Generics and Maybe Monad

• Una monada es un concepto de la programación funcional que proporciona un contexto para trabajar con valores encapsulados. Proporciona una forma de aplicar funciones a estos valores encapsulados mientras maneja el contexto de manera transparente, como el manejo de errores, el estado mutable, la entrada/salida, etc.

• A monoid is a design pattern that represents an associative binary operation with an identity element. In functional programming, a monoid is often used to combine values in a way that is both commutative and associative, such as adding numbers or concatenating strings. It uses to do a reduce operation over a list of elements.

• A functor is a design pattern that represents a container or structure that can be mapped over. In functional programming, a functor is often used to apply a function to each element of a collection and return a new collection with the transformed elements.

Generics Over the struct

type Maybe[T any] struct {
    value T
    err   error
}

or several types

type Maybe[T int32|float32|string] struct {
    value T
    err   error
    }

Generics Over a method

func Just[T any](val T) Maybe[T] {
    return Maybe[T]{value: val}
}

Generics Over a func method of a struct

func (m Maybe[T]) OnSuccess(f func(T) Maybe[T]) Maybe[T] {
    if m.err != nil {
        return m
    }
    return f(m.value)
}