Attach contracts to definitions

Contracts now live directly on definitions via @ / =@ annotations and
travel automatically with exported values.

- Remove !export from lexer/parser/AST/evaluator/manifest/resolver and CLI.
- Simplify workspace module export logic: export all top-level local
  definitions by default.
- Update Frontend.ContractDesugar:
  - Named binder annotations (x@nat?) expand to per-argument withContract.
  - Phantom annotations (@nat?) expand to a local raw helper plus a wrapper,
    keeping fixed points shared and only depending on withContract.
- Merge lib/guardedBase.tri into lib/base.tri and annotate partial/sensitive
  base functions: head, tail, last, add, sub, mul, div, mod, pow, min,
  max, length, sum, product.
- Add check contract helper to lib/base.tri.
- Update demos/contractBasics.tri and README to reflect @/=@-only design.
- Update test suite: remove guardedBase import, replace explicit !export
  test with a test verifying that contract annotations on an exported
  definition are enforced on import.
- Fix remaining base.tri definitions (div/mod/pow) to stay point-free.

test/Spec.hs

@@ -19,7 +19,7 @@ import qualified Network.Socket as NS
 import Control.Monad         (forM, forM_)
 import Control.Monad.IO.Class (liftIO)
 import System.IO.Temp         (withSystemTempDirectory)
-import System.Directory      (createDirectory, doesFileExist, doesDirectoryExist, listDirectory)
+import System.Directory      (createDirectory, doesFileExist, doesDirectoryExist, listDirectory, getCurrentDirectory)
 import System.FilePath       ((</>))
 import Data.Bits              (xor)
 import Data.Char              (digitToInt)
@@ -58,8 +58,7 @@ allTestLibsEnv = unsafePerformIO $ do
   io      <- evaluateFile "./lib/io.tri"
   sock    <- evaluateFile "./lib/socket.tri"
   intensional   <- evaluateFile "./lib/intensionalContracts.tri"
-  guarded       <- evaluateFile "./lib/guardedBase.tri"
-  pure (Map.unions [base, bytes, bin, http, arbor, io, sock, intensional, guarded])
+  pure (Map.unions [base, bytes, bin, http, arbor, io, sock, intensional])
 {-# NOINLINE allTestLibsEnv #-}
 
 tests :: TestTree
@@ -1678,7 +1677,7 @@ demos = testGroup "Test provided demo functionality"
       decodeResult res @?= "[t t, 10]"
   , testCase "Safe base wrappers demo" $ do
       res     <- liftIO $ evaluateFileResult "./demos/contractBasics.tri"
-      decodeResult res @?= "[t t, 1]"
+      decodeResult res @?= "[3, t t, t, t t]"
   ]
 
 decoding :: TestTree
@@ -1942,7 +1941,6 @@ contentStoreTests = testGroup "Content Store Tests"
                   "main"
                   (ObjectRef (unDomain treeTermDomain) root)
                   "arboricx.abi.tree.v1"
-                  Nothing
               ]
         root <- putTreeTerm store term
         h <- putManifest store (manifestFor root)
@@ -1959,7 +1957,6 @@ contentStoreTests = testGroup "Content Store Tests"
                 "value"
                 (ObjectRef (unDomain treeTermDomain) termH)
                 "arboricx.abi.tree.v1"
-                Nothing
               ]
           manifestBytes = encodeManifest manifest
           manifestH = hashObject manifestDomain manifestBytes
@@ -2013,32 +2010,20 @@ contentStoreTests = testGroup "Content Store Tests"
               Nothing -> assertFailure "expected workspace module manifest"
               Just manifest -> map moduleExportName (moduleManifestExports manifest) @?= ["value"]
 
-  , testCase "Workspace modules: explicit !export with contract" $
-      withSystemTempDirectory "tricu-workspace-explicit-export" $ \dir -> do
+  , testCase "Workspace modules: contract annotations travel with exported definitions" $
+      withSystemTempDirectory "tricu-workspace-contract-export" $ \dir -> do
         let store = StorePath (dir </> "store")
             libPath = dir </> "util.tri"
             mainPath = dir </> "main.tri"
-        writeFile (dir </> "tricu.workspace") "module util = util.tri\n"
-        writeFile libPath "alwaysOk = (x : x)\n\naddOne x = x\n!export addOne : alwaysOk\n"
-        writeFile mainPath "!import \"util\" Util\n\nmain = Util.addOne 5\n"
+        cwd <- getCurrentDirectory
+        writeFile (dir </> "tricu.workspace") ("module base = \"" ++ cwd </> "lib/base.tri\"\nmodule util = \"" ++ dir </> "util.tri\"\n")
+        writeFile libPath "!import \"base\" !Local\n\nalwaysOk = (value rest : ok value rest)\n\nneverOk = (value rest : err \"nope\" rest)\n\nsafeId n@alwaysOk =@alwaysOk n\n\nbadId n@neverOk =@neverOk n\n"
+        writeFile mainPath "!import \"util\" Util\n\nmain = Util.safeId 5\n"
         env <- evaluateFileWithStore (Just store) mainPath
         result env @?= ofNumber 5
-        mAlias <- readAlias store ModuleAlias "util"
-        case mAlias of
-          Nothing -> assertFailure "expected workspace build to write util module alias"
-          Just ref -> do
-            mManifest <- getManifest store (objectRefHash ref)
-            case mManifest of
-              Nothing -> assertFailure "expected workspace module manifest"
-              Just manifest -> do
-                map moduleExportName (moduleManifestExports manifest) @?= ["addOne"]
-                case moduleManifestExports manifest of
-                  [ex] -> do
-                    assertBool "expected contract ref" (moduleExportContract ex /= Nothing)
-                    case moduleExportContract ex of
-                      Just cref -> objectRefKind cref @?= unDomain treeTermDomain
-                      Nothing -> assertFailure "expected contract ref"
-                  _ -> assertFailure "expected exactly one export"
+        writeFile mainPath "!import \"util\" Util\n\nmain = Util.badId 5\n"
+        envFail <- evaluateFileWithStore (Just store) mainPath
+        decodeResult (result envFail) @?= "\"nope\""
 
   , testCase "Module imports: resolve manifest exports from store" $
       withSystemTempDirectory "tricu-module-import" $ \dir -> do
@@ -2050,7 +2035,6 @@ contentStoreTests = testGroup "Content Store Tests"
                   "value"
                   (ObjectRef (unDomain treeTermDomain) root)
                   "arboricx.abi.tree.v1"
-                  Nothing
               ]
         root <- putTreeTerm store term
         manifestHash <- putManifest store (manifestFor root)
@@ -2083,7 +2067,7 @@ contentStoreTests = testGroup "Content Store Tests"
   , testCase "Module resolver diagnostics: missing tree term names export and hash" $ do
       let root = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
           manifest = ModuleManifest []
-            [ ModuleExport "value" (ObjectRef (unDomain treeTermDomain) root) "arboricx.abi.tree.v1" Nothing ]
+            [ ModuleExport "value" (ObjectRef (unDomain treeTermDomain) root) "arboricx.abi.tree.v1" ]
           resolver = ObjectResolver
             { resolverAlias = \kind name -> return $ if kind == ModuleAlias && name == "demo"
                 then Just (ObjectRef (unDomain manifestDomain) "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb")