Funcfy 0.2.0

<p align="center"> <img
alt="funcfy - A lightweight, batteries-included functional programming toolkit for C#/.NET." src="https://github.com/leo-oliveira-eng/funcfy/blob/main/images/logo.png" height="400px" /> </p>

funcfy

A lightweight, batteries-included functional programming toolkit for C#/.NET.

Features

📋 Currying & partial application
🔄 Either, Maybe, Result types
📋 Functor, Applicative, Monad interfaces
📋 Lens utilities, compose, pipe

Getting Started

Install via NuGet:

dotnet add package Funcfy --version 0.1.0-alpha

Import the core namespace:

using Funcfy;

Example currying:

var add = Func.Curry((int x, int y) => x + y);
var add5 = add(5);
Console.WriteLine(add5(3));  // 8

Using Maybe<T>

The Maybe<T> type expresses optional values explicitly, avoiding null-reference surprises. Example:

  public class RepositoryAsync<Entity> : SpecificMethods<Entity>, IRepositoryAsync<Entity>
  {
  ...

  public async Task<Maybe<Entity>> FindAsync(int id)
      => await DbSet.FirstOrDefaultAsync(entity => entity.Id.Equals(id));
      
  ...
  }
      

The developer can act as follows when receiving the response:

  ...

      var entity = await EntityRepository.FindAsync(entityId);

      if (entity.IsEmpty)
          return response.WithError("Not found");

  ...

Creating Instances

• Empty (no value):

  var empty = Maybe<int>.Empty();          // IsFull == false, IsEmpty == true
  

• Full (with a value):

  var full = Maybe<string>.Full("hello");  // IsFull == true, Value == "hello"
  Maybe<int> also = 42;                      // implicit conversion wraps 42 as Full
  

Inspecting Values

Use IsFull or IsEmpty before accessing Value:

if (full.IsFull)
{
    Console.WriteLine(full.Value);
}
else
{
    Console.WriteLine("No value present.");
}

Conversion Operators

Thanks to the implicit operator, you can assign raw values directly:

Maybe<double> pi = 3.14;  // equivalent to Maybe<double>.Full(3.14)

⚠️ Important: Accessing Value when IsEmpty is true returns null for reference types or the default for value types. Always check IsFull first.

Contributing

1. Fork the repo
2. Create a feature branch (git checkout -b feature/foo)
3. Commit changes (git commit -m 'feat: add foo')
4. Push to your branch (git push origin feature/foo)
5. Open a Pull Request to develop branch