[tests] add test and error for missing function clause

src/MiniJuvix/Syntax/Concrete/Scoped/Error/Pretty/Base.hs

@@ -53,6 +53,14 @@ infixErrorAux kind pp =
   "Error while resolving infixities in the" <+> kind <> ":" <> line
     <> indent' (highlight pp)
 
+instance PrettyError LacksFunctionClause where
+  ppError LacksFunctionClause {..} =
+     pretty loc <> line <>
+     "There is a type signature no function clause:" <> line
+     <> indent' (highlight (ppCode _lacksFunctionClause))
+    where
+    loc = getLoc $ _sigName _lacksFunctionClause
+
 instance PrettyError LacksTypeSig where
   ppError LacksTypeSig {..} =
      pretty loc <> line <>

src/MiniJuvix/Syntax/Concrete/Scoped/Error/Types.hs

@@ -33,6 +33,12 @@ newtype LacksTypeSig = LacksTypeSig {
   }
  deriving stock (Show)
 
+-- | type signature without a function clause
+newtype LacksFunctionClause = LacksFunctionClause {
+  _lacksFunctionClause :: TypeSignature 'Scoped
+  }
+ deriving stock (Show)
+
 newtype ImportCycle = ImportCycle {
   -- | If we have [a, b, c] it means that a import b imports c imports a.
   _importCycleImports :: NonEmpty (Import 'Parsed)

src/MiniJuvix/Syntax/Concrete/Scoped/Scoper.hs

@@ -495,6 +495,7 @@ checkModuleBody :: forall r.
 checkModuleBody body = do
   body' <- mapM checkStatement body
   checkOrphanFixities
+  checkClausesExist body'
   exported <- get >>= exportScope
   return (exported, body')
 
@@ -532,7 +533,14 @@ checkLocalModule Module {..} = do
     inheritEntry :: SymbolEntry -> SymbolEntry
     inheritEntry = over S.nameWhyInScope S.BecauseInherited
 
-checkOrphanFixities :: forall r .Members '[Error ScopeError, State Scope] r => Sem r ()
+checkClausesExist :: forall r. Members '[Error ScopeError, State Scope] r => [Statement 'Scoped] -> Sem r ()
+checkClausesExist ss = whenJust msig (throw . ErrLacksFunctionClause . LacksFunctionClause)
+  where
+  msig = listToMaybe [ ts | StatementTypeSignature ts <- ss,
+          null [ c | StatementFunctionClause c <- ss ,
+                 c ^. clauseOwnerFunction == ts ^. sigName]]
+
+checkOrphanFixities :: forall r. Members '[Error ScopeError, State Scope] r => Sem r ()
 checkOrphanFixities = do
   path <- gets _scopePath
   declared <- gets _scopeFixities
@@ -542,7 +550,6 @@ checkOrphanFixities = do
     [] -> return ()
     (x : _) -> throw (ErrUnusedOperatorDef (UnusedOperatorDef x))
 
-
 symbolInfoSingle :: SymbolEntry -> SymbolInfo
 symbolInfoSingle p = SymbolInfo $ HashMap.singleton (S._nameDefinedIn p) p
 

test/Scope/Negative.hs

@@ -118,4 +118,11 @@ tests = [
       case er of
         ErrAmbiguousSym {} -> Nothing
         _ -> wrongError
+  ,  NegTest "Lacks function clause"
+    "."
+   "LacksFunctionClause.mjuvix" $ \er ->
+      case er of
+        ErrLacksFunctionClause {} -> Nothing
+        _ -> wrongError
+
   ]

tests/negative/LacksFunctionClause.mjuvix

@@ -0,0 +1,4 @@
+module LacksFunctionClause;
+
+  id : Type → Type → Type;
+end;