{"generator":"Jekyll","link":[{"@attributes":{"href":"https:\/\/etern.github.io\/feed.xml","rel":"self","type":"application\/atom+xml"}},{"@attributes":{"href":"https:\/\/etern.github.io\/","rel":"alternate","type":"text\/html"}}],"updated":"2022-04-19T09:11:07+00:00","id":"https:\/\/etern.github.io\/feed.xml","title":"Blog","subtitle":"\u60df\u6c5f\u4e0a\u4e4b\u6e05\u98ce\uff0c\u4e0e\u5c71\u95f4\u4e4b\u660e\u6708\uff0c\u8033\u5f97\u4e4b\u800c\u4e3a\u58f0\uff0c\u76ee\u9047\u4e4b\u800c\u6210\u8272\n","entry":[{"title":"quick sort","link":{"@attributes":{"href":"https:\/\/etern.github.io\/2022\/04\/19\/quick-sort.html","rel":"alternate","type":"text\/html","title":"quick sort"}},"published":"2022-04-19T08:50:05+00:00","updated":"2022-04-19T08:50:05+00:00","id":"https:\/\/etern.github.io\/2022\/04\/19\/quick-sort","content":"

When haskellers say they can implement quick sort in just 2 loc:<\/p>\n\n

qsort<\/span> []<\/span> =<\/span> []<\/span>\nqsort<\/span> (<\/span>x<\/span>:<\/span>xs<\/span>)<\/span> =<\/span> qsort<\/span> [<\/span>a<\/span> |<\/span> a<\/span> <-<\/span> xs<\/span>,<\/span> a<\/span> <=<\/span> x<\/span>]<\/span> ++<\/span> [<\/span>x<\/span>]<\/span> ++<\/span> qsort<\/span> [<\/span>a<\/span> |<\/span> a<\/span> <-<\/span> xs<\/span>,<\/span> a<\/span> ><\/span> x<\/span>]<\/span>\n<\/code><\/pre><\/div><\/div>\n\n
Pythoner smiles:<\/p>\n\n
def<\/span> qsort<\/span>(<\/span>x<\/span>=<\/span>[],<\/span> *<\/span>xs<\/span>):<\/span>\n\treturn<\/span> x<\/span> and<\/span> (<\/span>qsort<\/span>(<\/span>*<\/span>[<\/span>a<\/span> for<\/span> a<\/span> in<\/span> xs<\/span> if<\/span> a<\/span> <<\/span> x<\/span>])<\/span> +<\/span> [<\/span>x<\/span>]<\/span> +<\/span> qsort<\/span>(<\/span>*<\/span>[<\/span>b<\/span> for<\/span> b<\/span> in<\/span> xs<\/span> if<\/span> b<\/span> >=<\/span>x<\/span>]))<\/span>\n# (x != 0) call with arg destructuring: qsort(*[3, 1, 2])\n<\/span><\/code><\/pre><\/div><\/div>\n\n
For linked list sort, we don\u2019t have to do inplace swaping, this is\nalright. Argument destructuring is used to imitate haskell pattern\nmatching, and here is a real pattern matching version (py3.10):<\/p>\n\n
def<\/span> qsort<\/span>(<\/span>xs<\/span>):<\/span>\n    match<\/span> xs<\/span>:<\/span>\n        case<\/span> []:<\/span>\n            return<\/span> []<\/span>\n        case<\/span> [<\/span>x<\/span>,<\/span> *<\/span>rest<\/span>]:<\/span>\n            return<\/span> qsort<\/span>([<\/span>a<\/span> for<\/span> a<\/span> in<\/span> rest<\/span> if<\/span> a<\/span> <<\/span> x<\/span>])<\/span> +<\/span> [<\/span>x<\/span>]<\/span> +<\/span> qsort<\/span>([<\/span>b<\/span> for<\/span> b<\/span> in<\/span> rest<\/span> if<\/span> b<\/span> >=<\/span>x<\/span>])<\/span>\n<\/code><\/pre><\/div><\/div>\n\n
Still concise, power of multi paradigm language!<\/p>","author":{"name":{}},"summary":"When haskellers say they can implement quick sort in just 2 loc:"},{"title":"Add toggle switch for everything to your Windows desktop","link":{"@attributes":{"href":"https:\/\/etern.github.io\/2022\/02\/16\/add-toggle-switch-to-your-windows-desktop.html","rel":"alternate","type":"text\/html","title":"Add toggle switch for everything to your Windows desktop"}},"published":"2022-02-16T10:56:55+00:00","updated":"2022-02-16T10:56:55+00:00","id":"https:\/\/etern.github.io\/2022\/02\/16\/add-toggle-switch-to-your-windows-desktop","content":"
The idea is simple:<\/p>\n
    \n  
  1. With powershell script, you can do almost everything on Windows,\nfor instance, start\/stop a service:\n    
