String

A String value represents a sequence of characters.

Creating strings

A string can be created by wrapping the characters in double quotes:

let myStringVar = "Hello, world!";

Strings are immutable, this means that whenever you want to modify a string you'll get a new one and the original one will remain unchanged.

String length

You can use the size operator # to retrive the size of a String:

let myString = "12345";

io.print(#myString); // 5

io.print(#"") // 0

Strings concatenation

A String can be created by concatenating two other String values by using the concatenation operator ..:

let stringA = "Hello, ";

let stringB = "world!";

let stringC = stringA .. stringB;

io.print(stringC); // Hello, world!

io.print(stringA .. stringA .. stringC); // Hello, Hello, Hello, world!

Accessing individual characters

The indexing operator can be used to read individual characters in a String:

let stringA = "Hello";

io.print(stringA[0]); // H

io.print(stringA[1]); // e

io.print(stringA[2]); // l

io.print(stringA[3]); // l

note

Given that strings are immutable, you can't change a character by using indexed assignment.

Accessing with ranges

You can use slicing to extract a portion of a string, much as you would with an Array value:

let stringA = "Hello";

io.print(stringA[0:3] .. "!"); // Hell!

io.print(stringA[:-1] .. "!"); // Hell!

io.print(stringA[-2:]); // lo

String manipulation

Most string manipulation functions can be found in the string core module.

VM Internals

Internalization

Strings are internalized. This means that up to a certain length, if the value is the same, the same exact string in memory will be used for each content. This makes comparing small strings very fast:

let myShortString = "short";

// This is fast!

if (myShortString == "short") {

}

In the example above the VM will simply compare the memory location of the two strings, a simple integer comparison, knowing that the string "short" is internalized. If the strings are the same their location in memory must match.

Wide-string support

Currently wide strings are not supported. This means that while you can output multi-byte encoded character (such as emojis), Melon will see the multi-byte components as distinct characters. While this may not be a big issue in some cases, it's something to be aware of when doing string manipulation as it may break the string (eg: a multi-byte sequence is interrupted).

This is also why if you use the size operator # on a multi-byte char it will not return 1.