Language

#Strings and text

#Literals

Strings are written in double or single quotes; both mean the same:

var a = "Burn"
var b = 'it\'s "quoted"'
print(a, b, "x" == 'x')

A literal stays on one line; use \n for line breaks, or join lines with +.

Any other escape is an error ("unknown escape sequence").

#Templates

${...} inside a string evaluates any expression and inserts it as text:

var items = ["tea", "milk"]
var prices = {"tea": 2.5}
print("${len(items)} items: ${items}, tea costs ${prices["tea"] ?? 0.0}")
print("nested: ${"inner ${1 + 1}"}")

prints 2 items: ["tea", "milk"], tea costs 2.5 and nested: inner 2.

• Values are formatted the same way print formats them.
• A $ that is not followed by { is an ordinary character: "$5" is $5.
• Templates work in single-quoted strings too.

#Characters and length

A string is a sequence of Unicode characters (code points), stored as UTF-8. Everything that counts or indexes counts characters, not bytes:

var s = "a😀b"
print(len(s), s[1], substring(s, 1, 2), charCode(s[1]), bytes(s).length)

prints 3 😀 😀 128512 6.

• s[i] is the character at position i, as a one-character string. There is no separate character type.
• An index outside the string is a runtime error, like for arrays.
• for ch in s and for i, ch in s go over the characters.
• charCode(ch) gives a character's code point, fromCharCode(code) makes a one-character string, and bytes(s) / fromBytes(bytes) convert to and from UTF-8 as [uint8].

#Strings do not change

A string value never changes; every function returns a new string. s[0] = "x" is an error ("strings are immutable; build a new string instead").

var word = "burn"
var loud = upper(word)
var parts = split("a,b,c", ",")
print(word, loud, parts, replace("1-2-3", "-", "+"))

Building a string piece by piece with += is still fast: when a variable is the only owner of its string, Burn appends in place instead of copying, so a loop of s += piece takes time in proportion to the final length.

#Comparing

== compares the characters. <, >, <= and >= compare character by character by code point, so all uppercase ASCII letters come before lowercase ones ("Z" < "a"), and a string comes before any longer string that starts with it ("ab" < "abc"). For a case-insensitive comparison, compare lower(a) with lower(b).

#Converting

Floats print with a .0 when they are whole (1.0), with the shortest digits that read back as the same number (33.333333333333336), and in exponent form when very large or small (1e100, 1e-7).

#More

The built-in string functions (trim, split, replace, indexOf, startsWith, ...) are listed in built-in functions; std/strings adds padding, line and word splitting, and character tests.