Don't require available library to run REPL or decoder

Basic implementation of a module system including tests.

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

@@ -0,0 +1,65 @@
+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: ${{ secrets.REGISTRY_PASSWORD }}
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+
+      - name: Build and shrink binary
+        run: |
+          nix build
+          cp -L ./result/bin/tricu ./tricu
+          chmod 755 ./tricu
+          nix develop --command upx ./tricu
+
+      - name: Release binary
+        uses: akkuman/gitea-release-action@v1
+        with:
+          files: |-
+            ./tricu
+          token: '${{ secrets.RELEASE_TOKEN }}'
+          body: '${{ gitea.event.head_commit.message }}'
+          prerelease: true

README.md

@@ -2,21 +2,23 @@
 
 ## Introduction
 
-tricu (pronounced like "tree-shoe" in English) is a purely functional interpreted language implemented in Haskell. [I'm](https://eversole.co) developing tricu to further research the possibilities offered by the various forms of [Tree Calculi](https://github.com/barry-jay-personal/typed_tree_calculus/blob/main/typed_program_analysis.pdf).
+tricu (pronounced "tree-shoe") is a purely functional interpreted language implemented in Haskell. It is fundamentally based on the application of [Tree Calculus](https://github.com/barry-jay-personal/typed_tree_calculus/blob/main/typed_program_analysis.pdf) terms, but minimal syntax sugar is included to provide a useful programming tool. tricu is under active development and you can expect breaking changes with nearly every commit.
 
-tricu offers minimal syntax sugar yet manages to provide a complete, intuitive, and familiar programming environment. There is great power in simplicity. tricu offers:
+tricu is the word for "tree" in Lojban: `(x1) is a tree of species/cultivar (x2)`.
 
-1. `t` operator behaving by the rules of Tree Calculus
+## Features
-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.
+- Tree Calculus operator: `t`
+- Assignments: `x = t t`
+- Immutable definitions
+- Lambda abstraction syntax: `id = (\a : a)`
+- List, Number, and String literals: `[(2) ("Hello")]` 
+- Function application: `not (not false)`
+- Higher order/first-class functions: `map (\a : lconcat a "!") [("Hello")]`
+- Intensionality blurs the distinction between functions and data (see REPL examples)
+- Simple module system for code organization
 
-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
-
-## What does it look like?
 
 ```
 tricu < -- Anything after `--` on a single line is a comment
@@ -26,19 +28,24 @@ 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 < -- Intensionality! We can inspect the structure of a function or data.
 tricu < triage = (\a b c : t (t a b) c)
 tricu < test = triage "Leaf" (\z : "Stem") (\a b : "Fork")
-tricu < test t t
+tricu < test (t t)
 tricu > "Stem"
-tricu < -- We can even write a function to convert a function to source code
+tricu < -- We can even convert a term back to source code (/demos/toSource.tri)
-tricu < toTString id
+tricu < toSource not?
-tricu > "t (t (t t)) t"
+tricu > "(t (t (t t) (t t t)) (t t (t t t)))"
+tricu < -- or calculate its size (/demos/size.tri)
+tricu < size not?
+tricu > 12
 ```
 
 ## Installation and Use
 
-You can easily build and/or run this project using [Nix](https://nixos.org/download/).
+[Releases are available for Linux.](https://git.eversole.co/James/tricu/releases)
+
+Or you can easily build and run this project using [Nix](https://nixos.org/download/).
 
 - Quick Start (REPL): 
   - `nix run git+https://git.eversole.co/James/tricu`
@@ -65,7 +72,7 @@ tricu eval [OPTIONS]
 
   -f --file=FILE  Input file path(s) for evaluation.
                     Defaults to stdin.
-  -t --form=FORM  Optional output form: (tree|fsl|ast|ternary|ascii).
+  -t --form=FORM  Optional output form: (tree|fsl|ast|ternary|ascii|decode).
                     Defaults to tricu-compatible `t` tree form.
 
 tricu decode [OPTIONS]
@@ -79,4 +86,4 @@ tricu decode [OPTIONS]
 
 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 tricu 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/LevelOrderTraversal.tri

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

demos/equality.tri

@@ -0,0 +1,41 @@
+!module Equality
+
+!import "lib/base.tri" Lib
+
+main = lambdaEqualsTC
+
+-- We represent `false` with a Leaf and `true` with a Stem Leaf
+demo_false = t
+demo_true  = t t
+
+-- Tree Calculus representation of the Boolean `not` function
+not_TC?     = t (t (t t) (t t t)) (t t (t t t))
+
+-- /demos/toSource.tri contains an explanation of `triage`
+demo_triage = \a b c : t (t a b) c
+demo_matchBool = (\ot of : demo_triage
+  of
+  (\_ : ot)
+  (\_ _ : ot)
+)
+-- Lambda representation of the Boolean `not` function
+not_Lambda? = demo_matchBool demo_false demo_true
+
+-- Since tricu eliminates Lambda terms to SKI combinators, the tree form of many
+-- functions defined via Lambda terms are larger than the most efficient TC
+-- representation. Between different languages that evaluate to tree calculus 
+-- terms, the exact implementation of Lambda elimination may differ and lead 
+-- to different tree representations even if they share extensional behavior.
+
+-- Let's see if these are the same:
+lambdaEqualsTC = Lib.equal? not_TC? not_Lambda?
+
+-- Here are some checks to verify their extensional behavior is the same:
+true_TC?  = not_TC? demo_false
+false_TC? = not_TC? demo_true
+
+true_Lambda?  = not_Lambda? demo_false
+false_Lambda? = not_Lambda? demo_true
+
+bothTrueEqual?  = Lib.equal? true_TC?  true_Lambda?
+bothFalseEqual? = Lib.equal? false_TC? false_Lambda?

demos/levelOrderTraversal.tri

@@ -0,0 +1,65 @@
+!module LOT
+
+!import "lib/base.tri" Lib
+
+main = exampleTwo
+-- Level Order Traversal of a labelled binary tree
+-- Objective: Print each "level" of the tree on a separate line
+--
+-- We model labelled binary trees as nested lists where values act as labels. We
+-- require explicit notation of empty nodes. Empty nodes can be represented
+-- with an empty list, `[]`, which evaluates 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 : Lib.head node
+
+left = (\node : Lib.if (Lib.emptyList? node)
+  [] 
+  (Lib.if (Lib.emptyList? (Lib.tail node)) 
+    [] 
+    (Lib.head (Lib.tail node))))
+
+right = (\node : Lib.if (Lib.emptyList? node) 
+  [] 
+  (Lib.if (Lib.emptyList? (Lib.tail node)) 
+    [] 
+    (Lib.if (Lib.emptyList? (Lib.tail (Lib.tail node))) 
+      [] 
+      (Lib.head (Lib.tail (Lib.tail node))))))
+
+processLevel = Lib.y (\self queue : Lib.if (Lib.emptyList? queue) 
+  [] 
+  (Lib.pair (Lib.map label queue) (self (Lib.filter 
+    (\node : Lib.not? (Lib.emptyList? node)) 
+      (Lib.lconcat (Lib.map left queue) (Lib.map right queue))))))
+
+levelOrderTraversal_ = \a : processLevel (t a t)
+
+toLineString = Lib.y (\self levels : Lib.if (Lib.emptyList? levels) 
+  "" 
+  (Lib.lconcat 
+    (Lib.lconcat (Lib.map (\x : Lib.lconcat x " ") (Lib.head levels)) "") 
+    (Lib.if (Lib.emptyList? (Lib.tail levels)) "" (Lib.lconcat (t (t 10 t) t) (self (Lib.tail levels))))))
+
+levelOrderToString = \s : toLineString (levelOrderTraversal_ s)
+
+flatten = Lib.foldl (\acc x : Lib.lconcat acc x) ""
+
+levelOrderTraversal = \s : Lib.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]]]

demos/size.tri

@@ -0,0 +1,25 @@
+!module Size
+
+!import "lib/base.tri" Lib
+
+main = size size
+
+compose = \f g x : f (g x)
+
+succ = Lib.y (\self :
+  Lib.triage
+    1
+    t
+    (Lib.triage
+      (t (t t))
+      (\_ Lib.tail : t t (self Lib.tail))
+      t))
+
+size = (\x :
+  (Lib.y (\self x :
+    compose succ
+      (Lib.triage
+        (\x : x)
+        self
+        (\x y : compose (self x) (self y))
+        x)) x 0))

demos/toSource.tri

@@ -0,0 +1,51 @@
+!module ToSource
+
+!import "lib/base.tri" Lib
+
+main = toSource Lib.not?
+-- 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 = (\leaf stem fork : t (t leaf stem) fork)
+
+-- Base case of a single Leaf
+sourceLeaf = t (Lib.head "t")
+
+-- Stem case
+sourceStem = (\convert : (\a rest :
+  t (Lib.head "(")                       -- Start with a left parenthesis "(".
+    (t (Lib.head "t")                    -- Add a "t"
+      (t (Lib.head " ")                  -- Add a space.
+        (convert a                       -- Recursively convert the argument.
+          (t (Lib.head ")") rest))))))   -- Close with ")" and append the rest.
+
+-- Fork case
+sourceFork = (\convert : (\a b rest :
+  t (Lib.head "(")                           -- Start with a left parenthesis "(".
+    (t (Lib.head "t")                        -- Add a "t"
+      (t (Lib.head " ")                      -- Add a space.
+        (convert a                           -- Recursively convert the first arg.
+          (t (Lib.head " ")                  -- Add another space.
+            (convert b                       -- Recursively convert the second arg.
+              (t (Lib.head ")") rest)))))))) -- Close with ")" and append the rest.
+
+-- Wrapper around triage 
+toSource_ = Lib.y (\self arg :
+  Lib.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 Lib.true -- OUT: "(t t)"
+exampleTwo = toSource Lib.not? -- OUT: "(t (t (t t) (t t t)) (t t (t t t)))"

