josdejong/mathjs

Easier types when working with "create"

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#2,322 opened on Sep 21, 2021

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Description

I followed the custom bundling docs and created my own instance of math.js, like this:

const math = create({ addDependencies, bignumberDependencies, divideDependencies, meanDependencies }, config);
const mbn = this.math.bignumber!;

What I don't like is that I have to use the ! non-null assertion operator, even if it is clear that the bignumber property should be non-null (as per the bignumberDependencies object passed to create).

I further had to disable the @typescript-eslint/no-non-null-assertion ESLint rule, because the lint task was failing.

My feature request: let the compiler know that the objects returned by create are non-null, based on the inputs provided.

Contributor guide

Research direction
Explore the use of conditional types or mapped types in TypeScript to infer the return type of the `create` function based on the dependencies object, ensuring that properties are non null when corresponding dependencies are provided.
Tech stack
typescript
Domain
developer experience
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
TypeScript
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60