Add parsers

examples/parser.hs

@@ -1,16 +1,29 @@
+data Tuple a b = Tuple a b
 data Result a = OK a String | Error String
 data Parser a = Parser (String -> Result a)
 parseBool =
   Parser
     (\string ->
        case take 4 string of
-         "True" -> OK True (drop 4 string)
+         "True" ->
+           case drop 4 string of
+             !rest -> OK True rest
          _ ->
            case take 5 string of
-             "False" -> OK False (drop 5 string)
+             "False" ->
+               case drop 5 string of
+                 !rest -> OK False rest
              _ -> Error (append "Expected a bool, but got: " string))
 runParser =
   \p s ->
     case p of
       Parser f -> f s
-main = runParser parseBool "TrueFalse"
+bind =
+  \m f ->
+    Parser
+      (\s ->
+         case runParser m s of
+           OK a rest -> runParser (f a) rest
+           Error err -> Error err)
+pure = \a -> Parser (OK a)
+main = runParser (bind parseBool (\x -> bind parseBool (\y -> pure (Tuple x y)))) "TrueFalse"

src/Duet/Errors.hs

@@ -101,7 +101,7 @@ displayRenamerException specialTypes =
           IdentifierNotInVarScope scope name label ->
             "Not in variable scope " ++
             curlyQuotes (printit defaultPrint name) ++
-            " (AST tree label: "++show label ++")"++
+            -- " (AST tree label: "++show label ++")"++
             "\n" ++
             "Nearest names in scope:\n\n" ++
             intercalate