flake.nix

@@ -32,10 +32,11 @@
         defaultPackage = self.packages.${system}.default;
 
         devShells.default = pkgs.mkShell {
-          buildInputs = with pkgs.haskellPackages; [
+          buildInputs = with pkgs; [
-            cabal-install
+            haskellPackages.cabal-install
-            ghcid
+            haskellPackages.ghcid
             customGHC
+            upx
           ];
           inputsFrom = builtins.attrValues self.packages.${system};
         };

lib/base.tri

@@ -7,35 +7,77 @@ 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    = \a : a
-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))
+if    = \cond then else : t (t else (t t then)) t cond
-matchList = (\oe oc : triage oe _ oc)
+
-matchPair = (\op : triage _ _ op)
+y = ((\mut wait fun : wait mut (\x : fun (wait mut x)))
-not = matchBool false true
+     (\x : x x)
-and = matchBool id (\z : false)
+     (\a0 a1 a2 : t (t a0) (t t a2) a1))
-if = (\cond then else : t (t else (t t then)) t cond)
+
-test = triage "Leaf" (\z : "Stem") (\a b : "Fork")
+triage = \leaf stem fork : t (t leaf stem) fork
-emptyList = matchList true (\y z : false)
+test   = triage "Leaf" (\_ : "Stem") (\_ _ : "Fork")
-head = matchList t (\hd tl : hd)
+
-tail = matchList t (\hd tl : tl)
+matchBool = (\ot of : triage
-lconcat = y (\self : matchList (\k : k) (\h r k : pair h (self r k)))
+  of
-lAnd = triage (\x : false) (\_ x : x) (\_ _ x : x)
+  (\_ : ot)
-lOr = triage (\x : x) (\_ _ : true) (\_ _ x : true)
+  (\_ _ : ot)
-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))))
+matchList = \a b : triage a _ b
-hfilter = y (\self : matchList (\f : t) (\hd tl f : matchBool (t hd) i (f hd) (self tl f)))
+
-filter = (\f l : hfilter l f)
+matchPair = \a   : triage _ _ a
-hfoldl = y (\self f l x : matchList (\acc : acc) (\hd tl acc : self f tl (f acc hd)) l x)
+
-foldl  = (\f x l : hfoldl f l x)
+not? = matchBool false true
-hfoldr = y (\self x f l : matchList x (\hd tl : f (self x f tl) hd) l)
+and? = matchBool id (\_ : false)
-foldr  = (\f x l : hfoldr x f l)
+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

src/Eval.hs

@@ -3,115 +3,189 @@ module Eval where
 import Parser
 import Research
 
+import Data.List (partition, (\\))
 import Data.Map  (Map)
-
 import qualified Data.Map as Map
 import qualified Data.Set as Set
 
-evalSingle :: Map String T -> TricuAST -> Map String T
+evalSingle :: Env -> TricuAST -> Env
-evalSingle env term = case term of
+evalSingle env term
-  SFunc name [] body ->
+  | SDef name [] body <- term
-    let lineNoLambda = eliminateLambda body
+  = case Map.lookup name env of
-        result = evalAST env lineNoLambda
+      Just existingValue
-    in Map.insert "__result" result (Map.insert name result env)
+        | existingValue == evalAST env body -> env
-  SLambda _ body ->
+        | otherwise -> errorWithoutStackTrace $
-    let result = evalAST env body
+            "Unable to rebind immutable identifier: '" ++ name
-    in Map.insert "__result" result env
+      Nothing ->
-  SApp func arg ->
+        let res = evalAST env body
-    let result = apply (evalAST env $ eliminateLambda func) (evalAST env $ eliminateLambda arg)
+        in Map.insert "!result" res (Map.insert name res env)
-    in Map.insert "__result" result env
+  | SApp func arg <- term 
-  SVar name ->
+  = let res = apply (evalAST env func) (evalAST env arg)
-    case Map.lookup name env of
+      in Map.insert "!result" res env
-      Just value -> Map.insert "__result" value env
+  | SVar name <- term 
-      Nothing -> errorWithoutStackTrace $ "Variable " ++ name ++ " not defined"
+  = case Map.lookup name env of
-  _ ->
+        Just v  -> Map.insert "!result" v env
-    let result = evalAST env term
+        Nothing ->
-    in Map.insert "__result" result env
+          errorWithoutStackTrace $ "Variable `" ++ name ++ "` not defined\n\
+          \This error should never occur here. Please report this as an issue."
+  | otherwise 
+  = Map.insert "!result" (evalAST env term) env
 
-evalTricu :: Map String T -> [TricuAST] -> Map String T
+evalTricu :: Env -> [TricuAST] -> Env
-evalTricu env list = evalTricu' env (filter (/= SEmpty) list)
+evalTricu env x = go env (reorderDefs env x)
   where
-  evalTricu' :: Map String T -> [TricuAST] -> Map String T
+    go env []     = env
-  evalTricu' env [] = env
+    go env [x]    =
-  evalTricu' env [lastLine] =
+      let updatedEnv = evalSingle env x
-    let lastLineNoLambda = eliminateLambda lastLine
+      in Map.insert "!result" (result updatedEnv) updatedEnv
-        updatedEnv = evalSingle env lastLineNoLambda
+    go env (x:xs) =
-    in Map.insert "__result" (result updatedEnv) updatedEnv
+      evalTricu (evalSingle env x) xs
-  evalTricu' env (line:rest) =
-    let lineNoLambda = eliminateLambda line
-        updatedEnv = evalSingle env lineNoLambda
-    in evalTricu updatedEnv rest
 
-evalAST :: Map String T -> TricuAST -> T
+evalAST :: Env -> TricuAST -> T
-evalAST env term = case term of
+evalAST env term
-  SVar name -> case Map.lookup name env of
+  | SLambda _ _ <- term = evalAST env (elimLambda term)
-    Just value -> value
+  | SVar   name <- term = evalVar name
-    Nothing -> errorWithoutStackTrace $ "Variable " ++ name ++ " not defined"
+  | TLeaf       <- term = Leaf
-  TLeaf -> Leaf
+  | TStem  t    <- term = Stem (evalAST env t)
-  TStem t -> Stem (evalAST env t)
+  | TFork  t u  <- term = Fork (evalAST env t) (evalAST env u)
-  TFork t1 t2 -> Fork (evalAST env t1) (evalAST env t2)
+  | SApp   t u  <- term = apply (evalAST env t) (evalAST env u)
-  SApp t1 t2 -> apply (evalAST env t1) (evalAST env t2)
+  | SStr   s    <- term = ofString s
-  SStr str -> ofString str
+  | SInt   n    <- term = ofNumber n
-  SInt num -> ofNumber num
+  | SList  xs   <- term = ofList (map (evalAST env) xs)
-  SList elems -> ofList (map (evalAST env) elems)
+  | SEmpty      <- term = Leaf
-  SEmpty -> Leaf
+  | otherwise           = errorWithoutStackTrace "Unexpected AST term"
-  SFunc name args body ->
+    where
-    errorWithoutStackTrace $ "Unexpected function definition " ++ name
+      evalVar name = Map.findWithDefault
-  SLambda {} -> errorWithoutStackTrace "Internal error: SLambda found in evalAST after elimination."
+        (errorWithoutStackTrace $ "Variable " ++ name ++ " not defined")
+        name env
 
-eliminateLambda :: TricuAST -> TricuAST
+elimLambda :: TricuAST -> TricuAST
-eliminateLambda (SLambda (v:vs) body)
+elimLambda = go
-  | null vs = lambdaToT v (eliminateLambda body)
+  where
-  | otherwise = eliminateLambda (SLambda [v] (SLambda vs body))
+    -- η-reduction
-eliminateLambda (SApp f arg) = SApp (eliminateLambda f) (eliminateLambda arg)
+    go (SLambda [v] (SApp f (SVar x)))
-eliminateLambda (TStem t) = TStem (eliminateLambda t)
+      | v == x && not (isFree v f) = elimLambda f
-eliminateLambda (TFork l r) = TFork (eliminateLambda l) (eliminateLambda r)
+    -- Triage optimization
-eliminateLambda (SList xs) = SList (map eliminateLambda xs)
+    go (SLambda [a] (SLambda [b] (SLambda [c] body)))
-eliminateLambda other = other
+      | body == triageBody         = _TRIAGE
+      where
+        triageBody =
+          (SApp (SApp TLeaf (SApp (SApp TLeaf (SVar a)) (SVar b))) (SVar c))
+    -- Composition optimization
+    go (SLambda [f] (SLambda [g] (SLambda [x] body)))
+      | body == composeBody        = _COMPOSE
+      where
+        composeBody = SApp (SVar f) (SApp (SVar g) (SVar x))
+    -- General elimination
+    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
 
--- https://github.com/barry-jay-personal/typed_tree_calculus/blob/main/typed_program_analysis.pdf
+    toSKI x (SVar y)
--- Chapter 4: Lambda-Abstraction
+      | x == y           = _I
-lambdaToT :: String -> TricuAST -> TricuAST
+      | otherwise        = SApp _K (SVar y)
-lambdaToT x (SVar y)
+    toSKI x t@(SApp n u)
-  | x == y = tI
+      | not (isFree x t) = SApp _K t
-lambdaToT x (SVar y)
+      | otherwise        = SApp (SApp _S (toSKI x n)) (toSKI x u)
-  | x /= y = SApp tK (SVar y)
+    toSKI x t
-lambdaToT x t
+      | not (isFree x t) = SApp _K t
-  | not (isFree x t) = SApp tK t
+      | otherwise        = errorWithoutStackTrace "Unhandled toSKI conversion"
-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
 
