Why Erlang? -Partial

Preface

Hope it is not a pitfall. We plan to adopt a structured latency strategy, which will be written before the dead line (July is the planned Erlang month.

 

Perfect plan

The advantages or interesting aspects of Erlang over Java are as follows: imperative language v. S. Functional language, thread abstraction and architecture, and distributed programming support.

 

Cruel and ugly practices

Example 1 fast sorting

JAVA Implementation (data structure and algorithm-sort algorithm-partial http://www.cnblogs.com/zhoujiagen/p/3690243.html)

Erlang implementation

 1 -module(lib_misc). 2  3 %% API 4 -export([for/3, qsort/1]). 5  6 %%%=================================================================== 7 %%% API 8 %%%=================================================================== 9 % simulate ‘for‘ syntax contructor - inner DSL 10 for(Max, Max, F) ->11     [F(Max)];12 for(I, Max, F) ->13     [F(I)|for(I+1, Max, F)].14 15 % quick sort16 qsort([]) ->17     [];18 qsort([Pivot|T]) ->19     qsort([X || X<-T, X < Pivot])20     ++ [Pivot] ++21     qsort([X || X<-T, X > Pivot]).22 23 24 %%--------------------------------------------------------------------25 %% @doc26 %% @spec27 %% @end28 %%--------------------------------------------------------------------29 30 %%%===================================================================31 %%% Internal functions32 %%%===================================================================

View code

The brain hole is wide open, and the language is a programmer's weapon. It is inevitable that the language with the ability to express itself close to the essence of the problem is concise.

 

Example 2 Inheritance

Calculate the area of the image, as long as the area of the rectangle, square, and circle is calculated.

The orthodox oo programmers (including me) need four classes for Java implementation.

Erlang implementation

 1 %%%------------------------------------------------------------------- 2 %%% @author  <[email protected]> 3 %%% @copyright (C) 2014,  4 %%% @doc 5 %%% 6 %%% @end 7 %%% Created :  6 Jul 2014 by  <[email protected]> 8 %%%------------------------------------------------------------------- 9 -module(geometry).10 11 %% API12 -export([area/1]).13 14 %%%===================================================================15 %%% API16 %%%===================================================================17 area({rectangle, Width, Height}) ->18     Width * Height;19 area({square, Side}) ->20     Side * Side;21 area({circle, Radius}) ->22     3.14159 * Radius * Radius.23 24 %%--------------------------------------------------------------------25 %% @doc26 %% @spec27 %% @end28 %%--------------------------------------------------------------------29 30 %%%===================================================================31 %%% Internal functions32 %%%===================================================================

View code

Well, it seems that Java implementation with enumeration can be very concise.

In another example, although I use python, I dare say that the database access code written by python is 80% shorter than the Java JDBC access code.

I just want to express that although a route passes through Rome, most people prefer a short journey.