# File eval mode now relies on main function

To encourage organizing code in a way that helps in understanding, I
have implemented the common idiom of requiring a `main` function. In
tricu and other functional languages, it is usually placed near the top
of the module. The evaluator gracefully handles the situation of passing
multiple files where the intermediary "library" files do not have main functions.

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

@@ -54,16 +54,12 @@ jobs:
           cp -L ./result/bin/tricu ./tricu
           chmod 755 ./tricu
           nix develop --command upx ./tricu
-  
-      - name: Setup go for release action
-        uses: actions/setup-go@v5
-        with:
-          go-version: '>=1.20.1'
-  
+
       - name: Release binary
-        uses: https://gitea.com/actions/release-action@main
+        uses: akkuman/gitea-release-action@v1
         with:
           files: |-
             ./tricu
-          api_key: '${{ secrets.RELEASE_TOKEN }}'
+          token: '${{ secrets.RELEASE_TOKEN }}'
+          body: '${{ gitea.event.head_commit.message }}'
           pre_release: true

README.md

@@ -71,7 +71,7 @@ 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]

demos/equality.tri

@@ -1,3 +1,5 @@
+main = lambdaEqualsTC
+
 -- We represent `false` with a Leaf and `true` with a Stem Leaf
 demo_false = t
 demo_true  = t t

demos/levelOrderTraversal.tri

@@ -1,3 +1,4 @@
+main = exampleTwo
 -- Level Order Traversal of a labelled binary tree
 -- Objective: Print each "level" of the tree on a separate line
 --
@@ -58,5 +59,3 @@ 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/size.tri

@@ -1,3 +1,5 @@
+main = size size
+
 compose = \f g x : f (g x)
 
 succ = y (\self :
@@ -17,5 +19,3 @@ size = (\x :
         self
         (\x y : compose (self x) (self y))
         x)) x 0))
-
-size size

demos/toSource.tri

@@ -1,3 +1,4 @@
+main = toSource 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.

src/Eval.hs

@@ -179,3 +179,8 @@ result :: Env -> T
 result r = case Map.lookup "__result" r of
   Just a -> a
   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

@@ -13,9 +13,9 @@ evaluateFileResult filePath = do
   contents <- readFile filePath
   let asts = parseTricu contents
   let finalEnv = evalTricu Map.empty asts
-  case Map.lookup "__result" finalEnv of
+  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

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."
@@ -70,10 +70,10 @@ 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

src/REPL.hs

@@ -59,10 +59,3 @@ repl env = runInputT defaultSettings (loop env)
     
     strip :: String -> String
     strip = dropWhileEnd isSpace . dropWhile isSpace
-
-decodeResult :: T -> String
-decodeResult tc
-  | Right num  <- toNumber tc = show num
-  | Right str  <- toString tc = "\"" ++ str ++ "\""
-  | Right list <- toList tc   = "[" ++ intercalate ", " (map decodeResult list) ++ "]"
-  | otherwise                 = formatResult TreeCalculus tc

src/Research.hs

@@ -45,7 +45,7 @@ data LToken
   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
@@ -115,6 +115,7 @@ formatResult FSL          = show
 formatResult AST          = show . toAST
 formatResult Ternary      = toTernaryString
 formatResult Ascii        = toAscii
+formatResult Decode       = decodeResult
 
 toSimpleT :: String -> String
 toSimpleT s = T.unpack 
@@ -147,4 +148,9 @@ 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

@@ -488,8 +488,9 @@ fileEval = testGroup "File evaluation tests"
       res @?= Fork (Stem Leaf) Leaf
 
   , testCase "Mapping and Equality" $ do
-      res <- liftIO $ evaluateFileResult "./test/map.tri"
-      res @?= Stem Leaf
+      library <- liftIO $ evaluateFile "./lib/base.tri"
+      fEnv    <- liftIO $ evaluateFileWithContext library "./test/map.tri"
+      (mainResult fEnv) @?= Stem Leaf
 
   , testCase "Eval and decoding string" $ do
       library <- liftIO $ evaluateFile "./lib/base.tri"

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/fork.tri

@@ -1 +1 @@
-t t t 
+main = t t 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!")]

tricu.cabal

@@ -1,7 +1,7 @@
 cabal-version: 1.12
 
 name:           tricu
-version:        0.10.0
+version:        0.11.0
 description:    A micro-language for exploring Tree Calculus
 author:         James Eversole
 maintainer:     james@eversole.co