-freeVars :: TricuAST -> Set.Set String
+    _S       = parseSingle "t (t (t t t)) t"
-freeVars (SVar v) = Set.singleton v
+    _K       = parseSingle "t t"
-freeVars (SInt _) = Set.empty
+    _I       = parseSingle "t (t (t t)) t"
-freeVars (SStr _) = Set.empty
+    _TRIAGE  = parseSingle "t (t (t t (t (t (t t t))))) t"
-freeVars (SList xs) = foldMap freeVars xs
+    _COMPOSE = parseSingle "t (t (t t (t (t (t t t)) t))) (t t)"
-freeVars (SApp f arg) = freeVars f <> freeVars arg
-freeVars TLeaf = Set.empty
-freeVars (SFunc _ _ b) = freeVars b
-freeVars (TStem t) = freeVars t
-freeVars (TFork l r) = freeVars l <> freeVars r
-freeVars (SLambda vs b) = foldr Set.delete (freeVars b) vs
 
 isFree :: String -> TricuAST -> Bool
 isFree x = Set.member x . freeVars
 
--- We need the SKI operators in an unevaluated TricuAST tree form so that we
+freeVars :: TricuAST -> Set.Set String
--- can keep the evaluation functions straightforward
+freeVars (SVar    v    ) = Set.singleton v
-tI :: TricuAST
+freeVars (SInt    _    ) = Set.empty
-tI = SApp (SApp TLeaf (SApp TLeaf (SApp TLeaf TLeaf))) TLeaf
+freeVars (SStr    _    ) = Set.empty
+freeVars (SList   s    ) = foldMap freeVars s
+freeVars (SApp    f a  ) = freeVars f <> freeVars a
+freeVars (TLeaf        ) = Set.empty
+freeVars (SDef   _ _ 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
+freeVars _               = Set.empty
 
-tK :: TricuAST
+reorderDefs :: Env -> [TricuAST] -> [TricuAST]
-tK = SApp TLeaf TLeaf
+reorderDefs env defs
+  | not (null missingDeps) =
+      errorWithoutStackTrace $
+        "Missing dependencies detected: " ++ show missingDeps
+  | otherwise = orderedDefs ++ others
+  where
+    (defsOnly, others) = partition isDef defs
+    defNames = [ name | SDef name _ _ <- defsOnly ]
 
-tS :: TricuAST
+    defsWithFreeVars = [(def, freeVars body) | def@(SDef _ _ body) <- defsOnly]
-tS = SApp (SApp TLeaf (SApp TLeaf (SApp (SApp TLeaf TLeaf) TLeaf))) TLeaf
 
-result :: Map String T -> T
+    graph = buildDepGraph defsOnly
-result r = case Map.lookup "__result" r of
+    sortedDefs = sortDeps graph
+    defMap = Map.fromList [(name, def) | def@(SDef name _ _) <- defsOnly]
+    orderedDefs = map (\name -> defMap Map.! name) sortedDefs
+
+    freeVarsDefs = foldMap snd defsWithFreeVars
+    freeVarsOthers = foldMap freeVars others
+    allFreeVars = freeVarsDefs <> freeVarsOthers
+    validNames = Set.fromList defNames `Set.union` Set.fromList (Map.keys env)
+    missingDeps = Set.toList (allFreeVars `Set.difference` validNames)
+
+    isDef (SDef _ _ _) = True
+    isDef _            = False
+
+buildDepGraph :: [TricuAST] -> Map.Map String (Set.Set String)
+buildDepGraph topDefs
+  | not (null duplicateNames) =
+      errorWithoutStackTrace $
+        "Duplicate definitions detected: " ++ show duplicateNames
+  | otherwise =
+      Map.fromList
+        [ (name, depends topDefs (SDef name [] body))
+        | SDef name _ body <- topDefs]
+  where
+    names = [name | SDef name _ _ <- topDefs]
+    duplicateNames =
+      [ name | (name, count) <- Map.toList (countOccurrences names) , count > 1]
+    countOccurrences = foldr (\x -> Map.insertWith (+) x 1) Map.empty
+
+sortDeps :: Map.Map String (Set.Set String) -> [String]
+sortDeps graph = go [] Set.empty (Map.keys graph)
+  where
+    go sorted sortedSet [] = sorted
+    go sorted sortedSet remaining =
+      let ready = [ name | name <- remaining
+                        , let deps = Map.findWithDefault Set.empty name graph
+                        , Set.isSubsetOf deps sortedSet ]
+          notReady = remaining \\ ready
+      in if null ready
+         then errorWithoutStackTrace
+          "ERROR: Cyclic dependency detected and prohibited.\n\
+          \RESOLVE: Use nested lambdas."
+         else go (sorted ++ ready)
+                 (Set.union sortedSet (Set.fromList ready))
+                 notReady
+
+depends :: [TricuAST] -> TricuAST -> Set.Set String
+depends topDefs (SDef _ _ body) =
+  Set.intersection
+    (Set.fromList [n | SDef n _ _ <- topDefs])
+    (freeVars body)
+depends _ _ = Set.empty
+
+result :: Env -> T
+result r = case Map.lookup "!result" r of
   Just a -> a
-  Nothing -> errorWithoutStackTrace "No __result field found in provided environment"
+  Nothing -> errorWithoutStackTrace "No !result field found in provided env"
+
+mainResult :: Env -> T
+mainResult r = case Map.lookup "main" r of
+  Just  a -> a
+  Nothing -> errorWithoutStackTrace "No valid definition for `main` found."

src/FileEval.hs

@@ -1,30 +1,150 @@
 module FileEval where
 
 import Eval
+import Lexer
 import Parser
 import Research
 
+import Data.List       (partition)
+import Control.Monad   (foldM)
 import System.IO
 
 import qualified Data.Map as Map
+import qualified Data.Set as Set
 
 evaluateFileResult :: FilePath -> IO T
 evaluateFileResult filePath = do
   contents <- readFile filePath
-  let asts = parseTricu contents
+  let tokens = lexTricu contents
-  let finalEnv = evalTricu Map.empty asts
+  let moduleName = case parseProgram tokens of
-  case Map.lookup "__result" finalEnv of
+        Right ((SModule name) : _) -> name
+        _                          -> ""
+  case parseProgram tokens of
+    Left err -> errorWithoutStackTrace (handleParseError err)
+    Right _ -> do
+      ast <- preprocessFile filePath
+      let finalEnv = mainAlias moduleName $ evalTricu Map.empty ast
+      case Map.lookup "main" finalEnv of
         Just finalResult -> return finalResult
-    Nothing -> errorWithoutStackTrace "No expressions to evaluate found"
+        Nothing -> errorWithoutStackTrace "No `main` function detected"
 
 evaluateFile :: FilePath -> IO Env
 evaluateFile filePath = do
   contents <- readFile filePath
-  let asts = parseTricu contents
+  let tokens = lexTricu contents
-  pure $ evalTricu Map.empty asts
+  let moduleName = case parseProgram tokens of
+        Right ((SModule name) : _) -> name
+        _                          -> ""
+  case parseProgram tokens of
+    Left err -> errorWithoutStackTrace (handleParseError err)
+    Right _ -> do
+      ast <- preprocessFile filePath
+      pure $ mainAlias moduleName $ evalTricu Map.empty ast
 
