rl_lang/docs/entries/tutorial/t1/
p12.rs

1use crate::docs::entry::{ConceptCategory, ConceptEntry, DescriptionEntry, DescriptionKind};
2pub static STEP_NULL: ConceptEntry = ConceptEntry {
3    name: "12. null",
4    summary: "null",
5    category: ConceptCategory::Types,
6    prerequisites: &[],
7    descriptions: &[
8        DescriptionEntry {
9            kind: DescriptionKind::Explanation,
10            title: None,
11            description: "null means the absence of a value. a variable can hold null regardless of its declared type. functions that do not explicitly return anything return null implicitly",
12            examples: &[
13                "dec int x = null\nprintln(x) // null\n\nfn do_nothing() {\n    // returns null implicitly\n}",
14            ],
15            expected_output: &[],
16        },
17        DescriptionEntry {
18            kind: DescriptionKind::Explanation,
19            title: None,
20            description: "use is_null from std::types to check if a value is null before using it. this avoids surprises when a function might return nothing",
21            examples: &[
22                "get is_null from std::types\n\nfn find_even(arr[int] nums) -> int {\n    for n in nums {\n        if (n > 10) { return n }\n    }\n    return null // nothing matched\n}\n\ndec int res = find_even([1, 2, 3])\n\nif (is_null(res)) {\n    println(\"nothing found\")\n} else {\n    println(res)\n}",
23            ],
24            expected_output: &[],
25        },
26        DescriptionEntry {
27            kind: DescriptionKind::Explanation,
28            title: None,
29            description: "exercise: write a function find_first_correct that takes the guesses array and the secret number and returns the index of the first correct guess, or null if the player never guessed correctly\n\nhint: use a for loop with a counter variable alongside it",
30            examples: &[
31                "get is_null from std::types\n\nfn find_first_correct(arr[int] guesses, int secret) -> int {\n    dec int i = 0\n    for g in guesses {\n        if (g == secret) { return i }\n        i += 1\n    }\n    return null\n}\n\ndec int idx = find_first_correct(guesses, secret)\n\nif (is_null(idx)) {\n    println(\"you never guessed correctly\")\n} else {\n    println(format(\"you got it on guess number {}\", idx + 1))\n}",
32            ],
33            expected_output: &[],
34        },
35    ],
36    pitfalls: &[],
37    related: &[],
38    related_stdlib: &[],
39    since: None,
40};
rl_lang/docs/entries/tutorial/t1/p12.rs

rl_lang/docs/entries/tutorial/t1/
p12.rs
