-parseAtomicLambda = choice
+parseAtomicLambdaM = choice
-  [ parseVar
+  [ parseVarM
-  , parseTreeLeaf
+  , parseTreeLeafM
-  , parseLiteral
+  , parseLiteralM
-  , parseListLiteral
+  , parseListLiteralM
-  , between (satisfy (== LOpenParen)) (satisfy (== LCloseParen)) parseLambdaExpression
+  , try parseLambdaM
+  , between (satisfyM (== LOpenParen)) (satisfyM (== LCloseParen)) parseLambdaExpressionM
   ]
 
-parseApplication :: Parser SaplingAST
+parseApplicationM :: ParserM TricuAST
-parseApplication = do
+parseApplicationM = do
-  func <- parseAtomicBase
+  func <- parseAtomicBaseM
-  args <- many parseAtomic
+  scnParserM
-  return $ foldl (\acc arg -> SApp acc arg) func args
+  args <- many $ do
+    scnParserM
+    arg <- parseAtomicM
+    return arg
+  return $ foldl SApp func args
 
-parseLambdaApplication :: Parser SaplingAST
+parseLambdaApplicationM :: ParserM TricuAST
-parseLambdaApplication = do
+parseLambdaApplicationM = do
-    func <- parseAtomicLambda
+  func <- parseAtomicLambdaM
-    args <- many parseAtomicLambda
+  scnParserM
-    return $ foldl (\acc arg -> SApp acc arg) func args
+  args <- many $ do
+    arg <- parseAtomicLambdaM
+    scnParserM
+    pure arg
+  pure $ foldl SApp func args
 
-isTreeTerm :: SaplingAST -> Bool
+parseAtomicBaseM :: ParserM TricuAST
-isTreeTerm TLeaf       = True
+parseAtomicBaseM = choice
-isTreeTerm (TStem _)   = True
+  [ parseTreeLeafM
-isTreeTerm (TFork _ _) = True
+  , parseGroupedM
-isTreeTerm _           = False
-
-parseAtomicBase :: Parser SaplingAST
-parseAtomicBase = choice
-  [ parseVar
-  , parseTreeLeaf
-  , parseGrouped
   ]
 
-parseTreeLeaf :: Parser SaplingAST
+parseTreeLeafM :: ParserM TricuAST
-parseTreeLeaf = satisfy isKeywordT *> notFollowedBy (satisfy (== LAssign)) *> pure TLeaf
+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
-
-esNewline        (LNewline)          = True
-isNewline                         _  = False
-
--- Error Handling
 handleParseError :: ParseErrorBundle [LToken] Void -> String
 handleParseError bundle =
   let errors = bundleErrors bundle
-      errorList = toList errors
+      formattedErrors = map formatError (Data.List.NonEmpty.toList errors)
-      formattedErrors = map showError errorList
   in unlines ("Parse error(s) encountered:" : formattedErrors)
 
-showError :: ParseError [LToken] Void -> String
+formatError :: ParseError [LToken] Void -> String
-showError (TrivialError offset (Just (Tokens tokenStream)) expected) =
+formatError (TrivialError offset unexpected expected) =
-  "Parse error at offset " ++ show offset ++ ": unexpected token "
+  let unexpectedMsg = case unexpected of
-    ++ show tokenStream ++ ", expected one of " ++ show (Set.toList expected)
+        Just x  -> "unexpected token " ++ show x
-showError (FancyError offset fancy) =
+        Nothing -> "unexpected end of input"
-  "Parse error at offset " ++ show offset ++ ":\n " ++ unlines (map show (Set.toList fancy))
+      expectedMsg = if null expected
-showError (TrivialError offset Nothing expected) =
+        then ""
-  "Parse error at offset " ++ show offset ++ ": expected one of "
+        else "expected " ++ show (Set.toList 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

@@ -1,25 +1,68 @@
 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
+      if
-      let newEnv   = evalSingle clearEnv (parseSingle input)
+        | Nothing <- minput                     -> outputStrLn "Exiting tricu"
-      case Map.lookup "__result" newEnv of
+        | Just s  <- minput, strip s == "!exit" -> outputStrLn "Exiting tricu"
-        Just r  -> putStrLn $ "sapling < " ++ show r
+        | Just s  <- minput, strip s == ""      -> do
-        Nothing -> pure ()
+          outputStrLn ""
-      repl newEnv
+          loop env
+        | 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
+  | 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.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)
+
+-- 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
@@ -17,26 +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
-
-_I :: T
-_I = apply (apply _S _K) _K -- Fork (Stem (Stem Leaf)) (Stem Leaf)
-
 -- Booleans
 _false :: T
 _false = Leaf
@@ -48,35 +72,67 @@ _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 +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 ()
+-- 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 +1,411 @@
 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
+  ]
 
 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 tokens = lexTricu "t = x" 
-        case (runParser parseExpression "" input) of
+      case parseSingleExpr tokens 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]
+  ]
-        parseSapling 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)
-        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
-    ]
 
-propertyTests :: TestTree
+lambdaEvalTests :: TestTree
-propertyTests = testGroup "Property Tests"
+lambdaEvalTests = testGroup "Lambda Evaluation Tests"
-    [ testProperty "Lexing and parsing round-trip" $ \input ->
+  [ testCase "Lambda Identity Function" $ do
-        case runParser saplingLexer "" input of
+      let input = "id = (\\x : x)\nid t"
-            Left _ -> property True
+      runTricu input @?= "Leaf"
-            Right tokens -> case runParser parseExpression "" tokens of
+  , testCase "Lambda Constant Function (K combinator)" $ do
-                Left _ -> property True
+      let input = "k = (\\x y : x)\nk t (t t)"
-                Right ast -> parseSingle input === ast
+      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!\""
+  ]

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:        0.7.0
-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 +12,57 @@ 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
+      LambdaCase
-      DeriveGeneric
+      MultiWayIf
-      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
+      LambdaCase
+      MultiWayIf
+      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