Skip to content

Library reference

Everything built into Fubby. There's nothing to import, and every entry comes from the same table that's checked against the interpreter.

Find a function

Output and size

Signature	What it does
`print(values...)`	Print the values to standard output, separated by spaces.
`len(value) -> Int`	Number of items in a list or map, or characters in a string.

Strings

Signature	What it does
`str_upper(String text) -> String`	Convert text to upper case.
`str_lower(String text) -> String`	Convert text to lower case.
`str_trim(String text) -> String`	Remove whitespace from both ends.
`str_contains(String text, String part) -> Bool`	Whether text contains part.
`str_replace(String text, String from, String to) -> String`	Replace every occurrence of from with to.
`str_split(String text, String separator) -> List`	Split text into a list of strings.
`str_length(String text) -> Int`	Number of characters.
`str_starts_with(String text, String prefix) -> Bool`	Whether text starts with prefix.
`str_ends_with(String text, String suffix) -> Bool`	Whether text ends with suffix.
`str_index_of(String text, String part) -> Int`	Character index of the first match, or -1.
`str_substring(String text, Int start, Int end) -> String`	Characters from start up to, but not including, end.
`str_repeat(String text, Int count) -> String`	Repeat text count times. The result is limited to 1 MiB.

Math

Signature	What it does
`math_abs(number) -> Float`	Absolute value.
`math_floor(number) -> Float`	Round down.
`math_ceil(number) -> Float`	Round up.
`math_sqrt(number) -> Float`	Square root. The number cannot be negative.
`math_pow(base, exponent) -> Float`	base raised to exponent.
`math_min(a, b) -> Float`	The smaller of two numbers.
`math_max(a, b) -> Float`	The larger of two numbers.
`math_sin(radians) -> Float`	Sine.
`math_cos(radians) -> Float`	Cosine.
`math_tan(radians) -> Float`	Tangent.
`math_log(number) -> Float`	Natural logarithm. The number must be above zero.
`math_exp(number) -> Float`	e raised to number.
`math_round(number) -> Float`	Round to the nearest whole number.
`math_trunc(number) -> Float`	Drop the fractional part.

List and map functions

Signature	What it does
`list_contains(List list, item) -> Bool`	Whether the list contains item.
`list_index_of(List list, item) -> Int`	Index of the first match, or -1.
`list_reverse(List list) -> List`	A new reversed list.
`list_slice(List list, Int start, Int end) -> List`	A new list from start up to, but not including, end.
`list_concat(List first, List second) -> List`	A new list joining both lists.
`list_insert(List list, Int index, value) -> List`	A new list with value inserted. The original list is unchanged.
`list_remove(List list, Int index) -> List`	A new list without the element at index. The original list is unchanged.
`map_keys(Map map) -> List`	The keys, sorted.
`map_values(Map map) -> List`	The values, in sorted key order.

JSON, encoding and matching

Signature	What it does
`json_encode(value) -> String`	Convert a value to JSON text.
`json_decode(String json) -> value`	Parse JSON text into maps, lists, and values.
`encoding_hex_encode(String text) -> String`	Encode text as hexadecimal.
`encoding_hex_decode(String hex) -> String`	Decode even-length hexadecimal to text.
`encoding_base64_encode(String text) -> String`	Encode text as Base64.
`encoding_base64_decode(String base64) -> String`	Decode Base64 to UTF-8 text.
`regex_is_match(String text, String pattern) -> Bool`	Whether text matches the regular expression. Look-around and backreferences are not supported.

Date, time and random numbers

Signature	What it does
`time_parse_utc(String timestamp) -> Int`	Parse an RFC 3339 timestamp to Unix seconds.
`time_format_utc(Int seconds) -> String`	Format Unix seconds as YYYY-MM-DDTHH:MM:SSZ.
`time_is_leap_year(Int year) -> Bool`	Whether year is a leap year.
`time_days_in_month(Int year, Int month) -> Int`	Days in a month, where month is 1 to 12.
`clock_unix() -> Int`	Current time in Unix seconds.
`clock_unix_millis() -> Int`	Current time in Unix milliseconds.
`random_int(Int min, Int max) -> Int`	Random integer in an inclusive range. Not cryptographically secure.

System, environment and errors

Signature	What it does
`env_get(String name) -> String`	Value of an environment variable, or an empty string if it is not set.
`env_has(String name) -> Bool`	Whether an environment variable is set.
`system_os() -> String`	Operating system name.
`system_arch() -> String`	CPU architecture name.
`system_cwd() -> String`	Current working directory.
`system_args() -> List`	Process arguments.
`error_message(String error) -> String`	The text of a caught error.
`error_contains(String error, String part) -> Bool`	Whether a caught error contains part.

