Index: src/OFArray.m
==================================================================
--- src/OFArray.m
+++ src/OFArray.m
@@ -411,12 +411,12 @@
 	append(ret, @selector(appendString:), [cArray[i] description]);
 
 	[pool release];
 
 	/*
-	 * Class swizzle the string to be immutable. We declared the return type
-	 * to be OFString*, so it can't be modified anyway. But not swizzling it
+	 * Class swizzle the array to be immutable. We declared the return type
+	 * to be OFArray*, so it can't be modified anyway. But not swizzling it
 	 * would create a real copy each time -[copy] is called.
 	 */
 	ret->isa = [OFString class];
 	return ret;
 }
@@ -493,12 +493,12 @@
 	[pool release];
 
 	[ret autorelease];
 
 	/*
-	 * Class swizzle the string to be immutable. We declared the return type
-	 * to be OFString*, so it can't be modified anyway. But not swizzling it
+	 * Class swizzle the array to be immutable. We declared the return type
+	 * to be OFArray*, so it can't be modified anyway. But not swizzling it
 	 * would create a real copy each time -[copy] is called.
 	 */
 	ret->isa = [OFString class];
 	return ret;
 }

Index: src/OFSet.h
==================================================================
--- src/OFSet.h
+++ src/OFSet.h
@@ -20,10 +20,15 @@
 #import "OFCollection.h"
 
 @class OFMutableDictionary;
 @class OFArray;
 
+#ifdef OF_HAVE_BLOCKS
+typedef void (^of_set_enumeration_block_t)(id object, BOOL *stop);
+typedef BOOL (^of_set_filter_block_t)(id object);
+#endif
+
 /**
  * \brief An unordered set of unique objects.
  */
 @interface OFSet: OFObject <OFCollection, OFCopying, OFMutableCopying>
 {
@@ -109,8 +114,26 @@
  *
  * \return Whether the receiver and the specified set have at least one object
  *	   in common
  */
 - (BOOL)intersectsSet: (OFSet*)set;
+
+#ifdef OF_HAVE_BLOCKS
+/**
+ * \brief Executes a block for each object.
+ *
+ * \param block The block to execute for each object
+ */
+- (void)enumerateObjectsUsingBlock: (of_set_enumeration_block_t)block;
+
+/**
+ * \brief Returns a new set, only containing the objects for which the block
+ *	  returns YES.
+ *
+ * \param block A block which determines if the object should be in the new set
+ * \return A new, autoreleased OFSet
+ */
+- (OFSet*)filteredSetUsingBlock: (of_set_filter_block_t)block;
+#endif
 @end
 
 #import "OFMutableSet.h"

Index: src/OFSet.m
==================================================================
--- src/OFSet.m
+++ src/OFSet.m
@@ -305,6 +305,35 @@
 		objects[i] = object;
 	}
 
 	return count;
 }
+
+#ifdef OF_HAVE_BLOCKS
+- (void)enumerateObjectsUsingBlock: (of_set_enumeration_block_t)block
+{
+	[dictionary enumerateKeysAndObjectsUsingBlock: ^ (id key, id object,
+	    BOOL *stop) {
+		block(key, stop);
+	}];
+}
+
+- (OFSet*)filteredSetUsingBlock: (of_set_filter_block_t)block
+{
+	OFMutableSet *ret = [OFMutableSet set];
+
+	[dictionary enumerateKeysAndObjectsUsingBlock: ^ (id key, id object,
+	    BOOL *stop) {
+		if (block(key))
+			[ret addObject: key];
+	}];
+
+	/*
+	 * Class swizzle the set to be immutable. We declared the return type
+	 * to be OFSet*, so it can't be modified anyway. But not swizzling it
+	 * would create a real copy each time -[copy] is called.
+	 */
+	ret->isa = [OFSet class];
+	return ret;
+}
+#endif
 @end