Hagamos un Algoritmo de Inferencia Genérica

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¿Cómo funciona la inferencia genérica en TypeScript? Para la mayoría de las personas, esto puede parecer una caja negra. El líder de desarrollo de TypeScript, Ryan Cavanaugh, nos guía desde un simple algoritmo de inferencia genérica de un solo paso hasta un modelo simplificado de cómo realmente funciona la inferencia genérica en TypeScript, con un enfoque en ejemplos motivadores.

Ryan Cavanaugh
Ryan Cavanaugh
25 min
21 Sep, 2023

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Video Summary and Transcription

Hola, bienvenidos a Hagamos un Algoritmo de Inferencia. Hoy, les daré una visión general de alto nivel de cómo funciona el proceso de inferencia genérica de TypeScript. Exploraremos diferentes posibilidades como 'any', 'unknown' o 'number'. El algoritmo para inferir argumentos de tipo recopila candidatos y elige el primero, asegurando la mejor respuesta correcta. El concepto del mejor supertipo común se utiliza para determinar el mejor candidato. La sensibilidad al contexto se aborda en el algoritmo, permitiendo un comportamiento óptimo.

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1. Introducción a la inferencia genérica de TypeScript

Short description:

Hola, bienvenidos a Vamos a Crear un Algoritmo de Inferencia. Soy Ryan Kavanaugh, el líder de desarrollo para el equipo del compilador de TypeScript en Microsoft. Hoy, les daré una visión general de alto nivel de cómo funciona el proceso de inferencia genérica de TypeScript. Discutiremos ejemplos, posibles opciones y compensaciones. Comencemos con un ejemplo: F, una función con un parámetro de tipo, un parámetro regular y un tipo de retorno. TypeScript infiere el argumento de tipo basado en el valor proporcionado. Exploraremos diferentes posibilidades como 'any', 'unknown' o 'number'.

Hola, bienvenidos a Vamos a Crear un Algoritmo de Inferencia. Soy Ryan Kavanaugh. Soy el líder de desarrollo para el equipo del compilador de TypeScript en Microsoft. Mis objetivos hoy son mostrarles una visión general de alto nivel de cómo funciona el proceso de inferencia genérica de TypeScript.

La gente a menudo me pregunta cómo funciona esto y no puedo darles una explicación completa en 20 minutos, pero podemos repasar muchos de los conceptos de alto nivel y explicar cuáles son los objetivos generales. Esta va a ser una charla basada en ejemplos porque nuestro lenguaje está impulsado por ejemplos motivadores que realmente muestran por qué las cosas funcionan de la manera en que lo hacen, y vamos a discutir otras posibles opciones de cómo podrían funcionar las cosas y discutir algunas de las compensaciones que se toman al tomar diferentes decisiones en el camino.

Así que comencemos con un ejemplo. Tengo F aquí. Tiene un parámetro de tipo, T, tiene un parámetro regular, x, de tipo T, y devuelve un T. Cuando TypeScript ve una llamada a una función genérica, actúa como si hubieras escrito un argumento de tipo aquí. Puedes escribir argumentos de tipo tú mismo, pero no tienes que hacerlo. Y si no lo haces, intentaremos averiguar qué quieres que vaya aquí. En este caso, vamos a pasar el valor 42 para x, y la pregunta que necesitamos responder es, como, rellenar el espacio en blanco. ¿Qué va allí? Si hubiéramos obligado al usuario a escribir un argumento de tipo en esa posición, ¿qué habrían escrito? Podemos empezar a hacer algunas suposiciones sobre lo que podríamos querer hacer.

Una cosa que podrías decir es, es cualquier cosa. Si no nos dices, simplemente vamos a asumir cualquier cosa, y luego dejar que las fichas caigan donde puedan, ¿verdad? Eso no sería muy bueno. Creo que a la gente no le gustaría eso. Podríamos decir desconocido. En este ejemplo, desconocido es una apuesta segura, ¿verdad? 42 es un desconocido válido. Lo que sea que f devuelva seguramente será un desconocido. Así que desconocido es una inferencia correcta, y podrías hacer eso, y podrías hacer un argumento teórico para desconocido. Podríamos decir, bueno, 42 es un primitivo. Los primitivos son número y cadena y booleano. Así que tal vez quisiste decir toda la familia de primitivos cuando invocaste f aquí, y tal vez eso es lo que quieres que suceda. O podríamos decir, no, número. 42 es un número. Probablemente eso es lo que quieres para t. También podríamos hablar sobre el tipo literal 42. Voy a fingir que los tipos literales no existen para el propósito de esta charla, porque complica mucho las cosas. Así que un número es lo más bajo que va ahora.

2. Algoritmo para Especificar la Inferencia Genérica

Short description:

Creemos que el número es la respuesta correcta aquí. Parece que si llamaste a f de t y le diste un número, el valor más específico que podemos elegir es el correcto. Entonces, ¿cuál es el algoritmo que escribiríamos si tuviéramos que especificar cómo funciona eso?

Creemos que el número es la respuesta correcta aquí. Parece que si llamaste a f de t y le diste un número, el valor más específico que podemos elegir es el correcto. Entonces, ¿cuál es el algoritmo que escribiríamos si tuviéramos que especificar cómo funciona eso? Bueno, diríamos que vamos a buscar t y encontrar un lugar donde ocurra en la lista de argumentos, en la lista de parámetros en este caso. Vamos a decir, oh, 42 fue pasado a x, así que encontramos a este tipo, encontramos a este, nos alineamos, decimos, sí, ese es el t. Diremos que 42 es un número, por lo tanto t es un tipo número, por lo tanto es como si hubieras escrito f de número, por lo tanto x es un número. Genial. La charla ha terminado. Todos pueden irse a casa.

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