Built-in methods

Methods are called with a dot and they chain. Every signature below was checked against the implementation rather than transcribed.

String

Method	Result	Notes
`upper()` / `lower()`	String	`"auth".upper()` → `"AUTH"`
`len()`	Int	counts characters: `"héllo".len()` → `5`
`trim()`	String	strips surrounding whitespace
`split(sep)`	List	`"a,b".split(",")` → `["a", "b"]`
`replace(from, to)`	String	every occurrence
`starts_with(prefix)` / `ends_with(suffix)`	Bool
`contains(substr)`	Bool	`"hello".contains("ell")` → `true`
`to_int()` / `to_float()`	Int / Float	a malformed number is an error, not `null`
`slice(start, end)`	String	substring by character index, `end` exclusive, indices clamped
`to_str()`	String	identity, for use in chains
`parse_json()` / `parse_yaml()` / `parse_toml()`	Object	integers become `Int`; a failure is `E0314`
↳ fidelity		key order is the document’s; YAML `<<` is merged; a TOML datetime becomes a `String`
`parse_duration()`	Int (seconds)	`"1h30m"` → `5400`; units `d/h/m/s`; `E0319`
`parse_datetime()`	Int (epoch UTC)	RFC 3339 or `YYYY-MM-DD`; offsets `±HH:MM`; `E0320`
`sha256()`	String	lower-case hex digest
`base64()` / `base64_decode()`	String	standard alphabet with padding; invalid input is `E0321`

Int

Method	Result	Notes
`abs()`	Int
`to_float()`	Float	widening; there is no `Float.to_int()`, which would have to round
`to_str()`	String
`format_duration()`	String	`5400` → `"1h30m"`; `0` → `"0s"`
`format_datetime()`	String	RFC 3339 UTC: `946684800` → `"2000-01-01T00:00:00Z"`

Float

Method	Result
`abs()`	Float
`round(digits)`	Float
`to_str()`	String

Bool

Method	Result
`to_str()`	String

List

Method	Result	Notes
`len()`	Int
`first()` / `last()`	element	an empty list is `E0317`
`get(i)` / `get(i, default)`	element	a miss gives `null`, or the default if you supply one
`contains(item)`	Bool	structural equality
`compact()`	List	drops `null`
`uniq()`	List	deduplicates, keeping first occurrences in order
`map (x, i) -> ... end`	List	the callback receives the element and its index
`filter (x, i) -> Bool end`	List	a non-Bool from the callback is `E0306`
`join(sep)`	String	scalars only; containers are `E0307`
`sort()`	List
`reverse()`	List
`sum()`	Int
`min()` / `max()`	element
`flatten()`	List	one level: `[[1], [2, 3]]` → `[1, 2, 3]`
`to_object()`	Object	builds an object from `{ key, value }` pairs; a repeated key is `E0323`
`reduce(init) (acc, e) -> … end`	Any	left fold; the initial value is required
`any (e, i) -> Bool end`	Bool	some element matches; `false` for an empty list
`all (e, i) -> Bool end`	Bool	every element matches; `true` for an empty list
`find(default) (e, i) -> Bool end`	Any	first match, or the default
`index_of(value, default)`	Int	index of the first equal element, or the default; the default must be an `Int`
`group_by (e, i) -> key end`	Object	elements by a String key, keys in the order they first appear (D39)
`sort_by (e, i) -> key end`	List	ascending and stable; keys follow `sort()` (D39)
`flat_map (e, i) -> [...] end`	List	`map`, then the lists joined one level; a non-List from the lambda is `E0306` (D39)
`zip(other)`	List	`{ left, right }` pairs; lists of different lengths are `E0327` (D39)
`slice(start, end)`	List	`end` exclusive: `[1, 2, 3].slice(1, 3)` → `[2, 3]`
`to_json()` / `to_yaml()` / `to_toml()`	String	the compact form, for embedding; `to_toml` on a list is `E0603`
`to_json_pretty()` / `to_yaml_pretty()` / `to_toml_pretty()`	String	the form a person reads, for a file that gets diffed

Object

Method	Result	Notes
`len()`	Int
`keys()` / `values()`	List	declaration order
`contains(key)`	Bool
`get(key, default)`	value	a miss gives the default
`entries()`	List	`{ key, value }` objects in declaration order; the inverse of `to_object()`
`merge(other)`	Object	the right side’s keys win
`to_json()` / `to_yaml()` / `to_toml()`	String	the compact form, for embedding
`to_json_pretty()` / `to_yaml_pretty()` / `to_toml_pretty()`	String	the form a person reads, for a file that gets diffed

Operators that build values

Most operators are numeric. Two are not, and they are the only ones whose result can be larger than what went in.

Expression	Result	Notes
`"a" + "b"`	String	joins two strings; interpolation `"#{a}#{b}"` does the same
`[1] + [2, 3]`	List	joins two lists; the operands are unchanged

+ never converts. "port " + 8080 is E0306, and the diagnostic names the side to call .to_str() on. Joining is bounded at 1,000,000 list elements and 16 MiB of string, reported as E0322.

Global functions

Function	Right required	Behaviour
`range(n)`	—	`[0, 1, … n-1]`
`env(name, default)`	`--allow-env`	an environment variable; absent → the default
`read_file(path)`	`--allow-read`	the file’s contents as a string; a relative path is read from the manifest’s folder (D37)
`fail(message)`	—	stops with `E0531` and your message

A method call takes precedence over an object field of the same name that happens to hold a function. A package’s exported functions are called with the same syntax: pkg.fn(...).

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The Aura Language