Some special characters in ids; new demos

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.

README.md

@@ -29,11 +29,11 @@ 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 < test (t t)
 tricu > "Stem"
-tricu < -- We can even write a function to convert a function to source code
-tricu < toTString id
-tricu > "t (t (t t)) t"
+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

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

@@ -17,20 +17,15 @@
 --   4   5    6
 --
 
-isLeaf = (\node : 
-  lOr 
-    (emptyList node) 
-    (emptyList (tail node)))
+label = (\node : head node)
 
-getLabel = (\node : head node)
-
-getLeft  = (\node : if (emptyList node) 
+left  = (\node : if (emptyList node) 
   [] 
   (if (emptyList (tail node)) 
     [] 
     (head (tail node))))
 
-getRight = (\node : if (emptyList node) 
+right = (\node : if (emptyList node) 
   [] 
   (if (emptyList (tail node)) 
     [] 
@@ -40,11 +35,11 @@ getRight = (\node : if (emptyList node)
 
 processLevel = y (\self queue : if (emptyList queue) 
   [] 
-  (pair (map getLabel queue) (self (filter 
+  (pair (map label queue) (self (filter 
     (\node : not (emptyList node)) 
-      (lconcat (map getLeft queue) (map getRight queue))))))
+      (lconcat (map left queue) (map right queue))))))
 
-levelOrderTraversal = (\a : processLevel (t a t))
+levelOrderTraversal_ = (\a : processLevel (t a t))
 
 toLineString = y (\self levels : if (emptyList levels) 
   "" 
@@ -52,17 +47,19 @@ toLineString = y (\self levels : if (emptyList levels)
     (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))
+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]]]
+levelOrderTraversal = (\s : lconcat (t 10 t) (flatten (levelOrderToString s)))
 
-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]]]
+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)))"

lib/base.tri

@@ -1,22 +1,25 @@
 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)
+_     = 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)
-pair = t
+test   = triage "Leaf" (\_ : "Stem") (\_ _ : "Fork")
 
 matchBool = (\ot of : triage 
   of 
@@ -36,58 +39,58 @@ matchPair = (\op : triage
   op
 )
 
-not = matchBool false true
-and = matchBool id (\z : false)
-if = (\cond then else : t (t else (t t then)) t cond)
-test = triage "Leaf" (\z : "Stem") (\a b : "Fork")
+not? = matchBool false true
+and? = matchBool id (\_ : false)
+emptyList? = matchList true (\_ _ : false)
 
-emptyList = matchList true (\y z : false)
-head = matchList t (\hd tl : hd)
-tail = matchList t (\hd tl : tl)
+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 
-  (\x : false) 
-  (\_ x : x) 
+  (\_     : false) 
+  (\_ x   : x) 
   (\_ _ x : x)
 )
 
 lOr = (triage 
-  (\x : x) 
-  (\_ _ : true) 
-  (\_ _ x : true)
+  (\x     : x) 
+  (\_ _   : true) 
+  (\_ _ _ : true)
 )
 
-hmap = y (\self : 
+map_ = y (\self : 
   matchList 
-    (\f : t) 
-    (\hd tl f : pair 
-                  (f hd) 
-                  (self tl f)))
-map = (\f l : hmap l f)
+    (\_ : t) 
+    (\head tail f : pair (f head) (self tail f)))
+map = (\f l : map_ l f)
 
-equal = y (\self : triage 
+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))))
+    (\_   : false) 
+    (\_ _ : false)) 
+  (\ax : 
+    triage 
+      false 
+      (self ax) 
+      (\_ _ : false)) 
+  (\ax ay : 
+    triage 
+      false 
+      (\_ : false) 
+      (\bx by : lAnd (self ax bx) (self ay by))))
 
-hfilter = y (\self : matchList (\f : t) (\hd tl f : matchBool (t hd) i (f hd) (self tl f)))
-filter  = (\f l : hfilter l f)
+filter_ = y (\self : matchList 
+  (\_ : t) 
+  (\head tail f : matchBool (t head) i (f head) (self tail f)))
+filter  = (\f l : filter_ l f)
 
-hfoldl  = y (\self f l x : matchList (\acc : acc) (\hd tl acc : self f tl (f acc hd)) l x)
-foldl   = (\f x l : hfoldl f l x)
+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)
 
-hfoldr  = y (\self x f l : matchList x (\hd tl : f (self x f tl) hd) l)
-foldr   = (\f x l : hfoldr x f l)
+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/Lexer.hs

@@ -18,7 +18,10 @@ 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")
     then fail "Keywords (`t`, `__result`) cannot be used as an identifier"

test/Spec.hs

@@ -308,7 +308,7 @@ libraryTests = testGroup "Library Tests"
       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
@@ -328,32 +328,32 @@ libraryTests = testGroup "Library Tests"
       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
@@ -373,12 +373,12 @@ libraryTests = testGroup "Library Tests"
       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
@@ -388,7 +388,7 @@ libraryTests = testGroup "Library Tests"
       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
   ]