rl_lang/docs/entries/tutorial/t2/
p_b8.rs

1use crate::docs::entry::{ConceptCategory, ConceptEntry, DescriptionEntry, DescriptionKind};
2
3pub static ADV_PROGRAM_LOOP: ConceptEntry = ConceptEntry {
4    name: "8. the program loop",
5    summary: "the program loop",
6    category: ConceptCategory::Tooling,
7    prerequisites: &[],
8    descriptions: &[
9        DescriptionEntry {
10            kind: DescriptionKind::Explanation,
11            title: None,
12            description: "part 1 gave you a complete CSV library. now build the task manager on top of it. the program is a REPL - read, evaluate, print, loop. it reads a command, acts on it, prints the result, and loops until the user quits",
13            examples: &[
14                "// main.rl skeleton\nget csv\nget read, println from std::io\nget trim           from std::str\n\nCONST string TASKS_FILE = \"tasks.csv\"\n\nfn main() {\n    dec arr[arr[string]] tasks = csv_load(TASKS_FILE)\n    println(\"task manager ready. type 'help' for commands\")\n\n    while (true) {\n        dec string input   = read(\"> \")\n        dec string command = trim(input)\n\n        if (command == \"quit\") { break }\n\n        // dispatch commands here\n        println(concat(\"unknown command: \", command))\n    }\n\n    println(\"goodbye\")\n}",
15            ],
16            expected_output: &[],
17        },
18        DescriptionEntry {
19            kind: DescriptionKind::Explanation,
20            title: None,
21            description: "commands like 'add buy milk' have two parts: the command name and the arguments. split on the first space to separate them. use index_of to find where the first space is, then slice to extract each part",
22            examples: &[
23                "get index_of, slice, trim from std::str\n\nfn parse_command(string input) -> arr[string] {\n    dec int space = index_of(input, \" \")\n    if (space == -1) {\n        return [trim(input), \"\"] // no args\n    }\n    dec string cmd  = slice(input, 0, space)\n    dec string args = trim(slice(input, space + 1, len(input)))\n    return [cmd, args]\n}",
24            ],
25            expected_output: &[],
26        },
27        DescriptionEntry {
28            kind: DescriptionKind::Explanation,
29            title: None,
30            description: "exercise: get the REPL loop running. it should read input, parse the command, and for now just echo back what command and args it parsed. quit should exit cleanly\n\nexpected output:\n  > add buy milk\n  command: add  args: buy milk\n  > list\n  command: list  args:\n  > quit\n  goodbye",
31            examples: &[
32                "fn main() {\n    println(\"task manager ready. type 'help' for commands\")\n\n    while (true) {\n        dec string       input  = read(\"> \")\n        dec arr[string]  parts  = parse_command(trim(input))\n        dec string       cmd    = parts[0]\n        dec string       args   = parts[1]\n\n        if (cmd == \"quit\") { break }\n\n        println(format(\"command: {}  args: {}\", cmd, args))\n    }\n\n    println(\"goodbye\")\n}",
33            ],
34            expected_output: &[],
35        },
36    ],
37    pitfalls: &[],
38    related: &[],
39    related_stdlib: &[],
40    since: None,
41};
rl_lang/docs/entries/tutorial/t2/p_b8.rs

rl_lang/docs/entries/tutorial/t2/
p_b8.rs
