YARMI_CONSTRUCT(
    (yarmi),        // client invoker namespace
    client_invoker, // name of the client invoker
    (proc(registration , on_registration, (string)                           )) // username
    (proc(activation   , on_activation  , (string, string, string)           )) // registration key : username : password
    (proc(login        , on_login       , (string, string)                   )) // username : password
    (proc(logout       , on_logout      , ()                                 )) // without args
    (proc(users_online , on_users_online, ()                                 )) // without args
    (proc(users_online , on_users_online, (string)                           )) // substring of username
    (enum(user_enum                     , (elem1, elem2, elem3)              )) // так можно декларить енум <<<<<<<<<<<<<<<<<<<<<
[1] (type(user_struct, (int, a)(long, b)(float, c)                           )) // а вот так юзер может описывать структуры. имея эту информацию, я могу сгенерить код сериализации/десериализации даже препроцессором.
[2] (proc(some_proc    , on_some_proc   , (user_struct)))
    ,
    (yarmi),        // server invoker namespace
    server_invoker, // name of the server invoker
    (proc(registration , on_registration, (string, std::string)              )) // message : registration key
    (proc(activation   , on_activation  , (string)                           )) // message
    (proc(login        , on_login       , (string)                           )) // message
    (proc(logout       , on_logout      , (string)                           )) // message
    (proc(users_online , on_users_online, (array<string>)                    )) // vector of usernames
);

server
{
    struct foo //...
    ping(foo x);
}
client
{
    struct bar // ...
    pong(bar x);
}

types
{
    struct foo //...
    struct bar // ...
}
service FirstService
{
    ping(foo x);
}
service SecondService
{
    pong(bar x);
}
// ...
// где-то ниже
connection SomeConn
{
    client provides SecondService;
    server provides FirstService;
}

YARMI_CONSTRUCT(
    client_invoker,                                                   // name of the client invoker class
    (proc(registration , on_registration, (string)                 )) // username
    (proc(activation   , on_activation  , (string, string, string) )) // registration key : username : password
    (proc(login        , on_login       , (string, string)         )) // username : password
    (proc(logout       , on_logout      , ()                       )) // without args
    (proc(users_online , on_users_online, ()                       )) // without args
    (proc(users_online , on_users_online, (string)                 )) // substring of username
    (enum(myenum1, (e0,=1)(e1)(e2)                                  ))
    (type(mytype1, (i8, a)(u8, b)(i32, c)(double, d)(string, e)     ))
    ,
    server_invoker,                                                   // name of the server invoker class
    (enum(myenum2, (e0)(e1,=2)(e2,=3)                              ))
    (type(mytype2, (i8, a)(u8, b)(i32, c)(double, d)(string, e)(array(i8), f)(map(i8, string), g)    )) <<<<<<<<<<<<<<<<<<<<<<<<<<<
    (proc(registration , on_registration, (string, string)         )) // message : registration key
    (proc(activation   , on_activation  , (string)                 )) // message
    (proc(login        , on_login       , (string)                 )) // message
    (proc(logout       , on_logout      , (string)                 )) // message
    (proc(users_online , on_users_online, (array<string>)          )) // vector of usernames
);

X>    (type(mytype2, (i8, a)(u8, b)(i32, c)(double, d)(string, e)(array(i8), f)(map(i8, string), g)    )) <<<<<<<<<<<<<<<<<<<<<<<<<<<
X>

{
    "Endpoint": {
        "type": "struct",
        "fields": [
            { "name": "IP", "type": "string" },
            { "name": "Port", "type": "uint" }
        ]
    },
    "Callback": {
        "type": "interface",
        "doc": "manages connection from server to client",
        "methods": [
            { "name": "addConnection", "args": [ { "name": "my_endpoint", "type": "Endpoint" } ], "async": true }
        ]
    }
}

// only CPP style comments allowed
proto(api) { // maybe one of 'api' or 'service'
    namespace yarmi;      // client invoker namespace
    class client_invoker; // name of the client invoker

    enum myenum1{}; e1,e2,e3=2}; // enum declaration
    struct mystruct1 { // struct declaration
        u32 a; // member of mystruct1
        string b;
        array<i64> c;
        set<string> d;
        map<u32, string> e; // some member of mystruct1
    };

    using ms = mystruct1; // using/typedef
    const u32 myu32 = 0;
    const myenum1 mye1 = myenum1::e1;

    [registration -> on_registration: (string)                 ] // username
    [activation   -> on_activation  : (string, string, string) ] // registration key : username : password
    [login        -> on_login       : (string, string)         ] // username : password
    [logout       -> on_logout      : ()                       ] // without args
    [users_online -> on_users_online: ()                       ] // without args
    [users_online -> on_users_online: (string)                 ] // substring of username
    ,
    namespace yarmi;      // server invoker namespace
    class server_invoker; // name of the server invoker

    [registration -> on_registration: (string, string)         ] // message : registration key
    [activation   -> on_activation  : (string)                 ] // message
    [login        -> on_login       : (string)                 ] // message
    [logout       -> on_logout      : (string)                 ] // message
    [users_online -> on_users_online: (array<string>)          ] // array of usernames
};