libraries/proposals/monad-fail.md

@@ -210,10 +210,11 @@ Both of those tell us the "real" desugaring as just another pattern we could rec
       (>>=) = <...bind impl...>
       -- NB: `return` defaults to `pure` since GHC 7.10
 
-      -- Monad(fail) will be removed in GHC 8.8+
+      -- Monad(fail) will be removed in GHC 8.8+; 
+      -- GHC may or may not ignore a definition in terms of MonadFail(fail) (decision pending)
       fail = Fail.fail
 
-    instance MonadFail Foo where
+    instance Fail.MonadFail Foo where
       fail = <...fail implementation...>
     ```
   1. Change your pattern to be irrefutable
@@ -221,17 +222,17 @@ Both of those tell us the "real" desugaring as just another pattern we could rec
 
     ```
     do Left e <- foobar
-      stuff
+       stuff
     ```
 
     becomes
 
     ```
     do x <- foobar
-      e <- case x of
+       e <- case x of
           Left e' -> e'
           Right r -> error "Pattern match failed" -- Boooo
-      stuff
+       stuff
     ```
 
     The point is you'll have to do your dirty laundry yourself now if you have a value that *you* know will always match, and if you don't handle the other patterns you'll get incompleteness warnings, and the compiler won't silently eat those for you.