> For the complete documentation index, see [llms.txt](https://osl.mistium.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://osl.mistium.com/tools-and-reference/builtins-and-methods.md). # Built-ins and value methods This page covers language-level APIs that do not require an import. Standard-library APIs live under [Packages](/standard-library/packages.md). ## Core functions | Function | Purpose | | ----------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------- | | `typeof(value)` | Returns the runtime type name. When the value has a single known type, the comparison folds at compile time and warns as a constant condition. | | `len(value)` | Returns the length of a supported value. | | `string(value)` | Converts a value to text. Prefer `.toStr()` in application code. | | `number(value)` | Converts a value to a decimal number. Prefer `.toNum()`. | | `int(value)` | Converts a value to an integer. Prefer `.toInt()`. | | `boolean(value)` | Converts a value using OSL truthiness. Prefer `.toBool()`. | | `array(value)` | Converts a supported value to an array. | | `object(value)` | Converts a supported value to an object. | | `min(...values)` | Returns the smallest numeric value. | | `max(...values)` | Returns the largest numeric value. | | `clamp(value, low, high)` | Restricts a number to a range. | | `round(value)`, `floor(value)`, `ceil(value)`, `abs(value)` | Basic numeric operations. | | `sqrt(value)`, `pow(base, exponent)` | Roots and powers. | | `sin(value)`, `cos(value)`, `tan(value)` | Trigonometric functions. | | `random(low, high)` | Returns a random number in the requested range. | | `range(start, end)` | Creates an inclusive range. The `to` operator is usually clearer. | | `keys(object)`, `values(object)`, `entries(object)` | Reads object contents. | | `btoa(value)`, `atob(value)` | Base64 encode and decode. | | `symbol(name)` | Creates a symbol value. | | `sleep(seconds)` | Blocks for a duration in seconds. | ## Methods on every value | Method | Result | | ----------------------------- | -------------------------------------------------- | | `.toStr()` | String conversion | | `.toNum()` | Number conversion | | `.toInt()` | Integer conversion | | `.toBool()` | Boolean conversion | | `.getType()` | Runtime type name | | `.assert(type)` | Runtime type assertion | | `.assertElse(type, fallback)` | Assertion with a fallback | | `.assertElse(fallback)` | Assertion with the type inferred from the fallback | | `.len` or `.len()` | Length where supported | | `.contains(value)` | Membership where supported | Assertion shorthand uses `value.` for `.assert(type)` and `value.(fallback)` for `.assertElse(type, fallback)`. Keep the fallback's opening parenthesis adjacent to `>`. A space separates a following block, as in `for value in items. (`. ## Strings Common string methods include: ``` append prepend insert delete contains containsAny startsWith endsWith index lastIndex count match replace replaceFirst split left right trim trimText strip stripStart stripEnd toUpper toLower toTitle toMixed padStart padEnd reverse toArr ord btoa atob encodeHex decodeHex encodeBin decodeBin hashMD5 hashSHA1 hashSHA256 hashSHA512 ``` String positions are 1-based. Indexing and iteration use Unicode code points. `.len` counts UTF-8 bytes, so it may be larger than the number of characters. There is no `repeat` method. Use multiplication, as in `"a" * 3`. ## Arrays Common array methods include: ``` append prepend insert delete pop shift fill swap contains index first last left right trim concat map filter some every sort sortBy reverse randomOf join clone getKeys getValues min max sum product resize ``` Array positions are 1-based. Mutating methods change the original array. `.clone()` creates an independent deep copy. ## Objects Common object methods include `getKeys`, `getValues`, `getEntries`, `contains`, `insert`, `delete`, `pick`, `clone`, `toStr`, `jsonParse`, and `getProto`. Cloning a null value returns null. Objects return `null` for missing fields. Assignment shares the object; `.clone()` makes a deep copy and preserves a typed dictionary's key and value types. ```osl string[object] roles = {user: {position: 1}} string[object] copied = roles.clone() copied["user"].position = 2 log roles["user"].position // 1 ``` Object shorthand resolves variable names even when they match a command name. For example, `string error = "failed"` followed by `{error}` creates `{error: "failed"}`. ## Numbers and booleans Numbers provide methods such as `round`, `floor`, `ceiling`, `abs`, `sqrt`, `clamp`, `sin`, `cos`, `tan`, `asin`, `acos`, `atan`, `log`, `ln`, `sign`, `isPrime`, and `chr`. Booleans support the universal conversion, type, assertion, and prototype methods. ## Prototypes Strings, arrays, objects, numbers, and functions can resolve methods through prototypes. Prefer ordinary functions or named types for application structure. Prototype changes are global to the value type and are harder to trace in a large project. ## Nullish fallback `??` uses its fallback only when the left value is null. Fallbacks can be chained, including when several consecutive values are null: `primary ?? backup ?? 42` returns `42` when both variables are null. Null guards also narrow nullable typed arrays, typed dictionaries, and named records. After `if values == null return`, a `string[]?` value can use string-array methods without an assertion. Package handles report their qualified `typeof` name, such as `*cache.Cache` or `*process.Process`. Built-in `xml`, `map`, `set`, `canvas`, `option`, and `result` values keep their language type names.