Return the point of view of self on the keys only.

Note that self and keys are views on the same data; therefore any modification of one is visible on the other.

var x = new HashMap[String, Int]
x["four"] = 4
assert x.keys.has("four") == true
assert x.keys.has("five") == false

Property definitions

core $ MapRead :: keys
	# Return the point of view of self on the keys only.
	# Note that `self` and `keys` are views on the same data;
	# therefore any modification of one is visible on the other.
	#
	#     var x = new HashMap[String, Int]
	#     x["four"] = 4
	#     assert x.keys.has("four") == true
	#     assert x.keys.has("five") == false
	fun keys: Collection[K] is abstract
lib/core/collection/abstract_collection.nit:595,2--603,36

core $ Map :: keys
	redef fun keys: RemovableCollection[K] is abstract
lib/core/collection/abstract_collection.nit:765,2--51

counter $ Counter :: keys
	redef fun keys do return map.keys
lib/counter/counter.nit:70,2--34

core $ HashMap :: keys
	redef var keys: RemovableCollection[K] = new HashMapKeys[K, V](self) is lazy
lib/core/collection/hash_collection.nit:279,2--77

core $ ArrayMap :: keys
	redef var keys: RemovableCollection[K] = new ArrayMapKeys[K, E](self) is lazy
lib/core/collection/array.nit:716,2--78