Files

Signature	What it does
`file_read(String path) -> String`	Read a text file. Respects FUBBY_FS_ROOT.
`file_write(String path, String contents)`	Write a text file, replacing it if it exists. Respects FUBBY_FS_ROOT.
`file_exists(String path) -> Bool`	Whether a path exists. Respects FUBBY_FS_ROOT.

Collection and database methods

Signature	What it does
`list.push(value)`	Add a value to the end of the list.
`list.pop() -> value`	Remove and return the last value.
`collection.length() -> Int`	Number of items.
`map.set(String key, value)`	Set a key. You can also write map["key"] = value.
`map.get(String key) -> value`	Value for a key. A missing key is an error.
`map.has(String key) -> Bool`	Whether the key exists.
`map.remove(String key) -> value`	Remove a key and return its value. A missing key is an error.
`db.execute(String sql, List params) -> Map`	Run a statement with ?1-style parameters. Returns changes and last_insert_rowid.
`db.query(String sql, List params) -> List`	Run a query with ?1-style parameters. Returns a list of row maps.

Moon: HTTP and SQLite

Signature	What it does
`moon.http`	HTTP client. Network access is denied unless FUBBY_NET_ALLOWLIST allows the host.
`moon.db`	Database access.
`moon.security`	Network policy and limit information.
`moon.net`	Reserved for later. Calling it is an error.
`moon.http.get(String url, Map options) -> Map`	Send a GET request and return status, headers, body, and url. Options can be empty: headers, timeout_ms, max_bytes.
`moon.http.post(String url, String body, Map options) -> Map`	Send a POST request and return status, headers, body, and url. Options can be empty: headers, timeout_ms, max_bytes.
`moon.db.sqlite`	SQLite databases.
`moon.db.sqlite.open(String path, Map options) -> Database`	Open a database file, or ":memory:". Options can be empty: timeout_ms, max_rows, max_bytes.
`moon.security.network_allowed(String host) -> Bool`	Whether the current allowlist permits this host.
`moon.security.limits() -> Map`	The enforced HTTP and SQLite limits.

Snow: web server

Signature	What it does
`snow.get(String path, String handler)`	Register a GET route during startup. The handler name is a function with no parameters and no return value.
`snow.post(String path, String handler)`	Register a POST route during startup.
`snow.put(String path, String handler)`	Register a PUT route during startup.
`snow.patch(String path, String handler)`	Register a PATCH route during startup.
`snow.delete(String path, String handler)`	Register a DELETE route during startup.
`snow.route(String method, String path, String handler)`	Register a route for a named HTTP method during startup.
`snow.static(String prefix, String directory)`	Serve a directory under a URL prefix, registered during startup.
`snow.before(String handler)`	Run a handler before each request, registered during startup.
`snow.after(String handler)`	Run a handler after each request, registered during startup.
`snow.on_error(String handler)`	Set the handler for failed requests, registered during startup.
`snow.request() -> Map`	The current request: method, path, body, params, query, headers, and state.
`snow.error() -> String`	The current error message, inside an error handler.
`snow.responded() -> Bool`	Whether a response has already been produced.
`snow.header(String name, String value)`	Set a response header.
`snow.status(Int status)`	Set the response status, from 200 to 599.
`snow.text(String body, Int status = 200)`	Send a plain text response.
`snow.html(String body, Int status = 200)`	Send an HTML response.
`snow.json(value, Int status = 200)`	Send a JSON response.
`snow.template(String source, Map values) -> String`	Fill {{name}} placeholders with HTML-escaped values.

Bela: background tasks

Signature	What it does
`bela.spawn(String function, input) -> Int`	Start a task and return its id. The function takes no parameters and returns nothing; the input is passed as JSON. Workers cannot spawn tasks.
`bela.input() -> value`	The task's input. Only available inside a task.
`bela.result(value)`	Set the task's result. Only available inside a task.
`bela.join(Int task) -> value`	Wait for a task and return its result. Each task can be joined once.
`bela.cancel(Int task) -> Bool`	Request cooperative cancellation. Returns false if the task has already finished.
`bela.status(Int task) -> String`	queued, running, cancelling, completed, failed, cancelled, timed_out, or joined.
`bela.channel(Int capacity) -> Int`	Create a bounded channel with capacity 1 to 64, and return its id.
`bela.send(Int channel, value)`	Send a value, waiting while the channel is full.
`bela.recv(Int channel) -> value`	Receive a value, waiting while the channel is empty.
`bela.close(Int channel)`	Close a channel.
`bela.sleep(Int milliseconds)`	Pause for 0 to 30000 milliseconds.