Erlang PostgreSQL client library
http://bitbucket.org/will/epgsql/overview/
http://glozer.net/src/epgsql_pool/(http://www.erlangatwork.com/2009/01/erlang-and-postgresql-redux.html)
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(http://www.erlangatwork.com/2009/01/erlang-and-postgresql-redux.html)
Z
พิมพ์ตัว Z ออกมาเฉยๆ
-module(zeez2).
-export([main/1]).
main([A]) ->
L = list_to_integer(atom_to_list(A)),
zeez( true ,L, L).
zeez(true, 0, N) ->
io:format("~p~n", [zeez(z, N)]),
init:stop();
zeez(false, M, N) ->
io:format("~p~n", [zeez(space, M)]),
zeez(M-1 rem N =:= 0, M-1, N );
zeez(true, M, N) ->
io:format("~p~n", [zeez(z, M)]),
zeez(M-1 rem N =:= 0, M-1 , N ).
zeez(space, 0) ->
"Z";
zeez(space, N) ->
"-" ++ zeez(space, N-1);
zeez(z,0) ->
"Z";
zeez(z, N) ->
"Z" ++ zeez(z, N-1).
wk# erlc zeez2.erl wk# erl -noshell -s zeez2 main 10 "ZZZZZZZZZZZ" "---------Z" "--------Z" "-------Z" "------Z" "-----Z" "----Z" "---Z" "--Z" "-Z" "ZZZZZZZZZZZ" wk#
วันทั้งหมดในปีนี้
พิมพ์วันทั้งหมดที่มีในปีนี้
-module(cal).
-export([main/0]).
main() ->
StartSec = calendar:datetime_to_gregorian_seconds({{2009,1,1},{0,0,0}}),
EndSec = calendar:datetime_to_gregorian_seconds({{2009,12,31},{0,0,0}}),
run_calendar(StartSec,EndSec).
run_calendar(CurSec, EndSec) ->
{Date,_Time} = calendar:gregorian_seconds_to_datetime(CurSec),
io:format("~p~n", [Date]),
NewSec = CurSec + 60*60*24,
if NewSec =< EndSec -> init:stop() end,
run_calendar(NewSec, EndSec).
wk# erlc cal.erl
wk# erl -noshell -s cal main
{2009,1,1}
{2009,1,2}
{2009,1,3}
---
{2009,12,29}
{2009,12,30}
{2009,12,31}
Erlang R13B03 released
Some highlights:
NIFs, write your own functions in C
Builds and runs on Windows 7
dialyzer can warn for some race conditions, and has a wx gui
The -on_load() directive can be used to run a function when a module is loaded.
Emacs erlang-mode improvements.
Erlang User Conference 2009 Materials
Materials from the Erlang User Conference 2009 and Tutorials Workshop at the EUC2009 are now available on our website:
- The presentation slides from the EUC2009 are available (http://www.erlang-factory.com/conference/ErlangUserConference2009/talks)- The tutorial slides can be found (http://www.erlang-factory.com/conference/testingtutorialworkshop/talks)
- The photos taken at the EUC2009 are (http://www.erlang-factory.com/conference/ErlangUserConference2009#euc2009)
- The photos taken at the Tutorials Workshop are (http://www.erlang-factory.com/conference/testingtutorialworkshop#photos)If you want to see more photos from the EUC2009 and previous Erlang User Conferences, they are all available on Flickr: http://www.flickr.com/photos/erlang-consulting/
Project Euler ข้อ 9
คำถาม
A Pythagorean triplet is a set of three natural numbers, a < b < c, for which,
a^2 + b^2 = c^2For example, 3^2 + 4^2 = 9 + 16 = 25 = 52.There exists exactly one Pythagorean triplet for which a + b + c = 1000.
Find the product abcคำตอบ
a^2 + b^2 = c^2For example, 3^2 + 4^2 = 9 + 16 = 25 = 52.There exists exactly one Pythagorean triplet for which a + b + c = 1000.
Find the product abcคำตอบ
wk# erlc pythag2.erl
wk# erl -noshell -s pythag2 main 1000
Pythag 1000 = [{200,375,425}]
Product [{200,375,425}] = 31875000
หา Pythagorean ด้วย Erlang
1> Pythag = fun(N) -> [ {A,B,C} ||
A <- lists:seq(1,N),
B <- lists:seq(1,N),
C <- lists:seq(1,N),
A= Pythag(100).
[{3,4,5}, {5,12,13}, {6,8,10},
{7,24,25},{8,15,17}, {9,12,15},
{9,40,41}, {10,24,26}, {12,16,20},
{12,35,37}, {15,20,25}, {15,36,39},
{16,30,34}, {18,24,30}, {20,21,29},
{21,28,35}, {24,32,40}]
สร้าง Anagram ด้วย Erlang
ฟังก์ชันสำหรับสร้าง Anagram
Foo = fun(X) -> Fun = fun([],F) -> [[]]; (L,F) -> [[H|T] || H <- L, T <- F(L--[H],F)] end, Fun(X, Fun) end.
ทดสอบ
wearetherock# erl
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> Foo = fun(X) -> Fun = fun([],F) -> [[]]; (L,F) -> [[H|T] || H <- L, T <- F(L--[H],F)] end, Fun(X, Fun) end.
#Fun<erl_eval.6.13229925>
2> Foo("mary").
["mary","mayr","mray","mrya","myar","myra","amry","amyr",
"army","arym","aymr","ayrm","rmay","rmya","ramy","raym",
"ryma","ryam","ymar","ymra","yamr","yarm","yrma","yram"]
3> Foo("cat").
["cat","cta","act","atc","tca","tac"]
4> Foo("orchestra").
["orchestra","orchestar","orchesrta","orchesrat",
"orchesatr","orchesart","orchetsra","orchetsar","orchetrsa",
"orchetras","orchetasr","orchetars","orchersta","orchersat",
"orchertsa","orchertas","orcherast","orcherats","orcheastr",
"orcheasrt","orcheatsr","orcheatrs","orchearst","orchearts",
"orchsetra","orchsetar","orchserta","orchserat",
[...]|...]
