1 files changed, 8 insertions, 23 deletions

diff --git a/lib/set.rb b/lib/set.rb
index 17775b07ea..9908aa6458 100644
--- a/lib/set.rb
+++ b/lib/set.rb
@@ -200,11 +200,7 @@ class Set
   # Equivalent to Set#flatten, but replaces the receiver with the
   # result in place.  Returns nil if no modifications were made.
   def flatten!
-    if detect { |e| e.is_a?(Set) }
-      replace(flatten())
-    else
-      nil
-    end
+    replace(flatten()) if any? { |e| e.is_a?(Set) }
   end
 
   # Returns true if the set contains the given object.
@@ -320,11 +316,7 @@ class Set
   # Adds the given object to the set and returns self.  If the
   # object is already in the set, returns nil.
   def add?(o)
-    if include?(o)
-      nil
-    else
-      add(o)
-    end
+    add(o) unless include?(o)
   end
 
   # Deletes the given object from the set and returns self.  Use +subtract+ to
@@ -337,11 +329,7 @@ class Set
   # Deletes the given object from the set and returns self.  If the
   # object is not in the set, returns nil.
   def delete?(o)
-    if include?(o)
-      delete(o)
-    else
-      nil
-    end
+    delete(o) if include?(o)
   end
 
   # Deletes every element of the set for which block evaluates to
@@ -367,9 +355,7 @@ class Set
   # Replaces the elements with ones returned by collect().
   def collect!
     block_given? or return enum_for(__method__)
-    set = self.class.new
-    each { |o| set << yield(o) }
-    replace(set)
+    replace(self.class.new(self) { |o| yield(o) })
   end
   alias map! collect!
 
@@ -379,7 +365,7 @@ class Set
     block or return enum_for(__method__)
     n = size
     delete_if(&block)
-    size == n ? nil : self
+    self if size != n
   end
 
   # Equivalent to Set#keep_if, but returns nil if no changes were
@@ -388,7 +374,7 @@ class Set
     block or return enum_for(__method__)
     n = size
     keep_if(&block)
-    size == n ? nil : self
+    self if size != n
   end
 
   # Merges the elements of the given enumerable object to the set and
@@ -439,7 +425,7 @@ class Set
   # ((set | enum) - (set & enum)).
   def ^(enum)
     n = Set.new(enum)
-    each { |o| if n.include?(o) then n.delete(o) else n.add(o) end }
+    each { |o| n.add(o) unless n.delete?(o) }
     n
   end
 
@@ -485,8 +471,7 @@ class Set
     h = {}
 
     each { |i|
-      x = yield(i)
-      (h[x] ||= self.class.new).add(i)
+      (h[yield(i)] ||= self.class.new).add(i)
     }
 
     h