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Documentation

Learn Langoost

Everything about the language as it takes shape — from a first Hello, world to structured concurrency. Start with the tour, then dive into the topics below.

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What is Langoost?

Langoost is a statically-typed scripting language that compiles to bytecode and runs on a fast stack-based VM. Built for backend scripting — like PHP, but with no per-request cold start.

Install & run

How to build Langoost from source with Go and run your first .goost script, start the REPL, or launch the persistent execution server.

Language

Language tour

A fast tour of Langoost syntax — variables, types, functions, control flow, arrays, objects, template strings, classes, and error handling, with runnable examples.

Types & values

Langoost's value types — int, float, bool, string, array, object, void/nil, any, and the json/yaml/xml data types — plus number literals, template strings, and conversion.

Functions

Functions in Langoost — declarations, optional type annotations, anonymous functions and closures, variadic parameters, the spread operator, recursion, and hoisting.

Value methods

Built-in methods you can call directly on Langoost values — string methods, array methods, and numeric methods on int, float, and bool.

Classes & types

Object-oriented Langoost — class declarations, methods, single inheritance with extends and super, named type declarations, and object construction.

Control flow

Conditionals and loops in Langoost — if / else if / else, while, for..in over arrays and ranges, and the break and continue loop-control keywords.

Arrays

Working with arrays in Langoost — literals, indexing, negative indices, the append built-in, and the full set of array methods like map, filter, reduce, push, and sort.

Error handling

Handling errors in Langoost with try, catch, throw, and defer, plus the runtime.error and runtime.panic helpers.

Modules & imports

Importing standard-library and local modules in Langoost — namespace imports, named imports, sub-module access, and module resolution order.

Backend

HTTP server

Build an HTTP API in Langoost with http.serve and a handler function that receives method, path, query, and body, and returns a string response.

Concurrency

Concurrency in Langoost with the thread module — spawning goroutines, async futures, channels, mutexes, and sharing state across isolated VMs.

Web libraries

Pure-Langoost libraries for serving HTTP with Request/Response types, WebSockets, and Server-Sent Events.

Standard library

Standard library overview

Index of the Langoost standard library — text, data, encoding, math, collections, time, filesystem, OS, networking, crypto, data stores, and concurrency modules.

strings

String utilities — search, slice, split, join, replace, trim, case, padding, classification, formatting, and a string builder.

regex

Regular expressions in Langoost — match, find, findAll, replace, split, capture groups, and pattern validation.

types

Runtime type checks and conversions for int, float, bool, char, string, and null/void.

json

Parse, query, edit, merge, and pretty-print JSON, plus streaming parse of arrays and NDJSON.

yaml

Parse and serialize YAML, and convert between YAML and JSON.

xml

Validate, pretty-print, query, and convert XML to JSON or an object tree.

url

Parse and build URLs and query strings, with percent-encoding helpers.

encode

Encoding helpers — base64, hex, CSV, binary integers/floats, and JSON/XML, organized into submodules.

serialize

Binary serialization with msgpack and a simplified protobuf, to and from JSON strings.

compress

Compress and decompress data with gzip, zlib, lz4, and brotli. All I/O is base64.

math

Math utilities — basic arithmetic, trig, logarithms, random, constants, bitwise ops, clamping, and interpolation.

collections

Data structures — stack, queue, set, ordered map, heap, trie, ring buffer, list, tuple, and array helpers.

time

Time and dates — clock, date components, timers/sleep, durations, and formatting, organized into submodules.

date

Convenience date API over Unix timestamps — now, parse, format, component extraction, and arithmetic.

timer

Async timers — setTimeout, setInterval, and clear, with callback functions.

io

Filesystem access — read/write/append files, directories, streaming for large files, and path helpers.

os

Operating-system access — environment, process info, signals, permissions, syscall info, and args.

exec

Run shell commands and programs, read exit codes, and access env and the working directory.

signal

Register POSIX signal handlers (SIGINT, SIGTERM, etc.) with callback functions.

terminal

Terminal/TUI control — raw mode, key reading, size, and ANSI colors, cursor, and screen sequences.

runtime

Runtime introspection and a process-global shared key-value store, plus reflect, error, panic, and env helpers.

memory

Byte buffers, string interning pools, and allocator/GC introspection.

logging

Leveled logging — debug, info, warn, error, fatal — with a global debug toggle.

net

Networking — TCP, UDP, TLS, DNS, and an HTTP client, using integer connection handles.

http

HTTP client — get, post, put, patch, delete, head, status, and a generic request with custom headers.

crypto

Cryptography — hashing, HMAC, AES, RSA, Ed25519, secure random, certificates, and TLS info.

redis

Redis client — connect and run key/value, list, hash, and pub/sub commands over integer handles.

sql

SQL databases — open SQLite, Postgres, or MySQL and run exec, query, queryOne, queryValue, and transactions.

mongo

MongoDB client for Langoost — connect and run insertOne, insertMany, find, findOne, updateOne, deleteOne, and count over an integer handle.

Reference

CLI reference

The langoost command-line interface — run scripts, start the REPL, launch the persistent HTTP server, disassemble bytecode, and print the version.

Architecture

How Langoost works under the hood — the lexer/parser/compiler/VM pipeline, the 4-byte bytecode format, the stack model, the module cache, and per-request VM isolation.