 evaluateFileWithContext :: Env -> FilePath -> IO Env
 evaluateFileWithContext env filePath = do
   contents <- readFile filePath
-  let asts = parseTricu contents
+  let tokens = lexTricu contents
-  pure $ evalTricu env asts
+  let moduleName = case parseProgram tokens of
+        Right ((SModule name) : _) -> name
+        _                          -> ""
+  case parseProgram tokens of
+    Left err -> errorWithoutStackTrace (handleParseError err)
+    Right _ -> do
+      ast <- preprocessFile filePath
+      pure $ mainAlias moduleName $ evalTricu env ast
+
+mainAlias :: String -> Env -> Env
+mainAlias "" env = env
+mainAlias moduleName env =
+  case Map.lookup (moduleName ++ ".main") env of
+    Just value -> Map.insert "main" value env
+    Nothing    -> env
+
+preprocessFile :: FilePath -> IO [TricuAST]
+preprocessFile filePath = preprocessFile' Set.empty filePath
+
+preprocessFile' :: Set.Set FilePath -> FilePath -> IO [TricuAST]
+preprocessFile' inProgress filePath
+  | filePath `Set.member` inProgress = 
+      errorWithoutStackTrace $ "Encountered cyclic import: " ++ filePath
+  | otherwise = do
+      contents <- readFile filePath
+      let tokens = lexTricu contents
+      case parseProgram tokens of
+        Left err -> errorWithoutStackTrace (handleParseError err)
+        Right asts -> do
+          let (moduleName, restAST) = extractModule asts
+          let (imports, nonImports) = partition isImport restAST
+          let newInProgress = Set.insert filePath inProgress
+          importedASTs <- concat <$> mapM (processImport newInProgress) imports
+          let namespacedAST = namespaceDefinitions moduleName nonImports
+          pure $ importedASTs ++ namespacedAST
+  where
+    extractModule :: [TricuAST] -> (String, [TricuAST])
+    extractModule ((SModule name) : xs) = (name, xs)
+    extractModule xs                    = ("", xs)
+
+    isImport :: TricuAST -> Bool
+    isImport (SImport _ _) = True
+    isImport _             = False
+
+    processImport :: Set.Set FilePath -> TricuAST -> IO [TricuAST]
+    processImport inProgress (SImport filePath moduleName) = do
+      importedAST <- preprocessFile' inProgress filePath
+      pure $ namespaceDefinitions moduleName importedAST
+    processImport _ _ = error "Unexpected non-import in processImport"
+
+namespaceDefinitions :: String -> [TricuAST] -> [TricuAST]
+namespaceDefinitions moduleName = map (namespaceDefinition moduleName)
+
+namespaceDefinition :: String -> TricuAST -> TricuAST
+namespaceDefinition "" def = def
+namespaceDefinition moduleName (SDef name args body)
+  | isPrefixed name = SDef name args (namespaceBody moduleName body)
+  | otherwise = SDef (namespaceVariable moduleName name) 
+                        args (namespaceBody moduleName body)
+namespaceDefinition moduleName other =
+  namespaceBody moduleName other
+
+namespaceBody :: String -> TricuAST -> TricuAST
+namespaceBody moduleName (SVar name)
+  | isPrefixed name = SVar name
+  | otherwise = SVar (namespaceVariable moduleName name)
+namespaceBody moduleName (SApp func arg) =
+  SApp (namespaceBody moduleName func) (namespaceBody moduleName arg)
+namespaceBody moduleName (SLambda args body) =
+  SLambda args (namespaceBodyScoped moduleName args body)
+namespaceBody moduleName (SList items) =
+  SList (map (namespaceBody moduleName) items)
+namespaceBody moduleName (TFork left right) =
+  TFork (namespaceBody moduleName left) (namespaceBody moduleName right)
+namespaceBody moduleName (TStem subtree) =
+  TStem (namespaceBody moduleName subtree)
+namespaceBody moduleName (SDef name args body)
+  | isPrefixed name = SDef name args (namespaceBody moduleName body)
+  | otherwise = SDef (namespaceVariable moduleName name) 
+                        args (namespaceBody moduleName body)
+namespaceBody _ other = other
+
+namespaceBodyScoped :: String -> [String] -> TricuAST -> TricuAST
+namespaceBodyScoped moduleName args body = case body of
+  SVar name ->
+    if name `elem` args
+      then SVar name
+      else namespaceBody moduleName (SVar name)
+  SApp func arg -> SApp (namespaceBodyScoped moduleName args func) (namespaceBodyScoped moduleName args arg)
+  SLambda innerArgs innerBody -> SLambda innerArgs (namespaceBodyScoped moduleName (args ++ innerArgs) innerBody)
+  SList items -> SList (map (namespaceBodyScoped moduleName args) items)
+  TFork left right -> TFork (namespaceBodyScoped moduleName args left) (namespaceBodyScoped moduleName args right)
+  TStem subtree -> TStem (namespaceBodyScoped moduleName args subtree)
+  SDef name innerArgs innerBody ->
+    SDef (namespaceVariable moduleName name) innerArgs (namespaceBodyScoped moduleName (args ++ innerArgs) innerBody)
+  other -> other
+
+isPrefixed :: String -> Bool
+isPrefixed name = '.' `elem` name
+
+namespaceVariable :: String -> String -> String
+namespaceVariable "" name = name
+namespaceVariable moduleName name = moduleName ++ "." ++ name

src/Lexer.hs

@@ -18,10 +18,13 @@ keywordT = string "t" *> notFollowedBy alphaNumChar *> pure LKeywordT
 identifier :: Lexer LToken
 identifier = do
   first <- letterChar <|> char '_'
-  rest <- many (letterChar <|> char '_' <|> char '-' <|> digitChar)
+  rest  <- many $ letterChar 
+              <|> digitChar 
+              <|> char '_' <|> char '-' <|> char '?' <|> char '.'
+              <|> char '$' <|> char '#' <|> char '@' <|> char '%'
   let name = first : rest
-  if (name == "t" || name == "__result")
+  if (name == "t" || name == "!result")
-    then fail "Keywords (`t`, `__result`) cannot be used as an identifier"
+    then fail "Keywords (`t`, `!result`) cannot be used as an identifier"
     else return (LIdentifier name)
 
 integerLiteral :: Lexer LToken
@@ -36,6 +39,22 @@ stringLiteral = do
   char '"' --"
   return (LStringLiteral content)
 
+lModule :: Lexer LToken
+lModule = do
+  _ <- string "!module"
+  space1
+  LIdentifier moduleName <- identifier
+  return (LModule moduleName)
+
+lImport :: Lexer LToken
+lImport = do
+  _ <- string "!import"
+  space1
+  LStringLiteral path <- stringLiteral
+  space1
+  LIdentifier name <- identifier
+  return (LImport path name)
+
 assign :: Lexer LToken
 assign = char '=' *> pure LAssign
 
@@ -61,21 +80,33 @@ lnewline :: Lexer LToken
 lnewline = char '\n' *> pure LNewline
 
 sc :: Lexer ()
-sc = space space1 (skipLineComment "--") (skipBlockComment "|-" "-|")
+sc = space
+  (void $ takeWhile1P (Just "space") (\c -> c == ' ' || c == '\t'))
+  (skipLineComment "--")
+  (skipBlockComment "|-" "-|")
 
 tricuLexer :: Lexer [LToken]
 tricuLexer = do
   sc
+  header <- many $ do
+    tok <- choice
+      [ try lModule
+      , try lImport
+      , lnewline
+      ]
+    sc
+    pure tok
   tokens <- many $ do
     tok <- choice tricuLexer'
     sc
     pure tok
   sc
   eof
-  pure tokens
+  pure (header ++ tokens)
   where
     tricuLexer' =
-        [ try identifier
+      [ try lnewline
+      , try identifier
       , try keywordT
       , try integerLiteral
       , try stringLiteral

src/Main.hs

@@ -1,6 +1,6 @@
 module Main where
 
-import Eval                   (evalTricu, result)
+import Eval                   (evalTricu, mainResult, result)
 import FileEval
 import Parser                 (parseTricu)
 import REPL
@@ -16,7 +16,7 @@ import qualified Data.Map as Map
 data TricuArgs
   = Repl
   | Evaluate { file :: [FilePath], form :: EvaluatedForm }
-  | Decode { file :: [FilePath] }
+  | TDecode { file :: [FilePath] }
   deriving (Show, Data, Typeable)
 
 replMode :: TricuArgs
@@ -31,7 +31,7 @@ evaluateMode = Evaluate
       \ Defaults to stdin."
       &= name "f" &= typ "FILE"
     , form = TreeCalculus &= typ "FORM"
-      &= help "Optional output form: (tree|fsl|ast|ternary|ascii).\n \
+      &= help "Optional output form: (tree|fsl|ast|ternary|ascii|decode).\n \
       \ Defaults to tricu-compatible `t` tree form."
       &= name "t"
   }
@@ -40,7 +40,7 @@ evaluateMode = Evaluate
   &= name "eval"
 
 decodeMode :: TricuArgs
-decodeMode = Decode
+decodeMode = TDecode
   { file = def
     &= help "Optional input file path to attempt decoding.\n \
     \ Defaults to stdin."
@@ -60,8 +60,7 @@ main = do
     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.empty
-      repl $ Map.delete "__result" library
     Evaluate { file = filePaths, form = form } -> do
       result <- case filePaths of
         [] -> do
@@ -70,15 +69,17 @@ main = do
         (filePath:restFilePaths) -> do
             initialEnv <- evaluateFile filePath
             finalEnv <- foldM evaluateFileWithContext initialEnv restFilePaths
-            pure $ result finalEnv
+            pure $ mainResult finalEnv
       let fRes = formatResult form result
       putStr fRes
-    Decode { file = filePaths } -> do
+    TDecode { file = filePaths } -> do
       value <- case filePaths of
         [] -> getContents
         (filePath:_) -> readFile filePath
-      library <- liftIO $ evaluateFile "./lib/base.tri"
+      putStrLn $ decodeResult $ result $ evalTricu Map.empty $ parseTricu value
-      putStrLn $ decodeResult $ result $ evalTricu library $ parseTricu value
 
 runTricu :: String -> T
-runTricu = result . evalTricu Map.empty . parseTricu
+runTricu input =
+  let asts     = parseTricu input
+      finalEnv = evalTricu Map.empty asts
+   in result finalEnv

src/Parser.hs

@@ -1,277 +1,316 @@
 module Parser where
 
 import Lexer
-import Research hiding       (toList)
+import Research
 
+import Control.Monad (void)
+import Control.Monad.State
 import Data.List.NonEmpty (toList)
 import Data.Void (Void)
 import Text.Megaparsec
-import Text.Megaparsec.Char
 import Text.Megaparsec.Error (ParseErrorBundle, errorBundlePretty)
-
 import qualified Data.Set as Set
 
-type Parser    = Parsec Void [LToken]
+data PState = PState
-type AltParser = Parsec Void String
+  { parenDepth  :: Int
+  , bracketDepth :: Int
+  } deriving (Show)
+
+type ParserM = StateT PState (Parsec Void [LToken])
+
+satisfyM :: (LToken -> Bool) -> ParserM LToken
+satisfyM f = do
+  token <- lift (satisfy f)
+  modify' (updateDepth token)
+  return token
+
+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
+
+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)"
+
+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
+parseTricu input =
-  | null tokens = []
+  case lexTricu input of
-  | otherwise = map parseSingle tokens
-  where
-    tokens = case lexTricu input of
     [] -> []
-      tokens -> lines input
+    toks ->
+      case parseProgram toks of
+        Left err   -> errorWithoutStackTrace (handleParseError err)
+        Right asts -> asts
 
 parseSingle :: String -> TricuAST
-parseSingle input = case lexTricu input of
+parseSingle input =
+  case lexTricu input of
     [] -> SEmpty
-  tokens -> case runParser parseExpression "" tokens of
+    toks ->
-    Left err -> error $ handleParseError err
+      case parseSingleExpr toks of
+        Left err -> errorWithoutStackTrace (handleParseError err)
         Right ast -> ast
 
