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Add 'compose/1', 'compose/2' functions

This commit is contained in:
Feng Lee 2020-01-13 21:00:40 +08:00
parent 1c41302dad
commit 2ba624ac31
1 changed files with 11 additions and 0 deletions
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11
src/emqx_misc.erl
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@ -23,6 +23,8 @@
-export([ merge_opts/2 -export([ merge_opts/2
, maybe_apply/2 , maybe_apply/2
, compose/1
, compose/2
, run_fold/3 , run_fold/3
, pipeline/3 , pipeline/3
, start_timer/2 , start_timer/2
@ -61,6 +63,15 @@ maybe_apply(_Fun, undefined) ->
maybe_apply(Fun, Arg) when is_function(Fun) -> maybe_apply(Fun, Arg) when is_function(Fun) ->
erlang:apply(Fun, [Arg]). erlang:apply(Fun, [Arg]).
-spec(compose(list(F)) -> G when F :: fun((any()) -> any()),
G :: fun((any()) -> any())).
compose([F|More]) -> compose(F, More).
-spec(compose(fun((X) -> Y), fun((Y) -> Z)) -> fun((X) -> Z)).
compose(F, G) when is_function(G) -> fun(X) -> G(F(X)) end;
compose(F, [G]) -> compose(F, G);
compose(F, [G|More]) -> compose(compose(F, G), More).
%% @doc RunFold %% @doc RunFold
run_fold([], Acc, _State) -> run_fold([], Acc, _State) ->
Acc; Acc;