concepts.md

Maybe Syntax

Generally, there're two kinds of maybe syntax: maybe block and maybe variable.

Maybe Block

maybe ("algorithm") {
    // do path 0
} or {
    // do path 1
} or {
    // do path 2
}

It defers choice for different code paths to runtime.

Maybe Variable

    int i = maybe("a") {1, 2, 3};

The variable i is maybe variable.

Why not int i = maybe("a") 1, 2, 3;

If you have nested maybe variable:

    int i = maybe("a") 1, maybe("b") 2, 3, 4;

I don't know it should be:

    int i = maybe("a") {1, maybe("b") {2, 3, 4}};

or

    int i = maybe("a") {1, maybe("b") {2, 3}, 4};

or

    int i = maybe("a") {1, maybe("b") {2} 3, 4};

The complier doesn't know that as well, so it panics.

Maybe Label

The string in maybe ("label") is maybe label.

The maybe label can not contains "." or "$"! Because we use mongodb to store data. And mongodb doesn't allow "." or "$" as key.