microsoft / microsoft/TypeScript

Eliminate non-generic functions

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Description

Every non-generic function can be expressed as generic function with a single type parameter corresponding to each argument. Explicit parameter type annotations simply correspond to extends constraints on the type parameters of the generic equivalent.

While the title of the issue is "eliminate non-generic functions", in practice this simply gets rid of all the syntax ceremony involved in declaring generic functions. A function declaration as follows:

function repeat(item, n: number) => Array(n).fill(item)

will be inferred as: type F = <T1 extends any, T2 extends number>(item: T1, number: T2) => T1[], and the result of invoking it with repeat("foo", 10) is inferred as string[], not any[].

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

No files, tests, or entry points are named. Start by studying the proposed inference examples in the issue and the surrounding TypeScript type-inference design; done would require an agreed implementation that infers generic parameters and constraints from ordinary function declarations without explicit generic syntax.

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
Mostly clear
Newbie friendliness
25/100

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