diff options
| -rw-r--r-- | lib/stdlib/doc/src/sets.xml | 9 | ||||
| -rw-r--r-- | lib/stdlib/src/sets.erl | 8 |
2 files changed, 16 insertions, 1 deletions
diff --git a/lib/stdlib/doc/src/sets.xml b/lib/stdlib/doc/src/sets.xml index 4934bed365..1ed96ddc3f 100644 --- a/lib/stdlib/doc/src/sets.xml +++ b/lib/stdlib/doc/src/sets.xml @@ -140,6 +140,15 @@ </func> <func> + <name name="is_empty" arity="1"/> + <fsummary>Test for empty set.</fsummary> + <desc> + <p>Returns <c>true</c> if <c><anno>Set</anno></c> is an empty set, + otherwise <c>false</c>.</p> + </desc> + </func> + + <func> <name name="is_set" arity="1"/> <fsummary>Test for a <c>Set</c>.</fsummary> <desc> diff --git a/lib/stdlib/src/sets.erl b/lib/stdlib/src/sets.erl index c65a13b22e..ac0fc80526 100644 --- a/lib/stdlib/src/sets.erl +++ b/lib/stdlib/src/sets.erl @@ -37,7 +37,7 @@ -module(sets). %% Standard interface. --export([new/0,is_set/1,size/1,to_list/1,from_list/1]). +-export([new/0,is_set/1,size/1,is_empty/1,to_list/1,from_list/1]). -export([is_element/2,add_element/2,del_element/2]). -export([union/2,union/1,intersection/2,intersection/1]). -export([is_disjoint/2]). @@ -96,6 +96,12 @@ is_set(_) -> false. Set :: set(). size(S) -> S#set.size. +%% is_empty(Set) -> boolean(). +%% Return 'true' if Set is an empty set, otherwise 'false'. +-spec is_empty(Set) -> boolean() when + Set :: set(). +is_empty(S) -> S#set.size=:=0. + %% to_list(Set) -> [Elem]. %% Return the elements in Set as a list. -spec to_list(Set) -> List when |