Built-in functions

Vow ships a builtin surface — call these without importing a package. Full tables live in the Built-in functions reference. App libraries (HTTP, etc.) come from vpm.

vow run tests/lang/phase1_stdlib.vow -- --grant clock:

Use case: string helpers

fn main(caps: Caps) -> int {
    assert str_to_upper("hi") == "HI";
    assert str_contains("hello", "ell") == true;
    assert str_starts_with("hello", "hel") == true;
    let n = match parse_int("42") {
        Ok(v) => v,
        Err(_e) => 0
    }
    print(str_join(["a", "b"], "-"))
    print(to_string_int(n))
    return n
}

Also: str_trim, str_replace, str_split, str_to_lower, str_ends_with, str_repeat, str_pad, str_find, str_slice, parse_float, to_string_*.

Use case: arrays and maps

// fragment-only
fn main(caps: Caps) -> int {
    var xs = [3, 1, 2]
    xs = array_push(xs, 4)
    xs = array_pop(xs)
    xs = array_sort(xs)
    assert xs[0] == 1;
    assert array_contains(xs, 2) == true;

    let evens = array_filter(xs, (x) -> x % 2 == 0)
    let doubled = array_map(evens, (x: int) -> x * 2)

    var m: Map<String, int> = map_new()
    m = map_set(m, "a", 1)
    assert map_contains_key(m, "a") == true;
    print map_keys(m)
    print doubled
    return len(xs)
}

v1 maps are Map<String, V> only.

Use case: math

fn main(caps: Caps) -> int {
    assert abs_int(-5) == 5;
    assert min_int(1, 9) == 1;
    assert max_int(1, 9) == 9;
    assert sqrt_f64(4.0) == 2.0;
    return 0
}

Also: abs_i64 / abs_f64, min_f64 / max_f64, pow_f64, floor_f64, ceil_f64, round_f64.

Use case: JSON round-trip

// fragment-only
fn main(caps: Caps) -> int {
    let parsed = json_parse("{\"n\":42}")
    return match parsed {
        Ok(v) => {
            print json_stringify(v);
            return 0;
        },
        Err(_) => 0 - 1
    }
}

JsonValue is opaque — json_parse / json_stringify / json_free. No Caps required.

Use case: debug print

fn main(caps: Caps) -> int {
    print("a=", 1, true)
    eprint("debug:", 2)
    return 0
}

Ambient — no Caps grant. Not part of the capability I/O model.

Use case: effectful I/O (needs a grant)

Builtin	Cap	Grant example
`read_file` / `file_mtime`	`FsRead`	`--grant fs-read:/tmp`
`write_file`	`FsWrite`	`--grant fs-write:/tmp`
`net_get` / `http_get`	`Net`	`--grant net:example.com`
`env_get`	`Env`	`--grant env:HOME`
`clock_now` / `clock_sleep`	`Clock`	`--grant clock:`
`rand_next`	`Rand`	`--grant rand:`
`thread_spawn` / `thread_join`	`Threads`	`--grant threads`
`process_spawn` / `process_wait`	`Proc`	`--grant proc:`
`db_connect`	`Db`	`--grant db:…` (stub)
`log_write`	`Log`	`--grant log:/tmp/app.log`

vow run app.vow -- --grant fs-read:/data --grant clock:

HTTP routing is not a builtin — use vow-web-server.

Built-in functions

Use case: string helpers

Use case: arrays and maps

Use case: math

Use case: JSON round-trip

Use case: debug print

Use case: effectful I/O (needs a grant)

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