Null coalesce

Despite the fact that Jacy does not have null replacing it with Option such as what Rust does, this particle is called so to use common term "null-coalesce" familiar to SQL, JS, etc. programmers.

Null coalescing operator

This operator exists in, for example JavaScript - ??, also known as Elvis operator - ?: in many languages (PHP, Kotlin) or COALESCE in SQL.

At first I would like to remind that Jacy does not have ternary operator a ? b : c that was the source of Elvis operator syntax with removed second term a ?: b = a ? a : b. Thus Jacy will use ?? operator further in this particle and likely in the implementation.

Null coalescing operator is a kind of disjunction (||, or or in Jacy) but for values which are "optional" (nullable). That's why I came up with an idea of null-conjunction, that is && operator for optional values.

Nullack operator

Nullack is new term I'll use here as short form of (lack of null values), nullack operator is a null-conjunction operator. This idea is pretty uncommon thus behavior I choose would not likely be useful, anyway I want to discuss it.

Operator syntax is not specified, thus [OP] will be used further.

Code sample:

a [OP] b

Where a has type Option<T> and Option<b> has type U.

This operator MUST return None in case when a OR b are None values.

What this operator should return if both of a AND b are Some values is described in variants below.

Variant #1

Return (a!, b!): (T, U), that is a tuple where first and second elements are unwrapped a and b respectively.