​

void main() @nogc {

    import std.experimental.all;

    auto xs = only(1, 2, 3);

    int a = 2, b = 3;

    xs.pack(a, b).map!(unpack!((x, a, b) => x * a * b));

}

​

auto pack(T, Captures...)(T arg, Captures captures) {

    string mix(int n) {

        import std.conv: to;

        string s = "zip(arg,";        

        foreach (i; 0 .. n) {

            s ~= "repeat(captures[" ~ i.to!string ~ "]),";

        }

        s ~= ")";

        return s;

    }

    import std.range: repeat, zip;

    return mixin(mix(Captures.length));

}

​

template unpack(alias func) {

    import std.typecons: isTuple;

    auto unpack(TupleType)(TupleType tup) if (isTuple!TupleType) {

        return func(tup.expand);

    }

}