    Start-Service<\/span> <\/span>-Name<\/span> <\/span>FortiSslvpnDaemon<\/span>\n<\/span>Stop-Service<\/span> <\/span>-Name<\/span> <\/span>FortiSslvpnDaemon<\/span>\n<\/span><\/code><\/pre><\/div>    <\/div>\n  <\/li>\n  
  2. Create a desktop shortcut for that script<\/li>\n  
  3. You can change the look of shortcut on clicking!! That makes a\nswitch with visual state<\/li>\n<\/ol>\n\n
    Here an example powershell script that start\/stop a service:<\/p>\n\n
    $shortCutFile<\/span> <\/span>=<\/span> <\/span>\"C:\\Users\\xxx\\Desktop\\ToggleFortiVPNDaemon.lnk\"<\/span>\n<\/span>$svcName<\/span> <\/span>=<\/span> <\/span>\"FortiSslvpnDaemon\"<\/span>\n\n<\/span>function<\/span> <\/span>Change-Shortcut-Icon<\/span>(<\/span>$scFile<\/span>,<\/span> <\/span>$iconNo<\/span>)<\/span> <\/span>{<\/span>\n    <\/span>$WScriptShell<\/span> <\/span>=<\/span> <\/span>New-Object<\/span> <\/span>-ComObject<\/span> <\/span>WScript.Shell<\/span>\n    <\/span>$shortcut<\/span> <\/span>=<\/span> <\/span>$WScriptShell<\/span>.<\/span>CreateShortcut<\/span>(<\/span>$scFile<\/span>)<\/span>\n    <\/span>$shortcut<\/span>.<\/span>IconLocation<\/span> <\/span>=<\/span> <\/span>\"C:\\Windows\\System32\\imageres.dll, <\/span>$iconNo<\/span>\"<\/span>\n    <\/span>$shortcut<\/span>.<\/span>Save<\/span>()<\/span>\n<\/span>}<\/span>\n\n<\/span>$svc<\/span> <\/span>=<\/span> <\/span>Get-Service<\/span> <\/span>-Name<\/span> <\/span>$svcName<\/span>\n<\/span>if<\/span> <\/span>(<\/span>$svc<\/span>.<\/span>Status<\/span> <\/span>-eq<\/span> <\/span>'Running'<\/span>)<\/span> <\/span>{<\/span>\n    <\/span>Stop-Service<\/span> <\/span>-Name<\/span> <\/span>$svcName<\/span>\n    <\/span>echo<\/span> <\/span>\"stoped\"<\/span>\n    <\/span>Change-Shortcut-Icon<\/span> <\/span>$shortCutFile<\/span> <\/span>26<\/span>\n<\/span>}<\/span> <\/span>elseif<\/span> <\/span>(<\/span>$svc<\/span>.<\/span>Status<\/span> <\/span>-eq<\/span> <\/span>'Stopped'<\/span>)<\/span> <\/span>{<\/span>\n    <\/span>Start-Service<\/span> <\/span>-Name<\/span> <\/span>$svcName<\/span>\n    <\/span>echo<\/span> <\/span>\"started\"<\/span>\n    <\/span>Change-Shortcut-Icon<\/span> <\/span>$shortCutFile<\/span> <\/span>28<\/span>\n<\/span>}<\/span>\n<\/span><\/code><\/pre><\/div><\/div>\n\n
    Store this script as ToggleFortiVPNDaemon.ps1<\/code> somewhere like\nC:\/myscripts<\/code>, and create Desktop shortcut for it, rename the\nshortcut to ToggleFortiVPNDaemon<\/code>.<\/p>\n\n
    To run the shortcut as Admin (required by service commands), open\nproperty dialog of the shortcut, in the Target<\/code> field, add\npowershell<\/code> before the script name, and click Advanced<\/code> button,\ncheck the Run as Admin<\/code>.<\/p>\n\n
    Now, double click the Desktop shortcut, after a confirmation for admin\npermission, the service is under control.<\/p>\n\n
    The shortcut icon changes as you click, to reflect the service state,\nand that\u2019s the fantastic part, let\u2019s examine it a bit more.<\/p>\n\n
    The Change-Shortcut-Icon<\/code> function accepts a $iconNo<\/code> argument,\nwhich is the index into icons in resource file imageres.dll<\/code>, you can\nuse a separate *.ico<\/code> file for this, but the builtin icon resource is\njust easier for maintain, it\u2019s already there.<\/p>\n\n
    To view all icons in imageres.dll<\/code>, I recommand\nIconViewer<\/a>,\nafter install, it\u2019s integreted in windows property dialog. In above\nscript, I use number 26 and 28, those are:<\/p>\n