-parseExpression :: Parser TricuAST
+parseProgramM :: ParserM [TricuAST]
-parseExpression = choice
+parseProgramM = do
-  [ try parseFunction
+  skipMany topLevelNewline
-  , try parseLambda
+  moduleNode <- optional parseModuleM
-  , try parseLambdaExpression
+  skipMany topLevelNewline
-  , try parseListLiteral
+  importNodes <- many (do
-  , try parseApplication
+    node <- parseImportM
-  , try parseTreeTerm
+    skipMany topLevelNewline
-  , parseLiteral
+    return node)
+  skipMany topLevelNewline
+  exprs <- sepEndBy parseOneExpression (some topLevelNewline)
+  skipMany topLevelNewline
+  return (maybe [] (: []) moduleNode ++ importNodes ++ exprs)
+
+
+parseModuleM :: ParserM TricuAST
+parseModuleM = do
+  LModule moduleName <- satisfyM isModule
+  pure (SModule moduleName)
+  where
+    isModule (LModule _) = True
+    isModule _           = False
+
+parseImportM :: ParserM TricuAST
+parseImportM = do
+  LImport filePath moduleName <- satisfyM isImport
+  pure (SImport filePath moduleName)
+  where
+    isImport (LImport _ _) = True
+    isImport _             = False
+
+parseOneExpression :: ParserM TricuAST
+parseOneExpression = scnParserM *> parseExpressionM
+
+scnParserM :: ParserM ()
+scnParserM = skipMany $ do
+  t  <- lookAhead anySingle
+  st <- get
+  if | (parenDepth st > 0 || bracketDepth st > 0) && (t == LNewline) ->
+       void $ satisfyM (== LNewline)
+     | 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
   ]
 
-scnParser :: Parser ()
+parseFunctionM :: ParserM TricuAST
-scnParser = skipMany (satisfy isNewline)
+parseFunctionM = do
+  let ident = (\case LIdentifier _ -> True; _ -> False)
+  LIdentifier name <- satisfyM ident
+  args <- many $ satisfyM ident
+  _    <- satisfyM (== LAssign)
+  scnParserM
+  body <- parseExpressionM
+  pure (SDef name (map getIdentifier args) body)
 
-parseFunction :: Parser TricuAST
+parseLambdaM :: ParserM TricuAST
-parseFunction = do
+parseLambdaM = do
-  LIdentifier name <- satisfy isIdentifier
+  let ident = (\case LIdentifier _ -> True; _ -> False)
-  args <- many (satisfy isIdentifier)
+  _      <- satisfyM (== LBackslash)
-  satisfy (== LAssign)
+  params <- some (satisfyM ident)
-  body <- parseExpression
+  _      <- satisfyM (== LColon)
-  return (SFunc name (map getIdentifier args) body)
+  scnParserM
+  body  <- parseLambdaExpressionM
+  pure $ foldr (\param acc -> SLambda [getIdentifier param] acc) body params
 
-parseAtomicBase :: Parser TricuAST
+parseLambdaExpressionM :: ParserM TricuAST
-parseAtomicBase = choice
+parseLambdaExpressionM = choice
-    [ parseTreeLeaf
+  [ try parseLambdaApplicationM
-    , parseGrouped
+  , parseAtomicLambdaM
   ]
 
-parseLambda :: Parser TricuAST
+parseAtomicLambdaM :: ParserM TricuAST
-parseLambda = between (satisfy (== LOpenParen)) (satisfy (== LCloseParen)) $ do
+parseAtomicLambdaM = choice
-  satisfy (== LBackslash)
+  [ parseVarM
-  param    <- satisfy isIdentifier
+  , parseTreeLeafM
-  rest     <- many (satisfy isIdentifier)
+  , parseLiteralM
-  satisfy (== LColon)
+  , parseListLiteralM
-  body     <- parseLambdaExpression
+  , try parseLambdaM
-  let nestedLambda = foldr (\v acc -> SLambda [v] acc) body (map getIdentifier rest)
+  , between (satisfyM (== LOpenParen)) (satisfyM (== LCloseParen)) parseLambdaExpressionM
-  return (SLambda [getIdentifier param] nestedLambda)
-
-parseLambdaExpression :: Parser TricuAST
-parseLambdaExpression = choice
-  [ try parseLambdaApplication
-  , parseAtomicLambda
   ]
 
-parseAtomicLambda :: Parser TricuAST
+parseApplicationM :: ParserM TricuAST
-parseAtomicLambda = choice
+parseApplicationM = do
-  [ parseVar
+  func <- parseAtomicBaseM
-  , parseTreeLeaf
+  scnParserM
-  , parseLiteral
+  args <- many $ do
-  , parseListLiteral
+    scnParserM
-  , try parseLambda
+    arg <- parseAtomicM
-  , between (satisfy (== LOpenParen)) (satisfy (== LCloseParen)) parseLambdaExpression
+    return arg
+  return $ foldl SApp func args
+
+parseLambdaApplicationM :: ParserM TricuAST
+parseLambdaApplicationM = do
+  func <- parseAtomicLambdaM
+  scnParserM
+  args <- many $ do
+    arg <- parseAtomicLambdaM
+    scnParserM
+    pure arg
+  pure $ foldl SApp func args
+
+parseAtomicBaseM :: ParserM TricuAST
+parseAtomicBaseM = choice
+  [ parseTreeLeafM
+  , parseGroupedM
   ]
 
-parseApplication :: Parser TricuAST
+parseTreeLeafM :: ParserM TricuAST
-parseApplication = do
+parseTreeLeafM = do
-  func <- parseAtomicBase
+  let keyword = (\case LKeywordT -> True; _ -> False)
-  args <- many parseAtomic
+  _ <- satisfyM keyword
-  return $ foldl (\acc arg -> SApp acc arg) func args
+  notFollowedBy $ lift $ satisfy (== LAssign)
+  pure TLeaf
 
-parseLambdaApplication :: Parser TricuAST
+parseTreeTermM :: ParserM TricuAST
-parseLambdaApplication = do
+parseTreeTermM = do
-  func <- parseAtomicLambda
+  base <- parseTreeLeafOrParenthesizedM
-  args <- many parseAtomicLambda
+  rest <- many parseTreeLeafOrParenthesizedM
-  return $ foldl (\acc arg -> SApp acc arg) func args
+  pure (foldl combine base rest)
+  where
+    combine acc next
+      | TLeaf     <- acc = TStem next
+      | TStem t   <- acc = TFork t next
+      | TFork _ _ <- acc = TFork acc next
 
-isTreeTerm :: TricuAST -> Bool
+parseTreeLeafOrParenthesizedM :: ParserM TricuAST
-isTreeTerm TLeaf = True
+parseTreeLeafOrParenthesizedM = choice
-isTreeTerm (TStem _) = True
+  [ between (satisfyM (== LOpenParen)) (satisfyM (== LCloseParen)) parseTreeTermM
-isTreeTerm (TFork _ _) = True
+  , parseTreeLeafM
-isTreeTerm _ = False
+  ]
 
-parseTreeLeaf :: Parser TricuAST
+parseAtomicM :: ParserM TricuAST
-parseTreeLeaf = satisfy isKeywordT *> notFollowedBy (satisfy (== LAssign)) *> pure TLeaf
+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)
+  if | LIdentifier name <- token -> pure (SVar name)
+     | token == LKeywordT        -> pure TLeaf
+     | otherwise                 -> fail "Unexpected token in list item"
+
+parseVarM :: ParserM TricuAST
+parseVarM = do
+  satisfyM (\case LIdentifier _ -> True; _ -> False) >>= \case
+    LIdentifier name
+      | name == "t" || name == "!result" ->
+        fail ("Reserved keyword: " ++ name ++ " cannot be assigned.")
+      | otherwise                         ->
+         pure (SVar name)
+    _ -> fail "Unexpected token while parsing variable"
+
+parseIntLiteralM :: ParserM TricuAST
+parseIntLiteralM = do
+  let intL = (\case LIntegerLiteral _ -> True; _ -> False)
+  token <- satisfyM intL
+  if | LIntegerLiteral value <- token ->
+       pure (SInt value)
+     | otherwise                      ->
+       fail "Unexpected token while parsing integer literal"
+
+parseStrLiteralM :: ParserM TricuAST
+parseStrLiteralM = do
+  let strL = (\case LStringLiteral _ -> True; _ -> False)
+  token <- satisfyM strL
+  if | LStringLiteral value <- token ->
+       pure (SStr value)
+     | otherwise                     ->
+       fail "Unexpected token while parsing string literal"
 
 getIdentifier :: LToken -> String
 getIdentifier (LIdentifier name) = name
-getIdentifier _ = error "Expected identifier"
+getIdentifier _                  = errorWithoutStackTrace "Expected identifier"
 
