fixes #4233 - term declarations should not allow hashes in term names

CONTRIBUTORS.markdown

@@ -76,3 +76,4 @@ The format for this list: name, GitHub handle
 * Mario Bašić (@mabasic)
 * Chris Krycho (@chriskrycho)
 * Hatim Khambati (@hatimkhambati26)
+* Kyle Goetz (@kylegoetz)

parser-typechecker/src/Unison/Syntax/TermParser.hs

@@ -985,7 +985,7 @@ infixAppOrBooleanOp = chainl1 term4 (or <|> and <|> infixApp)
 typedecl :: (Monad m, Var v) => P v m (L.Token v, Type v Ann)
 typedecl =
   (,)
-    <$> P.try (prefixDefinitionName <* reserved ":")
+    <$> P.try (prefixTermName <* reserved ":")
     <*> TypeParser.valueType
     <* semi
 
@@ -1053,8 +1053,8 @@ binding = label "binding" do
         arg2 <- prefixDefinitionName
         pure (ann arg1, op, [arg1, arg2])
   let prefixLhs = do
-        v <- prefixDefinitionName
-        vs <- many prefixDefinitionName
+        v <- prefixTermName
+        vs <- many prefixTermName
         pure (ann v, v, vs)
   let lhs :: P v m (Ann, L.Token v, [L.Token v])
       lhs = infixLhs <|> prefixLhs

unison-syntax/src/Unison/Syntax/Parser.hs

@@ -297,6 +297,19 @@ prefixDefinitionName :: (Var v) => P v m (L.Token v)
 prefixDefinitionName =
   wordyDefinitionName <|> parenthesize symbolyDefinitionName
 
+-- Parse a prefix identifier e.g. Foo or (+), rejecting any hash
+-- This is useful for term declarations, where type signatures and term names should not have hashes.
+prefixTermName :: (Var v) => P v (L.Token v)
+prefixTermName = wordyTermName <|> parenthesize symbolyTermName
+  where
+    wordyTermName = queryToken $ \case
+      L.WordyId s Nothing -> Just $ Var.nameds s
+      L.Blank s -> Just $ Var.nameds ("_" <> s)
+      _ -> Nothing
+    symbolyTermName = queryToken $ \case
+      L.SymbolyId s Nothing -> Just $ Var.nameds s
+      _ -> Nothing
+
 -- Parse a wordy identifier e.g. Foo, discarding any hash
 wordyDefinitionName :: (Var v) => P v m (L.Token v)
 wordyDefinitionName = queryToken $ \case