[m-rev.] diff: fix documentation of map.union

[Julien Fischer]

Branches: master, 13.05

----------

Fix the documentation of map.union/4.

library/map.m:
 	Add a missing word.

 	Refer to the higher-order argument as a closure rather than
 	a predicate since the description covers both the function
 	and predicate versions of map.union.

Julien

diff --git a/library/map.m b/library/map.m
index 40adf9d..b15a6fe 100644
--- a/library/map.m
+++ b/library/map.m
@@ -663,11 +663,11 @@
      %
  :- func map.common_subset(map(K, V), map(K, V)) = map(K, V).

-    % Given two maps M1 and M2, create a third map M3 that all the keys
-    % that occur in either M1 and M2. For keys that occur in both M1
+    % Given two maps M1 and M2, create a third map M3 that contains all
+    % the keys that occur in either M1 and M2. For keys that occur in both M1
      % and M2, compute the value in the final map by applying the supplied
-    % predicate to the values associated with the key in M1 and M2.
-    % Fail if and only if this predicate fails on the values associated
+    % closure to the values associated with the key in M1 and M2.
+    % Fail if and only if this closure fails on the values associated
      % with some common key.
      %
  :- func map.union(func(V, V) = V, map(K, V), map(K, V)) = map(K, V).