@@ -548,7 +548,7 @@ This example illustrates the following aspects of `do` notation:
548Not illustrated here, but equally valid is the use of a binder on the left hand side of `<-` or `=`. For example:
548Not illustrated here, but equally valid is the use of a binder on the left hand side of `<-` or `=`. For example:
550```haskell
550```haskell
551−test arr = do
551+test arr = maybe do
552 (x:y:_) <- arr
552 (x:y:_) <- arr
553 return x + y
553 return x + y