Mangrove

Mangrove is a Ruby toolkit that brings a functional, statically-typed flavor to your Sorbet-enabled projects. Inspired by concepts from languages like Rust and Haskell, Mangrove provides a robust set of tools—primarily Result and ADT-like Enums—to help you write safer, more expressive Ruby code.

• Documentation
• Coverage

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Highlights

• Sorbet Integration Built from the ground up to work smoothly with Sorbet's type system.

• Result Type Model success/failure outcomes with explicit types—no more "return false or nil" for errors!

• Enums (ADTs) Define your own sealed enums with typed variants. Each variant can hold distinct inner data.

• Functional Patterns Chain transformations or short-circuit error handling with a clean monadic style.

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Installation

bundle add mangrove

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Usage Overview

Mangrove revolves around Result and a sealed "Enum" mechanism for ADTs.

Result

A Result is either Ok(T) or Err(E). You can compose them with monadic methods like and_then and or_else. For "early returns" in a functional style, you have two main approaches:

1. A context-based DSL (e.g., ctx.try!)
2. An instance method on Result itself, unwrap_in(ctx), which behaves similarly.

Here's an example of chaining requests and short-circuiting on error:

class MyClient
  extend T::Sig

  sig { returns(Mangrove::Result[String, StandardError]) }
  def connect
    # ...
    Mangrove::Result::Ok.new("Connected")
  end

  sig { params(data: String).returns(Mangrove::Result[String, StandardError]) }
  def request(data)
    # ...
    Mangrove::Result::Ok.new("Response: #{data}")
  end
end

# Let's say we have a special DSL context for collecting short-circuits:
# (Hypothetical usage)

Result.collecting(String, StandardError) do |ctx|
  final_result = MyClient.new
    .connect
    .and_then do |connection|
      MyClient.new.request("Payload from #{connection}")
    end

  # Option 1: Call from the context
  response_data = ctx.try!(final_result)
  # => If 'final_result' is Err, short-circuits now;
  #    otherwise returns the Ok(T) value.

  puts response_data  # If no errors, prints "Response: Connected"

  # Option 2: Call via 'unwrap_in(ctx)'
  # This does the same short-circuit if 'Err', using the context:
  response_data_alt = final_result.unwrap_in(ctx)
end

# More chaining, etc...

Extension Methods

Mangrove provides convenient extension methods through Mangrove::Result::Ext. These methods allow you to easily wrap any value in a Result:

# Include the extension in your classes
class Object
  include Mangrove::Result::Ext
end

# Now you can use in_ok and in_err on any object
"success".in_ok  # => Result::Ok("success")
"error".in_err   # => Result::Err("error")

# Useful in method chains
"hello"
  .upcase
  .in_ok
  .map_ok { |s| "#{s}!" }  # => Result::Ok("HELLO!")

# Error case
"error message"
  .in_err
  .map_err { |e| "#{e}!" } # => Result::Err("error message!")

Enums (ADTs)

Define an enum with typed variants:

class MyEnum
  extend Mangrove::Enum

  variants do
    variant IntVariant, Integer
    variant StrVariant, String
    variant ShapeVariant, { name: String, age: Integer }
  end
end

int_v = MyEnum::IntVariant.new(123)
puts int_v.inner  # => 123

For more details on monadic methods, short-circuit contexts, and advanced usage, please visit the official documentation or see real-world usages in spec/.

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Commands for Development

git config core.hooksPath hooks
bundle install
bundle exec tapioca init
bundle exec tapioca gems -w `nproc`
bundle exec tapioca dsl -w `nproc`
bundle exec tapioca check-shims
bundle exec rspec -f d
bundle exec rubocop -DESP
bundle exec srb typecheck
bundle exec spoom srb tc
bundle exec ordinare --check
bundle exec ruboclean --verify
bundle exec yardoc -o docs/ --plugin yard-sorbet
bundle exec yard server --reload --plugin yard-sorbet
rake build
rake release

Run these commands to maintain code quality, generate documentation, and verify type safety under Sorbet.

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Contributing

We welcome contributions! To get started:

1. Fork & clone the repo
2. Install dependencies: bundle install
3. Make your changes and add tests
4. Submit a PR

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License

Mangrove is available under the MIT License. See the LICENSE file for details.