fix issue with try in parser, improve parse error message

src/Lib/Parser.newt

@@ -442,9 +442,11 @@ quantity = fromMaybe Many <$> optional (Zero <$ keyword "0")
 ebind : Parser Telescope
 ebind = do
   -- don't commit until we see the ":"
+  (quant, names) <- try $ do
     symbol "("
     quant <- quantity
-  names <- try (some (addPos varname) <* symbol ":")
+    names <- some (addPos varname) <* symbol ":"
+    pure (quant,names)
   ty <- typeExpr
   symbol ")"
   pure $ map (makeBind quant ty) names
@@ -662,8 +664,10 @@ parseNorm = DCheck <$> getPos <* keyword "#check" <*> typeExpr <* keyword ":" <*
 
 parseDecl : Parser Decl
 parseDecl = parseMixfix <|> parsePType <|> parsePFunc
-  <|> parseNorm <|> parseData <|> parseShortData <|> parseSig <|> parseDef
+  <|> parseNorm <|> parseData <|> parseShortData
   <|> parseClass <|> parseInstance <|> parseRecord
+  -- We'll put the backtracing stuff last, but there is a commit issue in parseDef
+  <|> parseSig <|> parseDef
 
 
 

src/Lib/Parser/Impl.newt

@@ -63,7 +63,7 @@ partialParse fn pa ops toks = case runP pa emptyBounds toks False ops (emptyFC'
 
 try : ∀ a. Parser a -> Parser a
 try (P pa) = P $ \last toks com ops col => case pa last toks com ops col of
-  (Fail x err last toks com ops) => Fail x err last toks False ops
+  (Fail x err last toks _ ops) => Fail x err last toks com ops
   res => res
 
 
@@ -71,8 +71,8 @@ fail : ∀ a. String -> Parser a
 fail msg = P $ \last toks com ops col => Fail False (perror col.file toks msg) last toks com ops
 
 
-fatal : ∀ a. String -> Parser a
+-- fatal : ∀ a. String -> Parser a
-fatal msg = P $ \last toks com ops col => Fail True (perror col.file toks msg) last toks com ops
+-- fatal msg = P $ \last toks com ops col => Fail True (perror col.file toks msg) last toks com ops
 
 
 getOps : Parser (Operators)
@@ -85,7 +85,7 @@ addOp nm prec fix = P $ \ last toks com ops col =>
   case parts of
     "" :: key :: rule => OK MkUnit last toks com (updateMap key (MkOp nm prec fix False rule) ops)
     key :: rule => OK MkUnit last toks com (updateMap key (MkOp nm prec fix True rule) ops)
-    Nil => Fail True (perror col.file toks "Internal error parsing mixfix") last toks com ops
+    Nil => Fail False (perror col.file toks "Internal error parsing mixfix") last toks com ops
 
 instance Functor Parser where
   map f (P pa) = P $ \ last toks com ops col => map f (pa last toks com ops col)
@@ -211,7 +211,7 @@ token' : Kind -> Parser String
 token' k = satisfy (\t => t.val.kind == k) "Expected a \{show k} token"
 
 keyword' : String -> Parser Unit
-keyword' kw = ignore $ satisfy (\t => t.val.text == kw && (t.val.kind == Keyword || t.val.kind == Symbol || t.val.kind == Number)) "Expected \{kw}"
+keyword' kw = ignore $ satisfy (\t => t.val.text == kw && (t.val.kind == Keyword || t.val.kind == Symbol || t.val.kind == Number)) "Expected '\{kw}'"
 
 -- expect indented token of given kind
 

tests/ErrMsg.newt

@@ -0,0 +1,14 @@
+module ErrMsg
+
+import Prelude
+
+infixl 5 _$$_
+
+_$$_ : Nat → (Nat → Nat) → Nat
+a $$ b = a + b a
+
+-- Say something other than expected record
+-- Why do we get there? shouldn't the progress made by parseDef short circuit the <|>?
+blah : Nat → Nat
+blah x = x $$ $ \ y => y
+

tests/ErrMsg.newt.fail

@@ -0,0 +1,6 @@
+*** Process tests/ErrMsg.newt
+module Prelude
+module ErrMsg
+ERROR at tests/ErrMsg.newt:13:15--13:16: trailing operator
+
+Compile failed