std/string

std/string provides functions for working with String values.

API

pub ext fun len(s: String) Int;
pub ext fun at(s: String, i: Int) Char;
pub ext fun slice(s: String, start: Int, len: Int) String;
pub ext fun eq(a: String, b: String) Bool;

pub fun stringLen(s: String) Int;
pub fun fromChar(c: Char) String;
pub fun pushChar(s: String, c: Char) String;

Function	Description
len(s)	Returns the number of characters in s
at(s, i)	Returns the character at index i (zero-based)
slice(s, start, len)	Returns a substring starting at start with length len
eq(a, b)	Returns true if a and b are equal
fromChar(c)	Converts a Char to a single-character String
pushChar(s, c)	Appends character c to string s, returns new string

Examples

Basic string operations

import "std/string";
import "std/io" { println, printInt };

fun main() Int {
    var name: String = "Zap";

    printInt(string.len(name));                    // 3
    println(string.fromChar(string.at(name, 0)));  // "Z"
    println(string.slice(name, 1, 2));             // "ap"

    var same: Bool = string.eq("hello", "hello");  // true
    var diff: Bool = string.eq("hello", "world");  // false

    return 0;
}

Building strings character by character

import "std/string";
import "std/io" { println };

fun reverse(s: String) String {
    var result: String = "";
    var i: Int = string.len(s) - 1;
    while i >= 0 {
        result = string.pushChar(result, string.at(s, i));
        i = i - 1;
    }
    return result;
}

fun main() Int {
    println(reverse("hello"));  // "olleh"
    println(reverse("Zap"));    // "paZ"
    return 0;
}