Make <?> infixr and update prec to 2 (#163)

* Make <?> infixr and update prec to 2

* Add changelog entry

Author: JordanMartinez

CHANGELOG.md

@@ -7,6 +7,11 @@ Notable changes to this project are documented in this file. The format is based
 Breaking changes:
 - Update project and deps to PureScript v0.15.0 (#160 by @JordanMartinez)
 - Drop deprecated `MonadZero` instance (#160 by @JordanMartinez)
+- Make `<?>` right-associative and increase prec from 3 to 2 (#163 by @JordanMartinez)
+
+  `<|>` was made right associative. `<?>` was likewise changed to prevent a 
+  possible error and its precedence was increased so that `foo <|> bar <?> "err msg"`
+  works without parenthesis around `"err msg"` part.
 
 New features:
 

src/Text/Parsing/Parser/Combinators.purs

@@ -119,7 +119,7 @@ import Text.Parsing.Parser (ParseError(..), ParseState(..), ParserT(..), fail)
 withErrorMessage :: forall m s a. Monad m => ParserT s m a -> String -> ParserT s m a
 withErrorMessage p msg = p <|> fail ("Expected " <> msg)
 
-infixl 3 withErrorMessage as <?>
+infixr 2 withErrorMessage as <?>
 
 -- | Provide an error message in the case of failure, but lazily. This is handy
 -- | in cases where constructing the error message is expensive, so it's