-parseTreeTerm :: Parser TricuAST
-parseTreeTerm = do
-  base <- parseTreeLeafOrParenthesized
-  rest <- many parseTreeLeafOrParenthesized
-  pure $ foldl combine base rest
-  where
-    combine acc next = case acc of
-      TLeaf -> TStem next
-      TStem t -> TFork t next
-      TFork _ _ -> TFork acc next
-
-parseTreeLeafOrParenthesized :: Parser TricuAST
-parseTreeLeafOrParenthesized = choice
-  [ between (satisfy (== LOpenParen)) (satisfy (== LCloseParen)) parseTreeTerm
-  , parseTreeLeaf
-  ]
-
-foldTree :: [TricuAST] -> TricuAST
-foldTree [] = TLeaf
-foldTree [x] = x
-foldTree (x:y:rest) = TFork x (foldTree (y:rest))
-
-parseAtomic :: Parser TricuAST
-parseAtomic = choice
-  [ parseVar
-  , parseTreeLeaf
-  , parseListLiteral
-  , parseGrouped
-  , parseLiteral
-  ]
-
-parseGrouped :: Parser TricuAST
-parseGrouped = between (satisfy (== LOpenParen)) (satisfy (== LCloseParen)) parseExpression
-
-parseLiteral :: Parser TricuAST
-parseLiteral = choice
-  [ parseIntLiteral
-  , parseStrLiteral
-  ]
-
-parens :: Parser TricuAST -> Parser TricuAST
-parens p = do
-  satisfy (== LOpenParen)
-  result <- p
-  satisfy (== LCloseParen)
-  return result
-
-parseListLiteral :: Parser TricuAST
-parseListLiteral = do
-  satisfy (== LOpenBracket)
-  elements <- many parseListItem
-  satisfy (== LCloseBracket)
-  return (SList elements)
-
-parseListItem :: Parser TricuAST
-parseListItem = choice
-  [ parseGroupedItem
-  , parseListLiteral
-  , parseSingleItem
-  ]
-
-parseGroupedItem :: Parser TricuAST
-parseGroupedItem = do
-  satisfy (== LOpenParen)
-  inner <- parseExpression
-  satisfy (== LCloseParen)
-  return inner
-
-parseSingleItem :: Parser TricuAST
-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 TricuAST
-parseVar = do
-  LIdentifier name <- satisfy isIdentifier
-  if (name == "t" || name == "__result")
-    then fail $ "Reserved keyword: " ++ name ++ " cannot be assigned."
-    else return (SVar name)
-
-parseIntLiteral :: Parser TricuAST
-parseIntLiteral = do
-  LIntegerLiteral value <- satisfy isIntegerLiteral
-  return (SInt value)
-
-parseStrLiteral :: Parser TricuAST
-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
-
--- Alternative parsers
-altSC :: AltParser ()
-altSC = skipMany (char ' ' <|> char '\t' <|> char '\n')
-
-parseTernaryTerm :: AltParser TricuAST
-parseTernaryTerm = do
-  altSC
-  term <- choice parseTernaryTerm'
-  altSC
-  pure term
-  where
-    parseTernaryTerm' =
-      [ try (between (char '(') (char ')') parseTernaryTerm)
-      , try parseTernaryLeaf
-      , try parseTernaryStem
-      , try parseTernaryFork
-      ]
-
-parseTernaryLeaf :: AltParser TricuAST
-parseTernaryLeaf = char '0' *> pure TLeaf
-
-parseTernaryStem :: AltParser TricuAST
-parseTernaryStem = char '1' *> (TStem <$> parseTernaryTerm)
-
-parseTernaryFork :: AltParser TricuAST
-parseTernaryFork = do
-  char '2'
-  term1 <- parseTernaryTerm
-  term2 <- parseTernaryTerm
-  pure $ TFork term1 term2
-
-parseTernary :: String -> Either String TricuAST
-parseTernary input = case runParser (parseTernaryTerm <* eof) "" input of
-  Left err -> Left (errorBundlePretty err)
-  Right ast -> Right ast
-
--- Error Handling
 handleParseError :: ParseErrorBundle [LToken] Void -> String
 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

@@ -20,37 +20,36 @@ repl env = runInputT defaultSettings (loop env)
     loop :: Env -> InputT IO ()
     loop env = do
       minput <- getInputLine "tricu < "
-      case minput of
+      if
-        Nothing -> outputStrLn "Exiting tricu"
+        | Nothing <- minput                     -> outputStrLn "Exiting tricu"
-        Just s -> case strip s of 
+        | Just s  <- minput, strip s == "!exit" -> outputStrLn "Exiting tricu"
-          "!exit" -> outputStrLn "Exiting tricu"
+        | Just s  <- minput, strip s == ""      -> do
-          "!load" -> do
-            path <- getInputLine "File path to load < "
-            case path of
-              Nothing -> do
-                outputStrLn "No input received; stopping import."
-                loop env
-              Just path -> do
-                loadedEnv <- liftIO $ evaluateFileWithContext env (strip path)
-                loop $ Map.delete "__result" (Map.union loadedEnv env)
-          "" -> do
           outputStrLn ""
           loop env
-          input -> do
+        | Just s  <- minput, strip s == "!import" -> do
-            case (take 2 input) of 
+          path <- getInputLine "File path to load < "
-              "--" -> loop env
+          if
-              _ -> do
+            | Nothing <- path -> do
-                newEnv <- liftIO $ (processInput env input `catch` errorHandler env)
+              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
-      case Map.lookup "__result" newEnv of
+      if
-        Just r -> do
+        | Just r <- Map.lookup "!result" newEnv -> do
           putStrLn $ "tricu > " ++ decodeResult r
-        Nothing -> return ()
+        | otherwise -> return ()
       return newEnv
     
     errorHandler :: Env -> SomeException -> IO (Env)
@@ -60,12 +59,3 @@ repl env = runInputT defaultSettings (loop env)
     
     strip :: String -> String
     strip = dropWhileEnd isSpace . dropWhile isSpace
-
-decodeResult :: T -> String
-decodeResult tc = case toNumber tc of
-  Right num -> show num
-  Left _ -> case toString tc of
-    Right str -> "\"" ++ str ++ "\""
-    Left _ -> case toList tc of
-      Right list -> "[" ++ intercalate ", " (map decodeResult list) ++ "]"
-      Left _ -> formatResult TreeCalculus tc

src/Research.hs

@@ -19,16 +19,18 @@ data TricuAST
   | SInt Int
   | SStr String
   | SList [TricuAST]
-  | SFunc String [String] TricuAST
+  | SDef String [String] TricuAST
   | SApp TricuAST TricuAST
   | TLeaf
   | TStem TricuAST
   | TFork TricuAST TricuAST
   | SLambda [String] TricuAST
   | SEmpty
+  | SModule String
+  | SImport String String
   deriving (Show, Eq, Ord)
 
--- Tokens from Lexer
+-- Lexer Tokens
 data LToken
   = LKeywordT
   | LIdentifier String
@@ -42,10 +44,12 @@ data LToken
   | LOpenBracket
   | LCloseBracket
   | LNewline
+  | LModule String
+  | LImport String String
   deriving (Show, Eq, Ord)
 
 -- Output formats
-data EvaluatedForm = TreeCalculus | FSL | AST | Ternary | Ascii
+data EvaluatedForm = TreeCalculus | FSL | AST | Ternary | Ascii | Decode
   deriving (Show, Data, Typeable)
 
 -- Environment containing previously evaluated TC terms
@@ -61,19 +65,6 @@ 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
 
--- 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
@@ -128,6 +119,7 @@ formatResult FSL          = show
 formatResult AST          = show . toAST
 formatResult Ternary      = toTernaryString
 formatResult Ascii        = toAscii
+formatResult Decode       = decodeResult
 
 toSimpleT :: String -> String
 toSimpleT s = T.unpack 
@@ -160,4 +152,9 @@ toAscii tree = go tree "" True
         ++ go left (prefix ++ (if isLast then "    " else "|   ")) False
         ++ go right (prefix ++ (if isLast then "    " else "|   ")) True
 
--- Utility
+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

test/Spec.hs

@@ -9,6 +9,7 @@ import Research
 
 import Control.Exception      (evaluate, try, SomeException)
 import Control.Monad.IO.Class (liftIO)
+import Data.List              (isInfixOf)
 import Test.Tasty
 import Test.Tasty.HUnit
 import Test.Tasty.QuickCheck
@@ -25,185 +26,217 @@ runTricu s = show $ result (evalTricu Map.empty $ parseTricu s)
 
 tests :: TestTree
 tests = testGroup "Tricu Tests"
-  [ lexerTests
+  [ lexer
-  , parserTests
+  , parser
-  , evaluationTests
+  , simpleEvaluation
-  , lambdaEvalTests
+  , lambdas
-  , libraryTests
+  , baseLibrary
-  , fileEvaluationTests
+  , fileEval
-  , propertyTests
+  , modules
+  , demos
   ]
 
