Rain
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Documentation

How Rain actually works: syntax, modules, stdlib. Written against the rainc tree, not aspirational features.

Get started

  • Install RainDownload a pre-built binary for macOS or Linux, or build from source if you have repo access.
  • Hello WorldYour first Rain program: save a file and run it.
  • Build from sourceCompile Rain locally when you have the rainc repository.

Basics

  • VariablesDeclare mutable bindings with `var`.
  • Types & literalsDynamic typing: numbers, strings, booleans, arrays, maps, and `nil`.
  • StringsLiterals, interpolation, escaping, and concatenation.
  • OperatorsArithmetic, comparison, logic, and assignment.
  • PrintShow output with `print`.
  • CommentsLine comments with `//`.
  • ArraysLiteral arrays, indexing, and methods.
  • MatrixDefine dense numeric matrices with the math module.
  • MapsString-keyed hash maps with `{ }` literals and bracket access.

Control flow

  • If / elseBranch on conditions: parentheses required.
  • While loopsRepeat while a condition is true.
  • For loopsC-style `for (init; condition; increment)`, `for (item von array)`, and `for (key, value von map)`.
  • Break / continueExit a loop early or skip to the next iteration.
  • Versuch / fang (try/catch)Catch runtime errors with `versuch { } fang (err) { }`: the Rain equivalent of try/catch.

Functions

Classes

  • ClassesObjects with methods, fields, and constructors.
  • InheritanceExtend classes with `<` and call superclass methods with `super`.
  • Optional chainingSafely read nested instance fields when a link in the chain might be `nil`.

Modules

  • ModulesLoad built-ins and your own `.rn` files with `benutzen`. Every top-level binding is exported: no export keyword.
  • mathScalars, array math, matrices, activations, and neural-network helpers.
  • csvRead CSV files into arrays or matrices: built for MNIST-scale training pipelines.
  • strString search, slice, split, join, format, and parsing.
  • jsonParse and stringify JSON.
  • httpHTTP server, routing, middleware, client, and CORS.
  • dbSQLite: open, exec, query with parameters.
  • ioRead, write, append files; read stdin.
  • osPlatform info, environment, sleep, exit.
  • timeCurrent date, time parts, formatting.

Reference