Standard Library: std.text and std.collections
● Intermediate5 min
Every type, method and function of std.text and std.collections: what the spec lists, then each declaration in its source, with its examples and the line that declares it.
Spec 14.9 · learn it in Text and Collections.
A declaration below shows what a program writes against: a type's fields, a function's parameters, what it gives, its contracts (require, ensure) and its examples. kavach test runs every example, so each one is true of the code.
What the spec lists
| Function | Gives |
|---|---|
text.pad_left(s, width, fill), text.pad_right(s, width, fill) | s filled with fill (a Char, default ' ') up to width characters |
text.words(s) | The words of s: the parts between runs of spaces, tabs and line breaks |
text.capitalize(s) | s with its first character in upper case |
text.truncate(s, max) | At most max characters of s |
text.is_blank(s) | Whether s has only spaces, tabs and line breaks |
text.find_ints(s) | Every whole number written inside s, in order: "a12b34" gives [12, 34] |
text.find_int(s) | The first of them, or none: "sd23" gives 23 |
text.find_float(s) | The first number with its fraction, or none: "pi is 3.14!" gives 3.14 |
text.nfc(s), text.nfd(s), text.nfkc(s), text.nfkd(s) | s in a Unicode normal form (UAX #15), so texts written with different code points compare equal: nfc joins a letter and its accent into one code point, nfd splits them, and the k forms also turn compatibility characters into plain ones (fi into fi, full-width １ into 1). The runtime gives these four (decision 0102); the rest of std.text is written in Kavach |
collections.chunks(items, size) | The items in lists of size (the last may be shorter) |
collections.zip(a, b) | Pairs of items at the same position, as long as the shorter list |
collections.unique(items) | Each item once, in the order first seen |
collections.counts(items) | How many times each item appears, in the order first seen |
collections.flatten(lists) | The items of all the lists, in order |
std.text · text.kav
use std.text: 0 types and 9 functions. stdlib/text/text.kav
pad_left function
s with fill added in front until it is width characters long.
pub fn pad_left(s: String, width: Int, fill: Char = ' ') -> String
require width >= 0
require width <= 1_000_000
ensure result.len() >= s.len()
example pad_left("7", 3, '0') == "007"
example pad_left("hello", 3) == "hello"pad_right function
s with fill added after it until it is width characters long.
pub fn pad_right(s: String, width: Int, fill: Char = ' ') -> String
require width >= 0
require width <= 1_000_000
ensure result.len() >= s.len()
example pad_right("ab", 4, '.') == "ab.."words function
The parts of s between runs of spaces, tabs and line breaks.
pub fn words(s: String) -> [String]
example words(" to be\tor\nnot ") == ["to", "be", "or", "not"]
example words("") == []capitalize function
s with its first character in upper case.
pub fn capitalize(s: String) -> String
ensure result.len() == s.len() or s.is_empty()
example capitalize("asha") == "Asha"
example capitalize("") == ""truncate function
At most max characters of s.
pub fn truncate(s: String, max: Int) -> String
require max >= 0
ensure result.len() <= max
example truncate("Kavach", 3) == "Kav"
example truncate("hi", 5) == "hi"is_blank function
Whether s has only spaces, tabs and line breaks.
pub fn is_blank(s: String) -> Bool
example is_blank(" \t\n")
example not is_blank(" a ")find_ints function
Every whole number written in s, in order ("a12b-3" gives [12, -3]). A comma or any other mark ends a number, and one too big for Int is left out. Unlike Int(s), which reads the whole text strictly (spec 2.1), this looks for numbers inside other text.
pub fn find_ints(s: String) -> [Int]
example find_ints("a12b34") == [12, 34]
example find_ints("pages 10-20") == [10, 20]
example find_ints("none here") == []find_int function
The first whole number written in s, as find_ints reads them, or none when there is none.
pub fn find_int(s: String) -> Int?
example find_int("12sdsfs") == 12
example find_int("sd23") == 23
example find_int("sd3f") == 3
example find_int("-5 °C") == -5
example find_int("item-3") == 3
example find_int("₹1,299") == 1
example find_int("no digits") == nonefind_float function
The first number written in s, with a fraction if it has one ("v2.5b" is 2.5, "x3" is 3.0), or none when there is none.
pub fn find_float(s: String) -> Float?
example find_float("pi is 3.14!") == 3.14
example find_float("x3") == 3.0
example find_float("-0.5 m") == -0.5
example find_float("end.") == nonestd.collections · collections.kav
use std.collections: 0 types and 5 functions. stdlib/collections/collections.kav
chunks function
The items in lists of size; the last list may be shorter.
pub fn chunks<T>(items: [T], size: Int) -> [[T]]
require size > 0
example chunks([1, 2, 3, 4, 5], 2) == [[1, 2], [3, 4], [5]]
example chunks([1], 3) == [[1]]zip function
Pairs of items at the same position, as long as the shorter list.
pub fn zip<A, B>(a: [A], b: [B]) -> [(A, B)]
example zip([1, 2, 3], ["a", "b"]) == [(1, "a"), (2, "b")]unique function
Each item once, in the order first seen.
pub fn unique<T>(items: [T]) -> [T]
example unique([3, 1, 3, 2, 1]) == [3, 1, 2]counts function
How many times each item appears, in the order first seen.
pub fn counts<T>(items: [T]) -> [T: Int]
example counts(["a", "b", "a"]) == ["a": 2, "b": 1]flatten function
The items of all the lists, in order.
pub fn flatten<T>(lists: [[T]]) -> [T]
example flatten([[1, 2], [], [3]]) == [1, 2, 3]