darwen 1.3.0

A relational algebra library for Rust
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38

//! Demonstrates how to subtract one relation from another with the `DIFFERENCE` operation.

use darwen::prelude::{Relation, RelationBuilder, ScalarType};
use darwen::{heading, tuple};

fn all_numbers() -> Relation {
    RelationBuilder::new()
        .with_heading(heading!(number = ScalarType::Integer).unwrap())
        .with_body(vec![
            tuple!(number = 4).unwrap(),
            tuple!(number = 8).unwrap(),
            tuple!(number = 15).unwrap(),
            tuple!(number = 16).unwrap(),
            tuple!(number = 23).unwrap(),
            tuple!(number = 42).unwrap(),
        ])
        .build()
        .unwrap()
}

fn already_typed() -> Relation {
    RelationBuilder::new()
        .with_heading(heading!(number = ScalarType::Integer).unwrap())
        .with_body(vec![
            tuple!(number = 4).unwrap(),
            tuple!(number = 8).unwrap(),
            tuple!(number = 15).unwrap(),
        ])
        .build()
        .unwrap()
}

fn main() {
    let all_numbers = all_numbers();
    let already_typed = already_typed();

    println!("{}", all_numbers.difference(&already_typed).unwrap());
}