-lexerTests :: TestTree
+lexer :: TestTree
-lexerTests = testGroup "Lexer Tests"
+lexer = 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 tricuLexer "" input @?= expect
+
   , testCase "Lex Tree Calculus terms" $ do
       let input = "t t t"
           expect = Right [LKeywordT, LKeywordT, LKeywordT]
       runParser tricuLexer "" input @?= expect
+
   , testCase "Lex escaped characters in strings" $ do
       let input = "\"hello\\nworld\""
           expect = Right [LStringLiteral "hello\\nworld"]
       runParser tricuLexer "" input @?= expect
+
   , testCase "Lex mixed literals" $ do
       let input = "t \"string\" 42"
           expect = Right [LKeywordT, LStringLiteral "string", LIntegerLiteral 42]
       runParser tricuLexer "" input @?= expect
+
   , testCase "Lex invalid token" $ do
       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 tricuLexer "" input) of
         Left _ -> assertFailure "Failed to lex input"
         Right i -> i @?= expect
+
   , testCase "Error when using invalid characters in identifiers" $ do
-        case (runParser tricuLexer "" "__result = 5") of
+        case (runParser tricuLexer "" "!result = 5") of
           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
+parser :: TestTree
-parserTests = testGroup "Parser Tests"
+parser = testGroup "Parser Tests"
   [ testCase "Error when assigning a value to T" $ do
-      let input = lexTricu "t = x"
+      let tokens = lexTricu "t = x" 
-      case (runParser parseExpression "" input) of
+      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)"
-          expect = SFunc "x" [] (SLambda ["a"] (SLambda ["b"] (SLambda ["c"] (SVar "a"))))
+          expect = SDef "x" [] (SLambda ["a"] (SLambda ["b"] (SLambda ["c"] (SVar "a"))))
       parseSingle input @?= expect
+
   , testCase "Parse nested Tree Calculus terms" $ do
       let input = "t (t t) t"
           expect = SApp (SApp TLeaf (SApp TLeaf TLeaf)) TLeaf
       parseSingle input @?= expect
+
   , testCase "Parse sequential Tree Calculus terms" $ do
       let input = "t t t"
           expect = SApp (SApp TLeaf TLeaf) TLeaf
       parseSingle input @?= expect
+
   , testCase "Parse mixed list literals" $ do
       let input = "[t (\"hello\") t]"
           expect = SList [TLeaf, SStr "hello", TLeaf]
       parseSingle input @?= expect
+
   , testCase "Parse function with applications" $ do
       let input  = "f = (\\x : t x)"
-          expect = SFunc "f" [] (SLambda ["x"] (SApp TLeaf (SVar "x")))
+          expect = SDef "f" [] (SLambda ["x"] (SApp TLeaf (SVar "x")))
       parseSingle input @?= expect
+
   , testCase "Parse nested lists" $ do
       let input  = "[t [(t t)]]"
           expect = SList [TLeaf,SList [SApp TLeaf TLeaf]]
       parseSingle input @?= expect
+
   , testCase "Parse complex parentheses" $ do
       let input  = "t (t t (t t))"
           expect = SApp TLeaf (SApp (SApp TLeaf TLeaf) (SApp TLeaf TLeaf))
       parseSingle input @?= expect
+
   , testCase "Parse empty list" $ do
       let input  = "[]"
           expect = SList []
       parseSingle input @?= expect
+
   , testCase "Parse multiple nested lists" $ do
       let input  = "[[t t] [t (t t)]]"
           expect = SList [SList [TLeaf,TLeaf],SList [TLeaf,SApp TLeaf TLeaf]]
       parseSingle input @?= expect
+
   , testCase "Parse whitespace variance" $ do
       let input1 = "[t t]"
       let input2 = "[ t t ]"
           expect = SList [TLeaf, TLeaf]
       parseSingle input1 @?= expect
       parseSingle input2 @?= expect
+
   , testCase "Parse string in list" $ do
       let input  = "[(\"hello\")]"
           expect = SList [SStr "hello"]
       parseSingle input @?= expect
+
   , testCase "Parse parentheses inside list" $ do
       let input  = "[t (t t)]"
           expect = SList [TLeaf,SApp TLeaf TLeaf]
       parseSingle input @?= expect
+
   , testCase "Parse nested parentheses in function body" $ do
       let input  = "f = (\\x : t (t (t t)))"
-          expect = SFunc "f" [] (SLambda ["x"] (SApp TLeaf (SApp TLeaf (SApp TLeaf TLeaf))))
+          expect = SDef "f" [] (SLambda ["x"] (SApp TLeaf (SApp TLeaf (SApp TLeaf TLeaf))))
       parseSingle input @?= expect
+
   , testCase "Parse lambda abstractions" $ do
       let input  = "(\\a : a)"
           expect = (SLambda ["a"] (SVar "a"))
       parseSingle input @?= expect
+
   , testCase "Parse multiple arguments to lambda abstractions" $ do
       let input  = "x = (\\a b : a)"
-          expect = SFunc "x" [] (SLambda ["a"] (SLambda ["b"] (SVar "a")))
+          expect = SDef "x" [] (SLambda ["a"] (SLambda ["b"] (SVar "a")))
       parseSingle input @?= expect
+
   , 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]
+          expect = [SDef "x" [] (SLambda ["a"] (SVar "a")),SApp (SVar "x") TLeaf]
       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
-  , testCase "Comments with no terms" $ do
-      let input = unlines ["-- (t)", "(t t)"]
-          expect = [SEmpty,SApp TLeaf TLeaf]
-      parseTricu input @?= expect 
   ]
 
-evaluationTests :: TestTree
+simpleEvaluation :: TestTree
-evaluationTests = testGroup "Evaluation Tests"
+simpleEvaluation = testGroup "Evaluation Tests"
   [ testCase "Evaluate single Leaf" $ do
       let input = "t"
       let ast = parseSingle input
       (result $ evalSingle Map.empty ast) @?= Leaf
+
   , testCase "Evaluate single Stem" $ do
       let input = "t t"
       let ast = parseSingle input
       (result $ evalSingle Map.empty ast) @?= Stem Leaf
+
   , testCase "Evaluate single Fork" $ do
       let input = "t t t"
       let ast = parseSingle input
       (result $ evalSingle Map.empty ast) @?= Fork Leaf Leaf
+
   , testCase "Evaluate nested Fork and Stem" $ do
       let input = "t (t t) t"
       let ast = parseSingle input
       (result $ evalSingle Map.empty ast) @?= Fork (Stem Leaf) Leaf
+
   , testCase "Evaluate `not` function" $ do
       let input = "t (t (t t) (t t t)) t"
       let ast = parseSingle input
       (result $ evalSingle Map.empty ast) @?=
         Fork (Fork (Stem Leaf) (Fork Leaf Leaf)) Leaf
+
   , testCase "Environment updates with definitions" $ do
       let input = "x = t\ny = x"
           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 = evalTricu Map.empty (parseTricu input)
       (result env) @?= Stem (Stem Leaf)
+
   , testCase "Multiline input evaluation" $ do
       let input = "x = t\ny = t t\nx"
           env = evalTricu Map.empty (parseTricu input)
       (result env) @?= Leaf
+
   , testCase "Evaluate string literal" $ do
       let input = "\"hello\""
       let ast = parseSingle input
       (result $ evalSingle Map.empty ast) @?= ofString "hello"
+
   , testCase "Evaluate list literal" $ do
       let input = "[t (t t)]"
       let ast = parseSingle input
       (result $ evalSingle Map.empty ast) @?= ofList [Leaf, Stem Leaf]
+
   , testCase "Evaluate empty list" $ do
       let input = "[]"
       let ast = parseSingle input
       (result $ evalSingle Map.empty ast) @?= ofList []
+
   , testCase "Evaluate variable dependency chain" $ do
       let input = "x = t (t t)\n \
                   \ y = x\n \
@@ -212,10 +245,17 @@ evaluationTests = testGroup "Evaluation Tests"
                   \ variablewithamuchlongername"
           env = evalTricu Map.empty (parseTricu input)
       (result env) @?= (Stem (Stem Leaf))
-  , testCase "Evaluate variable shadowing" $ do
+
+
+  , testCase "Immutable definitions" $ do
       let input = "x = t t\nx = t\nx"
           env = evalTricu Map.empty (parseTricu input)
-      (result env) @?= Leaf
+      result <- try (evaluate (runTricu input)) :: IO (Either SomeException String)
+      case result of
+        Left  _ -> return ()
+        Right _ -> assertFailure "Expected evaluation error"
+
+
   , testCase "Apply identity to Boolean Not" $ do
       let not = "(t (t (t t) (t t t)) t)"
       let input = "x = (\\a : a)\nx " ++ not
@@ -223,204 +263,291 @@ evaluationTests = testGroup "Evaluation Tests"
       result env @?= Fork (Fork (Stem Leaf) (Fork Leaf Leaf)) Leaf
   ]
 
-lambdaEvalTests :: TestTree
+lambdas :: TestTree
-lambdaEvalTests = testGroup "Lambda Evaluation Tests"
+lambdas = testGroup "Lambda Evaluation Tests"
   [ testCase "Lambda Identity Function" $ do
       let input = "id = (\\x : x)\nid t"
       runTricu input @?= "Leaf"
+
   , testCase "Lambda Constant Function (K combinator)" $ do
       let input = "k = (\\x y : x)\nk t (t t)"
       runTricu input @?= "Leaf"
+
   , testCase "Lambda Application with Variable" $ do
       let input = "id = (\\x : x)\nval = t t\nid val"
       runTricu input @?= "Stem Leaf"
+
   , testCase "Lambda Application with Multiple Arguments" $ do
       let input = "apply = (\\f x y : f x y)\nk = (\\a b : a)\napply k t (t t)"
       runTricu input @?= "Leaf"
+
    , testCase "Nested Lambda Application" $ do
       let input = "apply = (\\f x y : f x y)\nid = (\\x : x)\napply (\\f x : f x) id t"
       runTricu input @?= "Leaf"
+
   , testCase "Lambda with a complex body" $ do
       let input = "f = (\\x : t (t x))\nf t"
       runTricu input @?= "Stem (Stem Leaf)"
+
   , testCase "Lambda returning a function" $ do
       let input = "f = (\\x : (\\y : x))\ng = f t\ng (t t)"
       runTricu input @?= "Leaf"
+
   , testCase "Lambda with Shadowing" $ do
       let input = "f = (\\x : (\\x : x))\nf t (t t)"
       runTricu input @?= "Stem Leaf"
+
    , testCase "Lambda returning another lambda" $ do
       let input = "k = (\\x : (\\y : x))\nk_app = k t\nk_app (t t)"
       runTricu input @?= "Leaf"
+
    , testCase "Lambda with free variables" $ do
       let input = "y = t t\nf = (\\x : y)\nf t"
       runTricu input @?= "Stem Leaf"
+
    , testCase "SKI Composition" $ do
       let input = "s = (\\x y z : x z (y z))\nk = (\\x y : x)\ni = (\\x : x)\ncomp = s k i\ncomp t (t t)"
       runTricu input @?= "Stem (Stem Leaf)"
+
    , testCase "Lambda with multiple parameters and application" $ do
       let input = "f = (\\a b c : t a b c)\nf t (t t) (t t t)"
       runTricu input @?= "Stem Leaf"
+
    , testCase "Lambda with nested application in the body" $ do
       let input = "f = (\\x : t (t (t x)))\nf t"
       runTricu input @?= "Stem (Stem (Stem Leaf))"
+
     , testCase "Lambda returning a function and applying it" $ do
         let input = "f = (\\x : (\\y : t x y))\ng = f t\ng (t t)"
         runTricu input @?= "Fork Leaf (Stem Leaf)"
+
     , testCase "Lambda applying a variable" $ do
         let input = "id = (\\x : x)\na = t t\nid a"
         runTricu input @?= "Stem Leaf"
+
     , testCase "Nested lambda abstractions in the same expression" $ do
         let input = "f = (\\x : (\\y : x y))\ng = (\\z : z)\nf g t"
         runTricu input @?= "Leaf"
+
   , testCase "Lambda with a string literal" $ do
         let input = "f = (\\x : x)\nf \"hello\""
         runTricu input @?= "Fork (Fork Leaf (Fork Leaf (Fork Leaf (Fork (Stem Leaf) (Fork Leaf (Fork (Stem Leaf) (Fork (Stem Leaf) Leaf))))))) (Fork (Fork (Stem Leaf) (Fork Leaf (Fork (Stem Leaf) (Fork Leaf (Fork Leaf (Fork (Stem Leaf) (Fork (Stem Leaf) Leaf))))))) (Fork (Fork Leaf (Fork Leaf (Fork (Stem Leaf) (Fork (Stem Leaf) (Fork Leaf (Fork (Stem Leaf) (Fork (Stem Leaf) Leaf))))))) (Fork (Fork Leaf (Fork Leaf (Fork (Stem Leaf) (Fork (Stem Leaf) (Fork Leaf (Fork (Stem Leaf) (Fork (Stem Leaf) Leaf))))))) (Fork (Fork (Stem Leaf) (Fork (Stem Leaf) (Fork (Stem Leaf) (Fork (Stem Leaf) (Fork Leaf (Fork (Stem Leaf) (Fork (Stem Leaf) Leaf))))))) Leaf))))"
+
+
    , testCase "Lambda with an integer literal" $ do
         let input = "f = (\\x : x)\nf 42"
         runTricu input @?= "Fork Leaf (Fork (Stem Leaf) (Fork Leaf (Fork (Stem Leaf) (Fork Leaf (Fork (Stem Leaf) Leaf)))))"
+
    , testCase "Lambda with a list literal" $ do
         let input = "f = (\\x : x)\nf [t (t t)]"
         runTricu input @?= "Fork Leaf (Fork (Stem Leaf) Leaf)"
   ]
 
