microsoft / microsoft/TypeScript

Introduce 'extends type' and 'extends modifier' or phantom types to simplify the language and speed it up.

Open
#29,438 1 comment 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

Awaiting More Feedback Suggestion
Dominant language
Go
Stars
111k
Forks
14.3k
Avg merge
2d 4h
Merged PRs (30d)
132

Description

Basically when using [k in keyof] and mutating structures in ways that can be found at these repositories it becomes apparent that to simplify the learning cure it would be better if the type modifiers such as optional/required/undefined/readonly|null can be accessed and interrogated separately from the type and modifiers mashed together..
So one can focus on writing a routine that would iterate the type to be integorate for the architectural structure/shape if to call it that, which allow one to write super fast simple methods to recursively no the difference between Record<string,any>, Array, never, unknown. instead of having to do the following: T extends Record<string,any> | undefined | readonly | null ? then recuse, else step over.

The following type integogation operators.

  1. extends ? mix of the type and modifiers
  2. extends type ? just the base type without any modifiers (can only be single type else undefined)
    so string | number = undefined, string = string, number = number, array = array, record = record, class = class, constructor = constructor, one needs to be able to differential record, which is interface from Date so require have a phantom type if the interface was generate from a class or something the features a constructor. Otherwise one will iterate into custom types like Date, which is a problem.
  3. extends modifiers ? Which just allows evaluation of modifiers. hopefully not a list in the backend implementation of the compiler code, hopefully just true and false flags for speed

Phantom types

Maybe just implement the concept of phantom symbols, that don't actually exists, were by optional/required, nullable, readonly, type can be access like :
T[PT.Required] extends true ? ..
T[PT.Nullable] extends true ? ...
T[PT.Readonly] extends true ? ...
T[PT.Type] extends true ? ...
T[PT.Cusom] extends true ? ... // For passing other information that doesn't exist to validate typings.
allow one to create the own phantom types, which information we will pass onto for downstream validation in some complex situations like Mongoose Update Statement validation which has 3 parts.

Work around Mongoose Update Statment

Work around Mongoose Types

https://github.com/Microsoft/TypeScript/issues/28699

Checklist

My suggestion meets these guidelines:

  • This wouldn't be a breaking change in existing TypeScript/JavaScript code
  • This wouldn't change the runtime behavior of existing JavaScript code
  • This could be implemented without emitting different JS based on the types of the expressions
  • This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
  • This feature would agree with the rest of TypeScript's Design Goals.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reading the proposed operators and phantom-type model in this issue, then compare the linked Mongoose examples and related issue #28699. Identify the TypeScript compiler entry points for conditional types and type modifiers before defining the intended behavior for unions, records, arrays, classes, and custom phantom metadata. Done requires a settled design and corresponding compiler tests.

Written by the indexing model from the issue text.

Assessment

Tech stack
typescript
Domain
compilers
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
15/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.