RejectedSoftware Forums

Why does the following code give:

source/app.d(45,12): Error: cannot implicitly convert expression __lambda1 of type void delegate(HTTPServerRequest req, HTTPServerResponse res) @system to void delegate(HTTPServerRequest req, HTTPServerResponse res) @safe
source/app.d(45,12): Error: cannot implicitly convert expression __lambda1 of type void delegate(HTTPServerRequest req, HTTPServerResponse res) @system to void delegate(HTTPServerRequest req, HTTPServerResponse res) @safe
source/app.d(55,26): Error: template instance app.staticI18NTemplate!"index.dt" error instantiating

import vibe.d;

struct TranslationContext
{
    import std.typetuple : TypeTuple;
    alias languages = TypeTuple!("en_US", "de_DE");
    mixin translationModule!"example";
    static string determineLanguage(HTTPServerRequest req)
    {
        import std.string : split, replace;
        auto acc_lang = "Accept-Language" in req.headers;
        if (acc_lang)
            return replace(split(*acc_lang, ",")[0], "-", "_");
        return null;
    }
}

void renderI18NTemplate(string file)(HTTPServerRequest req,
                                     HTTPServerResponse res)
{
    switch (TranslationContext.determineLanguage(req)) {
    default:
        static string diet_translate__(string key, string context=null) {
            return tr!(TranslationContext, TranslationContext.languages[0])
                (key);
        }
        render!(file, req, diet_translate__)(res);
        break;
        foreach (lang; TranslationContext.languages) {
        case lang:
            mixin("struct " ~ lang ~ " {
			static string diet_translate__(string key, string
			context=null) {
			return tr!(TranslationContext, lang)(key); }
			}
			alias translate = " ~ lang ~ " .diet_translate__;");
            render!(file, req, translate)(res);
            break;
        }
    }
}

HTTPServerRequestDelegate staticI18NTemplate(string file)()
{
    return (HTTPServerRequest req, HTTPServerResponse res) {
        renderI18NTemplate!(file)(req, res);
    };
}

shared static this()
{
    auto settings = new HTTPServerSettings;
    settings.port = 8080;
    settings.bindAddresses = ["::1", "127.0.0.1"];
    listenHTTP(settings, staticI18NTemplate!"index.dt");
    logInfo("Please open http://127.0.0.1:8080/ in your browser.");
}