Fix #227

src/plfa/part1/Lists.lagda.md

@@ -115,12 +115,11 @@ _++_ : ∀ {A : Set} → List A → List A → List A
 []       ++ ys  =  ys
 (x ∷ xs) ++ ys  =  x ∷ (xs ++ ys)
 ```
-The type `A` is an implicit argument to append, making it a
-_polymorphic_ function (one that can be used at many types).  The
-empty list appended to another list yields the other list.  A
-non-empty list appended to another list yields a list with head the
-same as the head of the first list and tail the same as the tail of
-the first list appended to the second list.
+The type `A` is an implicit argument to append, making it a _polymorphic_
+function (one that can be used at many types). A list appended to the empty list
+yields the list itself. A list appended to a non-empty list yields a list with
+the head the same as the head of the non-empty list, and a tail the same as the
+other list appended to tail of the non-empty list.
 
 Here is an example, showing how to compute the result
 of appending two lists: