fact(0) -> 1; %% Pattern matching for control-flow
fact(N) -> N * fact(N-1). %% Recursion to create loops
> example:fact(10). %% Interactive shell for fast iterations
3628800
> [{I, example:fact(I)} || I <- lists:seq(1,10)].
[{1, 1}, {2, 2}, {3, 6}, {4, 24}, {5, 120}, {6, 720},
{7, 5040}, {8, 40320}, {9, 362880}, {10, 3628800}]
函數式程式設計
> Fruits = ["banana","monkey","jungle"]. %% Immutable variables
["banana","monkey","jungle"]
> lists:map(fun string:uppercase/1, Fruits). %% Map values using stdlib functions
["BANANA","MONKEY","JUNGLE"]
%% Fold over lists using custom functions
> lists:foldl(fun(Str, Cnt) -> string:length(Str) + Cnt end, 0, Fruits).
18
高階函數
> Parent = self(). %% Get own process id
<0.376.0>
> Child = spawn(fun() -> receive go -> Parent ! lists:seq(1,100) end end).
<0.930.0>
> Child ! go. %% Send message to child
go
> receive Reply -> Reply end. %% Receive response from child
[1,2,3,4,5,6,7,8,9,10,11|...]
輕量級行程
-spec even(list(integer())) -> list(integer()).
even(Numbers) ->
mapreduce(Numbers, fun(Number) -> Number rem 2 == 0 end).
mapreduce(Numbers, Function) ->
Parent = self(),
[spawn(fun() -> Parent ! {Number, Function(Number)} end) || Number <- Numbers],
lists:flatten(
[receive {Number, true} -> Number; _ -> [] end || Number <- Numbers]).
平行 Map-Reduce 尋找偶數
%% Return factorial for N
fact(0) -> 1;
fact(N) -> N * fact(N-1).
> example:fact(10).
3628800
函數式程式設計
> Fruits = ["banana","monkey"].
["banana","monkey"]
> lists:map(
fun string:uppercase/1,
Fruits).
["BANANA","MONKEY"]
高階函數
> Me = self().
<0.376.0> %% Send msg using !
> spawn(fun() -> Me!lists:seq(1,10) end).
<0.930.0>
> receive Reply -> Reply end.
[1,2,3,4,5,6,7,8,9,10]
輕量級行程
-spec even(In) -> Out
when In :: list(integer()),
Out :: list(integer()).
even(Numbers) ->
[Number || Number <- Numbers,
Number rem 2 == 0].
尋找偶數
Erlang 是一種程式語言，用於建構具有高可用性要求的大規模可擴展軟即時系統。它的一些應用領域包括電信、銀行、電子商務、電腦電話和即時通訊。Erlang 的運行時系統內建支援並行處理、分散式和容錯。
Erlang 快速入門
