The example of Bidirectional Pattern synonyms doesn't compile in new versions of GHC, plus there was a note to rewrite the example. I've rewritten it to use ViewPatterns.

pattern-synonyms.md

@@ -303,15 +303,13 @@ This is the rationale for the most complicated synonyms, the bidirectional ones.
 where *cfunlhs* is like *funlhs*, except that the functions symbol is a *conid* instead of a *varid*.
 
 
-Example:
+Example, using [ViewPatterns](view-patterns):
 
 ```wiki
-   pattern Succ n <- n1 | let n = n1-1, n >= 0 where
+   pattern Succ n <- ((\x -> (x-1) <$ guard (x > 0)) -> Just n) where
       Succ n = n + 1
 ```
 
-**TODO**: Rewrite this example to not use [ViewPatternsAlternative](view-patterns-alternative)
-
 
 The first part as is before and describes the expansion of the synonym in patterns. The second part describes the expansion in expressions.