-libraryTests :: TestTree
+baseLibrary :: TestTree
-libraryTests = testGroup "Library Tests"
+baseLibrary = 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"
+      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"
+      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"
+      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)"
+      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)"
+      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)"
+      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)"
+      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 []"
+      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)])"
+      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)"
+      let input = "equal? (t t t) (t t t)"
           env = evalTricu library (parseTricu input)
       result env @?= Stem Leaf
   ]
 
-fileEvaluationTests :: TestTree
+fileEval :: TestTree
-fileEvaluationTests = testGroup "Evaluation tests"
+fileEval = testGroup "File 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"
+      library <- liftIO $ evaluateFile "./lib/base.tri"
-      res @?= Stem Leaf
+      fEnv    <- liftIO $ evaluateFileWithContext library "./test/map.tri"
+      (mainResult fEnv) @?= Stem Leaf
+
   , testCase "Eval and decoding string" $ do
       library <- liftIO $ evaluateFile "./lib/base.tri"
       res <- liftIO $ evaluateFileWithContext library "./test/string.tri"
       decodeResult (result res) @?= "\"String test!\""
   ]
 
-propertyTests :: TestTree
+modules :: TestTree
-propertyTests = testGroup "Property Tests"
+modules = testGroup "Test modules"
-  [ testProperty "Lexing and parsing round-trip" $ \input ->
+  [ testCase "Detect cyclic dependencies" $ do
-      case runParser tricuLexer "" input of
+      result <- try (liftIO $ evaluateFileResult "./test/cycle-1.tri") :: IO (Either SomeException T)
-        Left _ -> property True
+      case result of
-        Right tokens -> case runParser parseExpression "" tokens of
+        Left e -> do
-          Left _ -> property True
+          let errorMsg = show e
-          Right ast -> parseSingle input === ast
+          if "Encountered cyclic import" `isInfixOf` errorMsg
+            then return ()
+            else assertFailure $ "Unexpected error: " ++ errorMsg
+        Right _ -> assertFailure "Expected cyclic dependencies"
+  , testCase "Module imports and namespacing" $ do
+      res <- liftIO $ evaluateFileResult "./test/namespace-A.tri"
+      res @?= Leaf
+  , testCase "Multiple imports" $ do
+      res <- liftIO $ evaluateFileResult "./test/vars-A.tri"
+      res @?= Leaf
+  , testCase "Error on unresolved variable" $ do
+      result <- try (liftIO $ evaluateFileResult "./test/unresolved-A.tri") :: IO (Either SomeException T)
+      case result of
+        Left e -> do
+          let errorMsg = show e
+          if "undefinedVar" `isInfixOf` errorMsg
+            then return ()
+            else assertFailure $ "Unexpected error: " ++ errorMsg
+        Right _ -> assertFailure "Expected unresolved variable error"
+  , testCase "Multi-level imports" $ do
+      res <- liftIO $ evaluateFileResult "./test/multi-level-A.tri"
+      res @?= Leaf
+  , testCase "Lambda expression namespaces" $ do
+      res <- liftIO $ evaluateFileResult "./test/lambda-A.tri"
+      res @?= Leaf
+  ]
+
+
+-- All of our demo tests are also module tests
+demos :: TestTree
+demos = testGroup "Test provided demo functionality"
+  [ testCase "Structural equality demo" $ do
+      res     <- liftIO $ evaluateFileResult "./demos/equality.tri"
+      decodeResult res @?= "t t"
+  , testCase "Convert values back to source code demo" $ do
+      res     <- liftIO $ evaluateFileResult "./demos/toSource.tri"
+      decodeResult res @?= "\"(t (t (t t) (t t t)) (t t (t t t)))\""
+  , testCase "Determining the size of functions" $ do
+      res     <- liftIO $ evaluateFileResult "./demos/size.tri"
+      decodeResult res @?= "454"
+  , testCase "Level Order Traversal demo" $ do
+      res     <- liftIO $ evaluateFileResult "./demos/levelOrderTraversal.tri"
+      decodeResult res @?= "\"\n1 \n2 3 \n4 5 6 7 \n8 11 10 9 12 \""
   ]

test/comments-1.tri

@@ -2,7 +2,7 @@
 -- t (t t) (t (t t t))
 -- t (t t t) (t t)
 -- x = (\a : a)
-t (t t) t -- Fork (Stem Leaf) Leaf
+main = t (t t) t -- Fork (Stem Leaf) Leaf
 -- t t
 -- x
 -- x = (\a : a)

test/cycle-1.tri

@@ -0,0 +1,5 @@
+!module Cycle
+
+!import "test/cycle-2.tri" Cycle2
+
+cycle1 = t Cycle2.cycle2

test/cycle-2.tri

@@ -0,0 +1,5 @@
+!module Cycle2
+
+!import "test/cycle-1.tri" Cycle1
+
+cycle2 = t Cycle1.cycle1

test/fork.tri

@@ -1 +1 @@
-t t t 
+main = t t t 

test/lambda-A.tri

@@ -0,0 +1,2 @@
+!module A
+main = (\x : x) t

test/map.tri

@@ -1,24 +1,2 @@
-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!")]
+main = equal? x [("Successfully concatenated two strings!")]

test/modules-1.tri

@@ -0,0 +1,5 @@
+!module Test
+
+!import "lib/base.tri" Lib
+
+main = Lib.not? t

test/modules-2.tri

@@ -0,0 +1 @@
+n = t t t

test/multi-level-A.tri

@@ -0,0 +1,3 @@
+!module A
+!import "./test/multi-level-B.tri" B
+main = B.main

test/multi-level-B.tri

@@ -0,0 +1,3 @@
+!module B
+!import "./test/multi-level-C.tri" C
+main = C.val

test/multi-level-C.tri

@@ -0,0 +1,2 @@
+!module C
+val = t

test/namespace-A.tri

@@ -0,0 +1,3 @@
+!module A
+!import "./test/namespace-B.tri" B
+main = B.x

test/namespace-B.tri

@@ -0,0 +1,2 @@
+!module B
+x = t

test/size.tri

@@ -0,0 +1,21 @@
+compose = \f g x : f (g x)
+
+succ = y (\self :
+  triage
+    1
+    t
+    (triage
+      (t (t t))
+      (\_ tail : t t (self tail))
+      t))
+
+size = (\x :
+  (y (\self x :
+    compose succ
+      (triage
+        (\x : x)
+        self
+        (\x y : compose (self x) (self y))
+        x)) x 0))
+
+size size

test/undefined.tri

@@ -0,0 +1 @@
+namedTerm = undefinedForTesting

test/unresolved-A.tri

@@ -0,0 +1,2 @@
+!module A
+main = undefinedVar

test/vars-A.tri

@@ -0,0 +1,7 @@
+!module A
+
+!import "./test/vars-B.tri" B
+
+!import "./test/vars-C.tri" C
+
+main = B.y (C.z)

test/vars-B.tri

@@ -0,0 +1,2 @@
+!module B
+y = \x : x

test/vars-C.tri

@@ -0,0 +1,2 @@
+!module C
+z = t

tricu.cabal

@@ -1,7 +1,7 @@
 cabal-version: 1.12
 
 name:           tricu
-version:        0.5.0
+version:        0.12.0
 description:    A micro-language for exploring Tree Calculus
 author:         James Eversole
 maintainer:     james@eversole.co
@@ -18,6 +18,8 @@ executable tricu
       src
   default-extensions:
       DeriveDataTypeable
+      LambdaCase
+      MultiWayIf
       OverloadedStrings
   ghc-options: -threaded -rtsopts -with-rtsopts=-N -optl-pthread -fPIC
   build-depends:
@@ -43,6 +45,8 @@ test-suite tricu-tests
   hs-source-dirs:      test, src
   default-extensions:
       DeriveDataTypeable
+      LambdaCase
+      MultiWayIf
       OverloadedStrings
   build-depends:       
     base